Native Trees, Urban Forest Management Planning, and

Residents: Knowledge, Attitudes, and Actions

by

Andrew David Almas

A thesis submitted in conformity with the requirements

for the degree of Doctor of Philosophy

Department of Geography and Planning

University of Toronto

© Copyright by Andrew David Almas 2017

ii

Native Trees, Urban Forest Management Planning, and

Residents: Knowledge, Attitudes, and Actions

Andrew David Almas

Doctor of Philosophy

Department of Geography and Planning

University of Toronto

2017

Abstract

In the past decade, municipalities across North America have increased investment in their urban

forests in an effort to maintain and enhance the numerous benefits provided by them. Some

municipalities have drafted long-term urban forest management plans (UFMPs) that emphasize

the planting of native trees to improve ecological integrity, and participation of residents, since

the majority of urban trees are typically located on residential property. Yet it is unclear if

municipal foresters are mindful of UFMP goals or what residents’ level of knowledge, attitudes,

and actions are regarding native trees and urban forestry goals. Through a case study of southern

Ontario municipalities, I administered interviews with municipal foresters and a survey exploring

residents’ ability to identify the native status of common tree species, as well as their attitudes

and actions regarding urban forest issues. The results indicate that all municipalities with

management plans emphasize native species, and many justify their planting as a way to increase

ecological integrity. However, only a fraction of species native to the region are available

through nursery stock, meaning many are not planted by municipalities. The results of the

survey indicate that residents are better able to identify common native trees than non-native

trees, although knowledge-levels are low, and there are failures of resident outreach within the

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case study municipalities. Although residents generally have positive attitudes towards native

trees, few are interested in planting native species if they create a hazard or increase costs. These

positive attitudes do not translate into emphasizing native species when actually selecting tree

species to plant. This dissertation adds to existing research surrounding native species

management in urban ecosystems, and understandings about how urban forestry policy

influences residents and municipal actors. Future research is needed to determine species

suitability for urban plantings and meaningful ways of engaging with new residents.

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Acknowledgments

I am offering a heartfelt thank you to the myriad of people who have inspired my curiosity,

overseen my development, proven me wrong/right/somewhere in between, critically engaged

with this material, and shown patience for it’s completion. My PhD Supervisor, Tenley Conway

deserves recognition for the sound judgment, advice, and support that brought this dissertation to

fruition. My PhD Committee Members, Virginia Maclaren and Sandy Smith deserve recognition

for their compelling critiques and thought-provoking ideas about this study. My family, who

have been incredibly supportive of my studies, and Meredith and Matthew who have inspired

this whole thing. I would also like to acknowledge my colleagues in the House Lab that helped

with data collection and discussed formative ideas of this project, as well as the municipal

foresters and survey participants who took time out of their busy schedules to interact with me

about my dissertation. Finally, I would like to thank the University of Toronto and Department

of Geography and Planning, among others for funding my research, conference attendance, and

other academic endeavours. If it “takes a village to raise a child”, it takes a nation to develop a

PhD student!

Chapter Acknowledgments

This dissertation has been written as a compilation of the following co-authored manuscripts that

have been or will be submitted for publication in peer-reviewed journals. Chapter 2 and 3 have

already been published and are included in this dissertation with permission from Elsevier and

Springer Nature, respectively. All chapters were designed and written by the principal author and

Ph.D. candidate. The co-author (Dr. Tenley Conway) was involved in conceptual discussions,

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assistance with statistical analysis and survey design, interview format design, and participation

in review and editing of the written materials.

1) Almas, A. and Conway, T.M., 2016. The role of native species in municipal urban forest

planning and practice: A case study of Carolinian Canada. Urban Forestry and Urban

Greening 17 (1), 54-62. (Chapter 2)

2) Almas, A. and Conway, T.M., In press. Residential knowledge of native tree species: A case

study of residents in four southern Ontario municipalities. Environmental Management doi:

10.1007/s00267-016-0772-5. (Chapter 3)

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Table of Contents

Acknowledgments.......................................................................................................................... iv

Table of Contents ........................................................................................................................... vi

List of Tables ................................................................................................................................. ix

List of Figures ................................................................................................................................ xi

List of Appendices ........................................................................................................................ xii

Chapter 1 Introduction .....................................................................................................................1

1.1 Background Information ......................................................................................................1

1.1.1 Dissertation Context.................................................................................................1

1.2 Research Objectives and Dissertation Overview .................................................................2

1.3 The Urban Forest .................................................................................................................3

1.3.1 Benefits of the Urban Forest ....................................................................................5

1.4 Urban Forest Theory and Concepts .....................................................................................7

1.4.1 Native Species in the Urban Forest ..........................................................................7

1.4.2 Ecosystem Services and Ecological Integrity ..........................................................9

1.4.3 Assisted Migration .................................................................................................11

1.5 Urban Forest Stakeholders .................................................................................................13

1.5.1 Municipalities and UFMPs ....................................................................................13

1.5.2 Residents and the Urban Forest .............................................................................16

1.6 Study Area – Carolinian Canada........................................................................................18

Chapter 2 The Role of Native Species in Municipal Urban Forest Planting and Practice: A

Case Study of Carolinian Canada .............................................................................................20

2.1 Introduction ........................................................................................................................20

2.2 Ecological Integrity, Assisted Migration, and Non-native Trees in the Urban Forest ......22

2.3 Methods..............................................................................................................................27

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2.3.1 Study Area .............................................................................................................27

2.3.2 Urban Forest Management Plan and Planting List Review ...................................29

2.3.3 Interviews ...............................................................................................................29

2.4 Results ................................................................................................................................32

2.4.1 Urban Forest Management Plans and Planting Lists .............................................32

2.4.2 Planting Practice ....................................................................................................34

2.4.3 Ecological Integrity and Assisted Migration in Practice .......................................41

2.5 Discussion and Conclusion ................................................................................................42

Chapter 3 Residential Knowledge of Native Tree Species: A Case Study of Residents in Four

Southern Ontario Municipalities ...............................................................................................47

3.1 Introduction ........................................................................................................................47

3.2 Residents and the Urban Forest .........................................................................................49

3.3 Methods..............................................................................................................................53

3.3.1 Study Area .............................................................................................................53

3.3.2 Resident Surveys ....................................................................................................55

3.4 Results ................................................................................................................................58

3.4.1 Knowledge .............................................................................................................61

3.4.2 Factors related to knowledge-level ........................................................................64

3.5 Discussion ..........................................................................................................................66

Chapter 4 Resident Attitudes and Actions Towards Native Tree Species: A Case Study of

Residents in Four Southern Ontario Municipalities ..................................................................72

4.1 Introduction ........................................................................................................................72

4.2 Native Species and Residential Actors in the Urban Forest ..............................................74

4.3 Methods..............................................................................................................................78

4.3.1 Study Area .............................................................................................................78

4.3.2 Resident Surveys ....................................................................................................79

4.3.3 Analysis..................................................................................................................79

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4.4 Results ................................................................................................................................81

4.4.1 Native Species Attitudes ........................................................................................83

4.4.2 Native Species Actions ..........................................................................................88

4.5 Discussion and Implications ..............................................................................................91

Chapter 5 Summary and Recommendations ..................................................................................96

5.1 Dissertation Summary ........................................................................................................96

5.1.1 UFMPs, Municipalities, and the Attitudes and Actions of Municipal Foresters

Regarding Native Tree Species ..............................................................................96

5.1.2 Residents’ Level of Knowledge of Native Tree Species and Urban Forest

Issues ......................................................................................................................98

5.1.3 Resident Attitudes and Actions Regarding Native Tree Species and Urban

Forest Issues ...........................................................................................................99

5.2 Recommendations for Management and Future Research ..............................................101

5.2.1 Management Recommendations ..........................................................................101

5.2.2 Future Research Recommendations .....................................................................104

References ....................................................................................................................................107

Appendices ...................................................................................................................................122

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List of Tables

Table 1 Carolinian Zone municipalities with an Urban Forest Management Plan……………..28

Table 2 Carolinian Zone municipalities included in the study that were contacted for an

interview but have not enacted an Urban Forest Management Plan as of March 2015………….28

Table 3 Terms that were defined for the interviewees for ideological consistency…………….31

Table 4 Most commonly planted tree species in Carolinian Canada…………………………...35

Table 5 Reasons given as to why the use of native species should be increased in municipal

plantings………………………………………………………………………………………….39

Table 6 Municipal demographics……………………………………………………………….55

Table 7 Terms that were defined for the survey respondents for ideological consistency……..56

Table 8 Summary of socio-demographic and tree planting variables, shown as percentage

of all respondents…………………………………………………………………………...……60

Table 9 Comparison between survey participant demographics and municipal

demographics…………………………………………………………………………………….61

Table 10 Number and percentage of all survey participants in each category of knowledge of the

native-status of common tree species……………………………………………………………62

Table 11 Percentage of respondents who correctly identified tree species……………………..62

Table 12 Percentage of correct responses for native and non-native tree species, as well as other

urban forest topics………………………………………………………………………………..63

Table 13 Cross tabulation results based on Cramer’s V, with p-value in parentheses…………64

x

Table 14 Summary of socio-demographic and tree planting variables, shown as percentage of

all respondents………………………………………………………………………………...…82

Table 15 Principle components analysis of native tree species attitude questions……………..86

Table 16 Analysis of variance (ANOVA) with PCA components, socio-demographics, and

action variables…………………………………………………………………………………..87

Table 17 Summary of respondents’ tree planting actions………………………………………90

Table 18 Cross tabulation results of action and socio-demographic variables…………………90

Table 19 Variables retained in the logistic regression………………………………………….91

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List of Figures

Figure 1 – Map of the Carolinian forest zone in Canada showing the municipalities in the

study……………………………………………………………………………………..……….19

Figure 2 – Most common factors considered by municipal foresters when choosing tree species

to plant………………………………………………………………………………………...…36

Figure 3 – Reasons why non-native tree species are selected in favor of native

species………………………………………………………………………………………...….40

Figure 4 - Map of the Carolinian forest zone in Canada showing the four surveyed

municipalities...………………………………………………………………………………..…54

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List of Appendices

Appendix A – Written survey distributed to residents

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Chapter 1

Introduction

1.1 Background Information

1.1.1 Dissertation Context

As global urbanization has increased over the past decades, and people’s interactions with nature

have become more contingent upon the greenery in urban areas, geographers, urban foresters and

others have increasingly acknowledged the benefits obtained from urban forests, as well as

conceived of better ways to manage the goods and services we garner from them. Nowhere is

this more relevant in Canada than in southern Ontario, where more than 90% of the population

lives in urban areas (Statistics Canada, 2011). Municipal urban forest management plans

(UFMPs) have been introduced in the past decade to guide the future structure of the urban tree

canopy, increase ecosystem services, and work towards conservation of native ecology (City of

Burlington, 2010; City of Guelph, 2012; City of London, 2014; City of Mississauga, 2014; City

of St. Catharines, 2011; City of Toronto, 2013; Town of Ajax, 2011; Town of Oakville, 2008).

However, several knowledge gaps exist in terms of the efficacy of these long-term plans given

their recent, widespread adoption; the relationship between the plans’ goals and practice by

municipal foresters; and the knowledge, attitudes, and actions of urban residents, who are

counted on to be willing partners in managing the tree canopies in their municipality.

2

1.2 Research Objectives and Dissertation Overview

The goal of this dissertation is to addresses knowledge gaps that exist in understanding the

knowledge, attitudes, and actions of urban forestry practitioners and residents regarding native

tree species and related management practices that shape urban forests. Three subsequent

chapters outlining distinct but related studies of native species and urban forest management

address this overall goal through a series of specific objectives.

Chapter 2 addresses the gaps in our understanding of the formulation and implementation of

UFMPs and on-going discussions about ecological integrity, non-native species benefits and

assisted migration. The objectives of the Chapter 2 study are to (1) examine the role of native

species in UFMPs; (2) explore municipal foresters’ attitudes and actions related to native tree

species, and (3) explore if municipalities with and without formal management plans are making

different decisions regarding native tree species planting. These objectives are addressed

through a case study of municipalities in Carolinian Canada (Ontario, Canada), by examining

UFMPs and municipal tree planting lists, and interviewing urban foresters from 16

municipalities with and without UFMPs.

Chapter 3 assesses residents’ knowledge about native species and the urban forest to provide a

better understanding of knowledge and decisions related to urban trees. The objectives of the

Chapter 3 study are to (1) explore residents’ ability to determine if common tree species are

native or exotic to the study area, (2) assess residents’ familiarity with municipal urban forest

management plans, and (3) examine the factors related to different levels of residents’ native

species knowledge. These goals are addressed through a survey of residents in four urban

municipalities in Carolinian Canada (Ontario, Canada).

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Chapter 4 examines broader implications of the relationships present between residents and

native species in urban forests to address gaps in our understanding of urban residents’

relationship with native tree species. The main objectives of the Chapter 4 study are to (1)

explore urban residents’ attitudes and actions related to native tree species; (2) examine if the

presence of a municipal UFMP emphasizing native species is related to those attitudes or actions;

(3) determine if attitudes vary among residents with different sociodemographic characteristics;

and (4) explore if positive attitudes towards native species translates into planting native tree

species. These objectives are addressed through the same survey as utilized in Chapter 3.

While this dissertation was written following a three-paper model, with Chapters 2 through 4

prepared as stand-alone manuscripts, together they provide a comprehensive understanding of

UFMPs, municipal foresters attitudes and actions regarding native tree species and residents’

knowledge, attitudes, and actions regarding native tree species and urban forest issues. The

broader management implications and areas for future research are explored in the concluding

chapter

1.3 The Urban Forest

Urban forests consist of all the trees within a town or city, including street trees, park trees, trees

in remnant wooded areas, other public trees and all private trees (Kenney et al., 2011;

Konijnendijk et al., 2006). A tree is a woody perennial plant that is different from a shrub in that

it is larger at maturity, however, their differences are arbitrary with some sources considering

certain shrubs to be small trees and vice versa (Farrar, 1995; Waldron, 2003). Historically urban

forests have been perceived as having limited ecological value because they are heavily modified

by humans and relatively small in size, making up approximately 4% of land cover worldwide

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(Dobbs et al., 2011). But with rates of urbanization quickly increasing, urban forests are being

recognized for their importance as ecological reservoirs, providing valuable functions and

ecosystem services for much of the world’s population (Davies et al., 2011).

The formal concept of urban forestry was first introduced at the University of Toronto in 1965

(Jorgensen 1970). Jorgensen states that urban forestry deals “with tree management in the entire

area influenced by and utilized by the urban population.” In the case where municipal boundaries

make the forest too large to manage as an urban forest, as is the case with several Canadian

municipalities, the boundaries have been set as the territory in which all homes are serviced with

municipal sewers and water (Duinker et al., 2015).

Urban forests differ from traditional forests in that urban areas are highly managed and contain

environmental stressors that do not directly affect traditional forests, including soil compaction;

limited root volume and pervious surface under the crown of the tree; soil nutrient deficiencies;

and various soil, water, and air contaminants (Day et al., 1995; Gilman, 1988; van Wassenaer

and Kenney, 2000). Trees grow differently in urban forests, often lacking the height and

longevity of their non-urban forest equivalents, and they are often valued for traits other than

ecological integrity or economic gain, e.g. low maintenance, and aesthetics (Quigley, 2004).

Genetic diversity is also different in an urban forest, as commonly planted trees are often clones

of one another, decreasing the resilience of urban forests to biological invasions and other

stressors (Pauleit et al., 2002; Sjoman et al., 2011).

Urban forests differ from the European notion of ‘town forests’ which are woodlands

surrounding a town, owned and managed by the town (Konijnendijk et al., 2006). Typically,

5

definitions of the urban forest do not take into account the numerous other biota and structures

that exist and critically interact with trees in the ecosystem. Rather, the discipline’s niche is the

focus of tree management in urban areas and the unique environmental conditions encountered.

College and university urban forestry and arboriculture programs focus on large scale and

individual tree management (Elmendorf et al., 2005), and in a professional capacity urban

foresters typically have very separate responsibilities from horticulturalists, ecologists, and

biologists.

1.3.1 Benefits of the Urban Forest

Urban forestry emerged from a desire to mitigate the negative effects of the urban environment

on trees, and more recently focused on the numerous economic, social, and ecological benefits

they can provide through their ecosystem services. While trees are associated with disservices

such as the hazard of falling limbs and fruits, allergy-inducing pollen, and blocking road

sightlines (Dobbs et al., 2011; Lyytimäki and Sipilä, 2009), trees tend to be valued by people

(Duinker et al., 2015; Ostoić and Konijnendijk, 2015), and many studies demonstrate the

plethora of ways in which trees provide ecosystem services that benefit cities.

In terms of environmental benefits, trees cool, filter, and improve air quality in the city, reducing

atmospheric carbon and particulate matter (Smith, 1990) while mitigating the urban-heat-island

effect (Livesley et al., 2016) through shading surfaces, transpiration of water vapor, respiration,

and reduction of solar radiation (Heisler, 1990). They help prevent erosion and flooding as their

roots stabilize soil and absorb ground and surface water (Neville, 1996; Sanders, 1986; Xiao et

al., 1998). Urban trees also improve water quality by reducing the flowrate of stormwater, and

staggering its’ outflow to waterbodies (Xiao et al., 2000).

6

Social benefits of urban forests include enhancing people’s sense of place (Elmendorf, 2008;

Hull et al., 1994) and community safety (Kuo et al., 2001), while providing recreational

opportunities (Bolund and Hunhammar, 1999; Gobster and Westphal, 2004). Benefits also

include mental health and wellbeing (Lee and Maheswaran, 2011; Ulrich 1981; Ulrich, 1984), as

several studies have shown that individuals have experienced shorter hospital stays and positive

physiological effects when exposed to a greener built environment (Rubin et al., 1998).

Trees are also economically beneficial. They have been found to increase property value (Anthon

et al., 2005; Kong et al., 2007; Tyrväinen, 1997), business traffic (Wolf, 2004), tourism

(Majumdar et al., 2011), longevity of infrastructure (McPherson and Muchnick, 2005), and

employment opportunities (Duinker et al., 2015). They can also reduce energy costs related to

summer cooling and/or winter heating, depending on the orientation of trees near buildings

(Akbari and Taha, 1992; Nowak and Dwyer, 2007). When cities invest in trees, they are

supporting several industries such as tree care, nursery, and urban forestry professions.

Additionally, there is a large bird-feeding economy that is dependent upon tree habitat for birds

(Degraff and Payne, 1975).

Finally, urban forests provide opportunities to learn about and conserve biodiversity and wildlife

habitat (Alvey, 2006). Cities disproportionately occur in areas of high biodiversity (Kuhn et al.,

2004), and many contain rare and endangered species for which measurable efforts have been

expended to conserve them (Alvey, 2006; Colding et al., 2003; Gustafsson, 2002). The high

visibility and complexity of many urban forest ecosystems make them excellent forums for

environmental education (Dwyer and Schroeder, 1994), and learning in a green environment has

been shown to improve children’s learning and behaviour in urban areas (Wells, 2000).

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Though numerous studies have documented urban forests positive contribution to urban areas

and their residents, knowledge gaps remain in terms of how to develop policy that will support

the long-term sustainability of urban forests; whether ecological integrity, ecosystem services, or

adaptation to future climates should be prioritized and how that may alter practice; and the role

of native species in urban forest management. In southern Ontario, municipalities are addressing

long-term management of the urban forest through their UFMPs, though few studies have

examined the rationales and impacts of these plans given their recent adoption.

1.4 Urban Forest Theory and Concepts

1.4.1 Native Species in the Urban Forest

Prevailing ecological theory attributes the formation of ecosystems to the co-evolution of species

over millennia (Ehrlich and Ehrlich, 1981), and that large-scale patterns primarily result from,

rather than drive, evolution at lower levels (Levin, 1999). According to this view, by competition

and co-adaptation over time, species partition all available niches and produce stable

communities. Co-adapted, or native, species have increased resilience to disturbances in the

ecosystem and are generally considered more beneficial to that ecosystem (Rotherman and

Lambert, 2013). However, the native status of a species is not always agreed upon, as nativeness

is a social construct. For example, some define a native species as one that arrived in the region

before neo-lithic times, or arrived since without human agency (Kendle and Rose, 2000).

However, another commonly espoused definition of a native species in North America is a

species that was extant prior to 1492 when Christopher Columbus arrived. This definition

ignores the influence of Aboriginal peoples, who managed the composition of the forest, planting

beneficial fruit and nut trees long before 1492 (Waldron, 2003).

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Given the various definitions of native species, people occasionally disagree as to which species

are native (Sagoff, 2005; Smout, 2000). Furthermore, Earth is not characterized by homeostasis.

It is a dynamic system whose geological, climatic, and biological make-up have fluctuated since

its genesis, and some argue that these varying degrees of change and development mean that we

should observe varying levels of nativeness, including old, naturalized, and recent non-native

species (Ordóñez and Duinker, 2012). Moreover, urban species assemblages are often

reorganized in ways that emphasize a species resilience to urban stressors as opposed to its

native status (Angermeier, 1994; Sjoman and Nielsen, 2010).

Urban ecosystems actually have some of the highest levels of tree species richness on the planet

(Alvey, 2006; Clemants and Moore, 2003; McKinney, 2002; Nowak, 1993), not only because of

naturally occurring tree diversity, but also species introductions, and native and non-native

species plantings. In some cases, urban areas that were considered species-poor prior to urban

development are now comparatively species-rich, such as North American prairie cities and parts

of California, which has notably increased from 10 native tree species to more than 350 species

in little over a century’s time (Kurz and Baudains, 2012; Nagendra and Gopal, 2011; Nowak,

1993; Nowak, 2012). Conversely, there are also examples of urban areas that have a diminished

number of species compared to pre-urbanization assemblages, such as Rio de Janeiro (Bertin et

al., 2005; dos Santos et al., 2009).

Though species assemblages in urban ecosystems contain many non-native species, urban

ecosystems are not isolated from surrounding natural ecosystems, and are in fact very diffuse

(Bolund and Hunhammar, 1999). Constant ecological interactions between urban, peri-urban,

9

rural and natural areas occur, and urban ecosystems have the potential to be, and oftentimes are

important native species strongholds (Raupp et al., 2006; Ricotta et al. 2010).

The importance of maintaining native species within urban forests is unclear (Alpert et al., 2000;

D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff, 2005). The current understanding of

ecological integrity suggests that native species should be prioritized (Alvey, 2006; Ordonez and

Duinker, 2012; Raupp et al., 2006), but the benefits of planting at least some non-native species,

and the potential of assisted migration in urban forests as a response to climate change raise

questions about the value of a native-only (or native-first) approach to tree planting. These

concepts, and their relationships with native species in the urban forest are discussed below.

1.4.2 Ecosystem Services and Ecological Integrity

The literature examining urban forest management focuses on managing for ecosystem service

provision and ecological integrity. Ecosystem services are the goods or services provided by

ecosystems that contribute to human well-being (MEA, 2005). The well-documented services

provided by urban forests include storm water retention, erosion control, microclimate

regulation, and improved human physical and mental health (Ostoić and Konijnendijk, 2015).

They are correlated with biodiversity, such that higher diversity yields a greater amount of

services (Dobbs et al., 2010; Escobedo et al., 2011; Ordonez and Duinker, 2012). However,

diversity of native species may not be required for a high level of ecosystem service provision

(Morgenroth et al., 2016).

Ecological integrity is a macro-scale concept measuring the wholeness and proper functioning of

an ecosystem (Bolund and Hunhammar, 1999; Clemants and Moore, 2003; Hermoso and

10

Clavero, 2013; Landry and Chakraborty, 2009; Ordóñez and Duinker, 2012). When ecosystem

functions are lost due to an absence of native diversity, the system becomes less resilient, so the

capacity to resist damage and recover from a disturbance is reduced (Folke et al., 2004). The

current composition of species in most urban forests means that some functions (e.g. provision of

food, maintaining biodiversity, nutrient cycling, reduction of wind damage, regeneration of soils

and the maintenance of organisms within them) do not occur at the same rate as forests with a

high ratio of native species, suggesting lower resilience and reduced integrity (Ordóñez and

Duinker, 2012).

The inability of an urban ecosystem to support specialist or rare species also reflects a lack of

ecological integrity (McKinney, 2002), since certain structural components of forest ecosystems

are lost in this way. Over the past century in North America entire genera of common urban trees

have also been annihilated by invasive biota (Castanea, Ulmus, Fraxinus), which has resulted in

replanting with a low diversity of trees, continuing to leave urban forests susceptible to large-

scale pest invasions. Urban forest resilience can be theoretically heightened by planting a higher

diversity of tree families, genera, and species to lower the risk of mass tree losses (Raupp et al.,

2006).

All urban forests couple natural development processes and human processes, necessitating a

trade-off between these different processes (Ordóñez and Duinker, 2010). Urban forests are

largely engineered to provide services for society with an immediacy that natural forests do not

replicate. Furthermore, in some regions there may be a limited catalogue of native species that

can fulfill ecosystem services and are resilient to harsh urban ecosystems conditions (Sjoman et

al., 2016). As such, street trees are often chosen for attributes that contribute ecosystem services,

11

but diminish ecological integrity because trees planted to maximize immediate services tend to

lack longevity, large stature, and native status (Nowak et al., 2003).

1.4.3 Assisted Migration

In addition to ecosystem services and ecological integrity, assisted migration is emerging in the

literature as a possible management strategy. Assisted migration, also known as managed

relocation, is the intentional translocation of tree species outside of their historic ranges in order

to ameliorate actual or anticipated effects of climate change (Hewitt et al., 2011). While all

species have some natural capacity to migrate into new habitats and evolve to environmental

changes, ongoing anthropogenic climate change is occurring too rapidly for many tree species to

migrate naturally (Zhu et al., 2012). Thus, in an attempt to preserve biodiversity and maintain

coevolved species assemblages, some ecologists and practitioners have begun to assist the

dispersal of species to higher elevations and historically cooler ecozones (McLachlan et al.,

2007).

Assisted migration as a tool for addressing climate change is most commonly practiced within

the forestry sector. For example, the western Canadian provinces of British Columbia and

Alberta have modified their forestry seed transfer guidelines to allow seeds to be planted 200

metres higher in elevation and two degrees of latitude northward for most tree species (Pedlar et

al., 2012). However, the debate around assisted migration remains primarily conceptual, as many

of the anticipated aspects of climate change have yet to happen, delaying the ability to measure

the success of these practices.

12

The risks of assisted migration include accidentally introducing new invasive species,

challenging established conservation priorities, tree mortality and investment loss, and

consuming resources addressing the symptoms of climate change, rather than causes (Hewitt et

al., 2011; McLachlan et al., 2007). However, assisted migration may also lead to healthier urban

forests and ensure that rare and endangered trees otherwise unable to migrate quickly may still

survive (Hewitt et al., 2011).

Urban ecosystems are considered suitable pilot areas for assisted migration because they already

tend to be ‘novel’ ecosystems with long histories of exotic species plantings, and non-native

species assemblages (Hobbs et al., 2006; Kowarik, 2011), and not as likely to be negatively

affected by non-native species. Additionally, the urban heat-island effect elevates the

temperature in urban areas in comparison to surrounding areas (IPCC, 2001), allowing for

species that are less tolerant of the cold to flourish (Imhoff et al., 2010). Due to the anticipated

consequences of climate change, some urban foresters are choosing to plant species that have

evolved in warmer climates in preference of native species at the southern extent of their range.

Since many species of trees have considerable longevity, and even the most conservative climate

change estimates indicate warming by at least 1.7ºC by mid-century (Meehl et al., 2007), this

will likely affect the survivability of trees evolved in cooler climates. Thus, managing for climate

conditions 20-plus years in the future, means considering planting trees that evolved in warmer

climates.

Though studies of assisted migration, ecosystem services, and ecological integrity have recently

been increasing, previous studies of assisted migration and considerations of ecological integrity

13

have lacked a practical component examining how these practices are incorporated into urban

forestry policy and practice.

1.5 Urban Forest Stakeholders

1.5.1 Municipalities and UFMPs

Urban forest structure is shaped by the many actions of different stakeholders. In North

American municipalities, municipal governments are responsible for the care and maintenance of

trees located in parks, other municipal land and along streets (City of Burlington, 2010; City of

London, 2014; City of Mississauga, 2014; City of Toronto, 2013; Town of Oakville, 2008). In

smaller municipalities, they may employ an arborist or tree-care company who will act in their

interest (Town of Oakville, 2008).

Municipal trees are a public good, and municipalities tend to select tree species to maximize

ecosystem services and minimize disservices. At the decision-level, disservices tend to outweigh

ecosystem services; if trees have thorns (Gleditsia, Crataegus), or large nuts that may damage

property (Juglans, Carya), if the tree is structurally weak (Populus), or has problematic roots

(Salix), or if the tree blocks sightlines (Thuja, Picea, Abies, Pinus) then it will not be selected for

planting as a street tree in most municipalities (Nowak et al., 2003).

Municipalities recognize that urban street trees face several adverse conditions and successfully

identifying tree species that will thrive consistently is a challenge. Given budgetary constraints,

lack of species’ suitability trials, and low odds for long-term survival, urban street trees are often

chosen from a small list of trees that are known to tolerate most urban stressors. Many of these

14

trees are non-native. In southern Ontario they have been the Gleditsia triacanthos x shademaster

(shademaster honey locust), Acer platanoides (Norway maple), Acer x freemanii (freeman

maple), Fraxinus pennsylvanica (green/red ash), Platanus x acerifolia (London planetree), Acer

saccharinum (silver maple), Pyrus calleryana (callery pear), Gingko biloba (gingko), Acer

saccharum (sugar maple), and Tilia cordata (little-leaf linden) (City of London, 2014; Town of

Oakville, 2008). Moreover, municipalities are often not involved in choosing the tree species

planted in planned developments, leaving that to developers who have traditionally bought a few

species of inexpensive trees and planted them throughout the development (Nowak et al., 2003).

An UFMP is a document purposefully created to increase urban forest management effectiveness

and efficiency, improve tree health, minimize risks to the public and maximize the ecosystem

benefits provided by the urban forest (City of Burlington, 2010). UFMPs have recently been

adopted by several North American municipalities as a way of justifying budgets and staffing for

urban forestry programs, and to increase tree cover and diversity (Kenney et al., 2011; Ordóñez

and Duinker, 2013). Typically, they are 20 year plans that are subdivided into four 5-year plans,

with objectives and targets to be met, or reassessed annually and at the end of each 5-year plan.

The content and structure of UFMPs varies depending on the municipality and its urban forest

goals, but the majority of plans include considerations of: 1) management and implementation,

2) tree health and risk management, 3) protection and preservation, 4) replenishment and

enhancement, and 5) public outreach and stewardship. Though UFMPs are drafted by the

municipality, they depend upon partnering with residents to achieve many of the urban forest

goals within them.

15

Since urban forests are also shaped by natural forces, they require forethought to manage

proactively, such that costs for maintaining and sustaining them are established in advance, to

potentially mitigate unforeseen circumstances (Kenney and Puric-Mladenovic, 2001). For

example, cost overruns for managing the emerald ash-borer infestation in eastern North America

could have been lessened had urban forests been managed to have higher tree diversity,

comprising of both evenness and greater species richness, which would have meant fewer ash

tree removals, where in some cities ash comprised nearly 50 percent of the street tree

composition (Town of Oakville, 2008). Subsequently, many municipalities have had to expend

extra money to save large trees, and remove numerous dead or dying trees. Some budgetary

stress could have been avoided by adhering to rudimentary forestry principles which can be

codified in an UFMP, like the 10:20:30 rule, that states that the street tree population of a

community should consist of no more than 10% of a single tree species, 20% of a single genus,

and 30% of a single family (Kenney et al., 2011; Sydnor et al., 2010).

In one of the few studies examining UFMPs, Ordóñez and Duinker (2013) found many

management topics in common with the majority of UFMPs, but the only topic common

amongst all UFMPs in Canada was consideration for native tree species. However, Ordóñez and

Duinker’s (2013) study did not explore the implementation impacts on municipal foresters and

residents related to these plans. Thus, notable knowledge gaps exist regarding UFMPs, including

urban forestry staff’s willingness to adopt UFMP goals, it’s influence on residents’ knowledge,

attitudes, and actions regarding urban forest issues, and other long-term impacts of managing a

municipality’s urban forest with an UFMP.

16

1.5.2 Residents and the Urban Forest

Another major stakeholder of the urban forest is residents, who have become a recent focus of

urban socio-ecological and urban forest studies. The role of urban residents in shaping and

managing the urban forest is less understood than that of the municipality, because their greenery

choices go largely undocumented, there is no mandate for landowners to plant trees, and

individual residents have unique aesthetic tastes (Conway and Urbani, 2007; Pataki et al., 2011).

However, residents are perhaps the most important variable regarding urban forest health, as it is

estimated that 75% of urban trees are on private property, and that 75% of those are planted by

residents (Nowak, 2012). This means that in order to affect large-scale change in the urban

forest, policy and law makers must be able to influence the planting actions and attitudes of

residents.

Recent research has begun to focus on where trees are located in relation to residential

characteristics, who is likely to participate in tree planting programs, and some basic attitudes

that residents have towards trees. Residents’ socioeconomic characteristics are related to the

actual distribution of the urban forest, as areas with higher percentages of owner-occupied

homes, fewer visible minorities, and residents with university degrees and higher incomes

generally have more canopy cover (Grove et al., 2006; Heynen et al., 2006; Landry &

Chakraborty, 2009; Pham et al., 2012; Tooke et al., 2010).

Additionally, there is some evidence that tree-planting actions vary among residents based on

their socioeconomic characteristics. Perkins et al. (2004) and Greene et al. (2011) both found that

participants in tree planting programs were more likely to be white homeowners, from

neighbourhoods with high socioeconomic status. People with higher income and education-

17

levels between the ages of 30 and 49 are most likely to participate in general urban forestry

activities (Fleming et al., 2006).

Given the patterns of uneven canopy cover and planting activity among different socioeconomic

groups, there are concerns that not all socioeconomic groups receive the same benefits associated

with the urban forest, potentially creating inequities within cities (Heynen et al., 2006). However,

Pham et al. (2012) determined that physical space constraints often underlie uneven distributions,

suggesting that trees in low income, renter dominated areas may be hampered by a lack of

available planting sites. While not eliminating inequalities it suggests differences are not directly

because of socioeconomic conditions themselves.

Residents’ perceptions about urban forest issues, including invasive species, canopy cover, and

biodiversity can affect planting habits on their property. In Australia, Kirkpatrick et al. (2012)

found that residents’ attitudes towards flora tend to be expressed in action on their property such

that, if residents appreciated native flora, they tended to plant native flora. In a study of residents

in Perth, Australia, the attitudinal variable with the strongest relationship to garden-type

preference was residents’ attitude toward native plants (Kurz & Baudains, 2012). Preferences

were also highly related to prevailing gardening norms in respondents’ local area.

Much of the urban forest is controlled by individual residents. Socioeconomic characteristics,

attitudes and knowledge affect residents’ planting actions and support for urban forestry efforts,

but it is unknown what residents’ knowledge, attitudes and actions towards native species in the

Eastern North America are, and whether or not UFMPs are playing a role in shaping knowledge,

attitudes and actions.

18

1.6 Study Area – Carolinian Canada

This study focuses on municipalities’ native tree species management and residents’ knowledge,

attitudes and actions regarding native trees within the Carolinian Zone of Ontario, Canada

(Figure 1). The region is Canada’s most densely populated, with greater than 8 million people

living in one-quarter of one percent of the country’s land area (Reid, 2002; Statistics Canada,

2011). Moderated by the proximity of the Great Lakes, the Carolinian Zone’s climate is

characterized as humid continental (Koppen Dfa to Dfb) with four distinct seasons (Ontario

Climate, 2011). The region’s vegetation is unique within Canada, characterized by broadleaf-

deciduous trees like Sassafrass albidum (sassafrass), Gymnocladus dioicus (Kentucky

coffeetree), Liriodendron tulipifera (tuliptree) and Magnolia acuminata (cucumber magnolia),

while also representing the southern extent of the Great Lakes-mixed boreal forest. As a result, it

is a biodiversity hotbed with the highest species richness of any ecozone in Canada (Johnson,

2007). Historically, this region’s land cover was 80% forest, which now only occupies 11% of

the landscape (Johnson, 2007). Due to the unique ecology and conditions in the Carolinian Zone

there are on-going efforts to protect the native species assemblage (Johnson, 2007; Ministry of

Natural Resources, 2000; Reid, 2002; Waldron, 2003). Specific municipalities included in the

analyses addressing each objective of the thesis are described in detail in the relevant chapter.

19

Figure 1 – Map of the Carolinian forest zone in Canada showing municipalities in the study area

.

20

Chapter 2

The Role of Native Species in Municipal Urban Forest

Planting and Practice: A Case Study of Carolinian Canada

2.1 Introduction

Throughout North America municipalities are adopting strategic plans and ambitious tree

planting goals based on the numerous ecological, social, health and economic benefits ascribed

to the urban forest. This parallels recent foci of urban environmental research exploring

sustainable management of urban forests (Clark et al., 1997; Kenney et al., 2011; Mincey et al.,

2013; Vlek and Steg, 2007; Young, 2013) and documenting their ecosystem services (Alvey,

2006; Bolund and Hunhammar, 1999; Nowak and Dwyer, 2007). With the aggressive planting

goals many municipalities are pursuing, species selection today will have a lasting impact on the

composition, health, and function of the urban forest.

Urban forests typically have relatively high species richness as compared to the surrounding

countryside (Alvey, 2006; Bertin et al., 2005; Miller and Hobbes, 2002; Stewart et al., 2004).

However, this richness is often the result of numerous non-native species while many native tree

species are not regularly planted (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and

Rose, 2000; Schaeplfer et al., 2012). The importance of maintaining native species within urban

forests is unclear, as there is a knowledge gap surrounding the tolerance of many tree species to

urban stressors (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff, 2005).

The current understanding of ecological integrity, measured as the wholeness and proper

functioning of an ecosystem, suggests that native species should be prioritized (Alvey, 2006;

21

Ordóñez and Duinker, 2012; Raupp et al., 2006), but the benefits of planting at least some non-

native species, and the potential of assisted migration in urban forests as a response to climate

change raise questions about the value of a native-only (or native-first) approach to tree planting.

To guide urban forestry, municipalities are increasingly adopting urban forest management plans

(UFMPs), which typically outline management goals and objectives over a 20-year timeframe.

Ordóñez and Duinker (2013) found the one commonality among all of the existing Canadian

UFMPs was an emphasis on planting native species. It is unclear if and how debates associated

with assisted migration, defined as the intentional translocation of species outside of their

historic ranges in order to ameliorate actual or anticipated biodiversity losses (Hewitt et al.,

2011; McDonald-Madden et al., 2011; McLachlan et al., 2007; Ordóñez and Duinker, 2014; Sax

et al., 2009; Zhu et al., 2012), and the potential benefits of planting non-native species, including

tolerance for urban stressors and provision of desired ecosystem services, have influenced the

goals in these plans, or the impact such debates and UFMPs themselves have on actual planting

practice.

Given the gaps in our understanding of the formulation and implementation of UFMPs and on-

going discussions about ecological integrity, non-native species benefits and assisted migration,

the objectives of this study are to (1) examine the role of native species in UFMPs; (2) explore

municipal foresters’ attitudes and actions related to native tree species, and (3) explore if

municipalities with and without formal management plans are making different decisions

regarding native tree species planting. These objectives are addressed through a case study of

municipalities in Carolinian Canada (Ontario, Canada), a region with relatively high native tree

richness, by examining UFMPs and interviewing urban foresters from municipalities with and

22

without UFMPs. The following sections outline debates around native and non-native species in

urban forests, present our methods and results, and provide a broader discussion of the

implications of current practice and recommendations for future urban forest management.

2.2 Ecological Integrity, Assisted Migration, and Non-native Trees in the

Urban Forest

The recent urban ecology and urban forestry literature debates the value of native trees in cities,

in part, because of the unique conditions associated with urban forests (Hitchmough, 2011;

Kendle and Rose, 2000; Kowarik, 1995; Rotherman and Lambert, 2013). In particular, the

importance of and potential pathway to achieve ecological integrity, the useful role of planting

non-natives trees, and the use of assisted migration as a tool to mitigate and adapt to climate

change have all been discussed (Camacho, 2010; Davis, 2012; Hewitt et al., 2011; Ordóñez and

Duinker, 2012; Zhu et al., 2012).

Ecological integrity depends upon a high ratio of native biodiversity (Bolund and Hunhammar,

1999; Clemants and Moore, 2003; Hermoso and Clavero, 2013; Landry and Chakraborty, 2009;

Ordóñez and Duinker, 2012). When ecosystem functions are lost due to an absence of native

diversity, the system becomes less resilient, so the capacity to resist damage and recover from a

disturbance is reduced (Folke et al., 2004). The current composition of species in most urban

forests means that some functions (e.g. provision of food, maintaining biodiversity, nutrient

cycling, reduction of wind damage, regeneration of soils and the maintenance of organisms

within them) do not occur at the same rate, suggesting lower resilience and reduced integrity

(Ordóñez and Duinker, 2012).

23

In order to improve the ecosystem function and resilience of urban forests, it is important to plant

not only a diverse assemblage of trees – which often already exists – but a diversity of native

trees. More specifically, native specialist and rare species must be present in order to support a

high degree of ecological integrity (Ordóñez and Duinker, 2012). However, while generalist

species can often survive the many stressors present in urban ecosystems, specialized and/or rare

native species frequently cannot (Ordóñez and Duinker, 2012). The unique challenges of

managing such a system – typically including high levels of impervious surfaces, variable

amounts of shade/sunlight, highly compacted soils, lower air quality, and other molestations –

creates complications for prioritizing native tree species, such that tree species tolerant of urban

stressors are preferred for planting even if they are not native (Escobedo et al., 2011).

Furthermore, municipalities are tasked with not only maintaining and enhancing ecological

integrity, but also typically need to reduce tree-related risks while increasing the ecosystem

services provided by the urban forest (Kenney et al., 2011). Risks are reduced, in part, by

planting trees without large fruits/nuts, avoiding the use of softwood and coniferous trees as

street trees, and using small trees to avoid utility conflicts (City of Burlington, 2010), thus

potentially excluding a number of native species.

Ecosystem services are defined as the goods or services provided by ecosystems that contribute

to human well-being (MEA, 2005). The well-documented ecosystem services provided by urban

forests include storm water retention, erosion control and microclimate regulation (Ostoić and

Konijnendijk, 2015). Managing for ecosystem service provision and risk reduction is often

achieved by planting trees that are assured to grow quickly with minimal need for maintenance

and other capital expenditures, regardless of their native status (Dobbs et al., 2011; Sjoman and

24

Nielsen, 2010). For instance, Acer platanoides (Norway maple) and Platanus x acerifolia

(London plane) have been frequently planted in urban areas outside their native ranges due to

their relatively fast growth; resistance to pests; and ability to withstand urban stressors, such as

soil compaction and particulates. In at least some cases non-native species are better at

providing desired ecosystem services in urban environments (Escobedo et al., 2011), including

providing habitat and food sources for native species (Gray and van Heezik, 2016). Given the

novel assemblages of species already present in most cities, some have argued that exotic species

should not be avoided simply because of their non-native status (Kowarik, 2011).

While some non-native trees may be more tolerant of certain urban stressors and survive better

as a result, individual trees are part of the larger urban ecosystems. The resilience of these

ecosystems to recover from disturbances, as well as the provision of food for other parts of the

food-web, nutrient cycling, and soil creation are dependent on native trees. Thus, a dilemma

exists regarding an appropriate emphasis on native species, whose planting can increase

ecological integrity, while planting select non-native species may ensure a better survival rate in

stressed situations, reduce risks to people and property, and quickly provide key ecological

services.

Further complicating the appropriate ratio of native species in urban forests is the likely inability

of many tree species to rapidly adapt to the changing climate (Zhu et al., 2012). Given the long

life-span of trees, planting decisions today will influence urban forests’ species composition for

years to come, but some native species may not be able to survive in their current ranges in the

coming decades. Assisted migration is one way to maintain healthy urban forests into the future

25

in light of anticipated climate change (City of Halifax, 2012; Kowarik, 2011; Ordóñez and

Duinker, 2013; Peel, 2011).

The term assisted migration is discussed in the literature in a variety of ways (Hewitt et al., 2012;

Pedlar et al., 2012; Ste-Marie et al., 2011). In this study, we focused on assisted migration as the

intentional translocation of species outside their historic ranges (typically shifting northward) in

order to ameliorate actual or anticipated biodiversity losses caused by climate change, similar to

the way the term is used in the forestry sector (Pedlar et al. 2012). This may entail moving

individuals to locations with species assemblages that have coevolved with the relocated species

or to locations with non-coevolved species assemblages (Hewitt et al., 2012). In Carolinian

Zone urban forests, there is the potential for both approaches to be used to maintain the forest

over the long-term in light of climate change, by planting species from the Eastern Deciduous

Forest with ranges that do not current extend northward into Ontario. There is also the prospect

of introducing varieties or cultivars of native species that have evolved in a warmer climate.

Assisted migration as a tool for addressing climate change is perhaps most commonly practiced

within the forestry sector. For example, the western Canadian provinces of British Columbia and

Alberta have modified their forestry seed transfer guidelines to allow seeds to be planted 200

metres higher in elevation and two degrees of latitude northward for most tree species (Pedlar et

al., 2012). However, the debate around assisted migration remains primarily conceptual, as

many of the anticipated aspects of climate change have yet to happen, delaying the ability to

measure the success of these practices.

26

Assisted migration is a complex topic rife with ethical, economic, legal, political, and ecological

issues (Schwartz et al., 2012). These include the impact of the introduced species on the hosting

environment, the potential of a species becoming invasive, and mortality and investment loss if

the species is not well adapted to the local conditions. In short, it disrupts widely held

conservation objectives and paradigms (McLachlan et al., 2007). In order to ensure that assisted

migration is beneficial and that risks are minimized, decisions should be supported by scientific

findings, with migrated populations and the receiving ecosystems carefully monitored over time

(Sax et al., 2009).

Urban ecosystems are potentially good locations to apply assisted migration as a climate change

tool because the urban heat-island effect already elevates the temperature as compared to

surrounding hinterlands, potentially allowing less hardy species to acclimatize to more northerly

latitudes (Imhoff et al., 2010). Additionally, the high number of planted non-native trees means

that urban ecosystems are already ‘novel’ systems (Hobbs et al. 2006; Kowarik, 2011), with

species assemblages created through long histories of exotic species introductions.

While assisted migration is used to describe intentional management practice, in many urban

areas passive or unintentional assisted migration is already occurring as a result of the supply of

nursery stock and tradition of using exotic species as landscaping elements (Hitchmough, 2011).

However, it is unclear the extent to which municipalities are actively adopting assisted migration

as part of climate change strategies, and how active and passive assisted migration practices are

impacted by native species goals.

27

2.3 Methods

2.3.1 Study Area

As described in Chapter 1 this study focuses on municipalities’ native tree species management

within the Carolinian Zone of Ontario, Canada (Figure 1).

The nine urban municipalities within the Carolinian Zone that had an UFMP enacted by city

council as of April 2015 were included in the study (Table 1). The City of Guelph and the Town

of Ajax are on the outer boundaries of the Carolinian Zone, but were included as Carolinian

municipalities because of the numerous Carolinian tree species planted there, as well as the

anticipated northward progression of typical Carolinian species. Additionally, the 11 most

populous municipalities within the zone that lack an UFMP were included (Table 2), to provide

insight into the similarities and differences in municipal attitudes and actions between

municipalities with and without an UFMP. Collectively, these municipalities represent a variety

of urban forms and urban forest conditions. Based on the 2001 Ontario Municipal Act, the

municipalities all have the responsibility to manage street trees and other trees on municipal

land, as well as the ability to regulate trees on private property.

28

Table 1 Carolinian Zone municipalities with an Urban Forest Management Plan

Municipality (Year UFMP enacted)

Population (Statistics Canada, 2011)

Municipality Type (Municipal Act, 2001)

Ajax - (2011) 110,000 Lower-tier

Brantford - (2010) 95,000 Single-tier

Burlington - (2011) 180,000 Lower-tier

Guelph - (2012) 125,000 Single-tier

London - (2014) 370,000 Single-tier

Mississauga - (2014) 720,000 Lower-tier

Oakville - (2008) 185,000 Lower-tier

St. Catharines - (2011) 135,000 Lower-tier

Toronto - (2013) 2,650,000 Single-tier

Table 2 Carolinian Zone municipalities included in the study that were contacted for an

interview but have not enacted an Urban Forest Management Plan as of March 2015

Municipality with

no UFMP

Population (Statistics Canada, 2011)

Interviewed

Cambridge 126,748 Yes

Markham 301,709 Yes

Milton 84,362 Yes

Niagara Falls 82,997 Yes

Brampton 523,911 No

Chatham-Kent 103,671 No

Hamilton 519,949 No

Kitchener 219,153 No

Sarnia 72,366 No

Windsor 210,891 No

Woodstock 37,754 No

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2.3.2 Urban Forest Management Plan and Planting List Review

Copies of the nine Carolinian Zone municipal UFMPs were acquired. The documents range from

46 (City of London, 2014) to 213 pages (Town of Oakville, 2008) in length and were adopted

between 2008 and 2014. Each document was analyzed for the following terms: native, non-

native, invasive, and exotic. When found, the context that the term was used in was recorded.

Additionally, municipal tree species planting lists were acquired from study municipalities with

and without UFMPs to determine the species regularly planted. The lists provide insight into

how well the urban forest goals outlined in the UFMPs are aligning with the planting practices of

the municipality or, in the case of municipalities without an UFMP, the stated goals associated

with the urban forest. Drafting and updating the lists are the responsibility of the municipalities’

Director of Forestry or equivalent, and these lists were drafted independently of the UFMP. Each

list was examined to determine the percent of native species per list and the percent of native

species that appeared on at least one municipal list was also calculated. Native status was

identified using Waldron (2003).

2.3.3 Interviews

The influence of UFMPs on urban foresters whose job it is to carry out municipal tree planting

and site-level species selection decisions has been largely unexamined. In this study, interviews

were employed to explore how municipal urban foresters view the role(s) of native species in the

urban forest in light of current debates surrounding ecological integrity, the benefits of non-

native species, assisted migration, as well as criteria used to select specific species to plant at a

given site.

30

During the first half of 2015, email and telephone outreach was conducted to contact an urban

forestry representative from each of the nine municipalities in the Carolinian Zone with an

existing UFMP, as well as the eleven most populous municipalities that lack such a plan. After

contact with the municipal representative was established, a mutually agreed upon time was set-

up for the interviews. Interviews occurred over the telephone or in-person, taking about one

hour to complete. Representatives from all municipalities with an UFMP were interviewed, but

we were only able to interview seven of the eleven contacted municipalities without an UFMP.

Of these seven municipalities, four had a draft UFMP submitted to city council. The remaining

four were contacted up to five times but expressed a lack of interest or never responded to our

requests.

All 16 interviewees had a unique job title, reflecting the size and organization of their

municipality and their specific responsibilities. These ranged from Manger of Forestry to City

Arborist to Manager of Environmental Services. However, all participants were involved in tree

planting and selection decisions, overseeing the day-to-day management of their municipality’s

urban forest. The range of employment longevity in the participants’ current position spanned

from one to 30 years, and their educational backgrounds included forestry, horticulture,

environmental science, arboriculture, and landscape architecture.

A semi-structured approach was used in the interviews, focusing on understanding the rationale

behind the treatment of native species in the UFMP and municipal planting practice. For the

municipalities that did not have an UFMP, the interviewees were asked about other forms of

forestry planning and outreach they conduct. The interviews were organized around questions

pertaining to: the value(s) each department associates with native species; the prevalence of

31

native species in municipal planting practices; where the tree species are obtained from and the

provenance of the trees (since tree suppliers can also affect what trees are planted); issues with

supply; in what case native species are preferred to non-native species (and vice-versa); whether

or not assisted migration is being taken into consideration; and if they believe recent planting is

addressing the goals and objectives of the UFMP (when applicable). At the start of the

interview, we defined several terms for the interviewees (Table 3) to ensure a basic knowledge of

each concept and consistent interpretation.

Table 3 Terms that were defined for the interviewees for ideological consistency

Term Defined for Interviewees Definition Provided

Assisted Migration

Assisted migration is the intentional

translocation of species outside of their

historic ranges in order to ameliorate actual or

anticipated biodiversity losses caused by

climatic change.

Ecological Integrity

Ecological Integrity is a measure of the

wholeness and proper functioning of an

ecosystem’s structure and natural processes.

Native Species

Native species are defined as a species that

occurs naturally within a region, either

evolving there or arriving and becoming

established without human assistance.

Tree

A tree is a woody perennial plant, having

trunk greater than 10 cm (4 inches) in

diameter.

32

We followed an informed consent process with all participants, which included giving

respondents the choice to remain anonymous. All interviews were then recorded, with

permission, and transcribed. Transcripts were coded based on an informal review of the content

of the interviews, with NVivo 10 software used to help analyze the range of responses given for

each question.

2.4 Results

2.4.1 Urban Forest Management Plans and Planting Lists

The reasons stated by the interview participants for enacting an UFMP were because it increases

the effectiveness and efficiency of managing the urban forest (five of nine respondents), it

provides clear direction for management (four of nine respondents), city council requested it

(three of nine respondents), and there was a desire to maintain natural heritage (one of nine

respondents). All representatives from the seven municipalities that lack an UFMP stated they

believe that their municipality would benefit from having an UFMP, with four of those

municipalities in the process of adopting one.

Municipal foresters communicate with residents in various ways to consult with and inform them

about urban forest issues and the goals of the UFMP. The most prevalent methods for resident

outreach are: referring residents to their website (10 of 16), social media outreach such as

facebook and twitter (nine of 16), educational booths at special events (six of 16), public

meetings (six of 16), and tree planting events (six of 16). Ten of 16 municipalities also attempt

to educate homeowners about tree selection and care when planting a street tree in front of their

residence. When drafting their UFMP only two municipalities indicated that they did not consult

33

with residents, while seven conducted community and stakeholder meetings prior to drafting

their UFMP. Every municipal forester acknowledged that resident support for urban forestry

goals is crucial for realizing the goals of the forestry department.

In terms of content, all nine UFMPs emphasized the importance of native species in the core

goals and objectives, including a desire to increase the proportion of native species in the urban

forest. For example, Mississauga’s UFMP (2014, p.88) states one of its objectives is the

“preservation and enhancement of local natural biodiversity by increasing the proportion and

population of site-appropriate native plant species through policies, guidelines, management and

stewardship,” while Guelph’s UFMP (2012, p.22) states that “the goal of good forest

management is generally to protect and expand native species diversity so that the area is

intrinsically more resilient to natural and anthropogenic stressors, such as climate change.”

While the UFMPs discuss native trees and their intrinsic benefits, they all lack specificity and

operational clarity; there is no instance of targets for native to non-native ratios for planting,

number or percent of native species that should be present, or situations where only native or

mostly native species should be planted on the streetscape. For example, Toronto’s UFMP states

that “supporting, sustaining and encouraging native biodiversity through management of natural

areas helps maintain the integrity of Toronto’s natural systems for all life forms that depend on

these areas (City of Toronto, 2013, p.24),” but concrete targets related to native biodiversity

levels are not given. While Ajax’s UFMP defines a goal to “increase native biodiversity, and

reduce the risks presented by trees on municipal lands. Species selection should always avoid

tree species known to be invasive, and include as great a diversity of native or indigenous

species as possible (Town of Ajax, 2011, p.62),” it is unclear from the UFMP what the right

34

number or frequency of native species planting is.

In addition to the absence of specific targets in the UFMPs, municipal planting lists lack native

species diversity, indicating that the stated goals are generally not being operationalized. Every

municipality interviewed had a tree species planting list, including municipalities without

UFMPs. Each planting list featured small, medium, and large stature trees with a variety of

native and non-native trees present. The number of trees on the planting lists ranged from 23 to

86 species (or varieties), while the number of native tree species on these lists ranged from 13 to

47. No list was more than 57% species native to the Carolinian Zone.

The planting lists that have the fewest native species tended to only include the most common

native species found on all lists (Acer saccharum (sugar maple), Acer rubrum (red maple),

Quercus rubra (red oak), Amelanchier (serviceberry), Gleditsia triacanthos (honey locust),

Celtis (hackberry)). The planting lists with higher diversity typically included rare native

species, more southerly species, and less common non-native species. Those municipalities with

an UFMP did have a high percentage of species native to the region on their planting lists

(averaged 49 species; 26 native species) compared to the non-UFMP municipalities whose lists

were examined (averaged 33 species; 15 species). However, of the more than 80 trees native to

Carolinian Canada, 35 do not appear on any list.

2.4.2 Planting Practice

The number of trees planted annually by the municipalities ranged from 800 to 100,000, while

the number of trees removed annually ranged from 700 to 15,000. The most commonly planted

35

trees were Acer (maple), Quercus (oak), Tilia (linden), Amelanchier (serviceberry), and Gleditsia

triacanthos (honey locust; Table 4).

Table 4 Most commonly planted tree species in Carolinian Canada

Most Commonly Planted Trees Frequency of Response (out of

13) Native Status

Acer (maple) 8 both native and non-native

varieties

Quercus (oak) 5 native

Amelanchier (serviceberry) 4 native

Tilia (linden) 4 non-native

Gleditsia triacanthos (honey

locust) 4 native

Liriodendron tulipifera

(tuliptree) 3 native

Syringa reticulata (japanese

lilac) 3 non-native

Gingko biloba 3 non-native

Celtis (hackberry) 3 native

The most common factor considered when selecting a species to plant was whether or not the

planting site has a utility conflict associated with it (11 of 16 respondents; Figure 2). One urban

forester stated that “utilities play a very big role in our species selection… So, you know

overhead wires. We are very cognizant of every site where there are overhead wires and we try

to offset the trees so they are more compatible with overhead wires.” Urban foresters were also

heavily influenced by how much growing space there is at the planting site (nine of 16

respondents), objectives of planting for street tree diversity (7 of 16 respondents, and the land

use type (five of 16 respondents).

36

Figure 2 – Most common factors considered by municipal foresters when choosing tree species

to plant

Five of nine interviewees indicated that the planting trends had changed in their municipality

since the enactment of the UFMP. Two of the nine respondents stated that the planting and tree

selection processes changed prior to the enactment of the UFMP in anticipation of the document;

while the other two respondents said that the municipality is in the midst of changing their

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planting and tree selection processes. Five of nine respondents feel that the type and number of

different species currently planted is addressing the goals of the UFMP, while four of nine

respondents felt that the municipality’s planting trends were not addressing the goals.

Tree planting authority across municipalities with and without an UFMP was largely held by the

Forestry department (or equivalent) staff members, however three of 16 respondents indicated

that tree planting selection was not centralized within a single department, but rather, several

departments who are responsible for choosing what trees are planted for their respective projects.

Thus, implementing actions to address the UFMP was not solely the responsibility of the urban

forest department, and there was not necessarily sufficient coordination between units to ensure

this occurred. For example, one municipal forester stated: “Part of the challenges that

municipalities have, is that there’s multiple departments, and there’s not only just the forestry

department, there’s also a parks department, there’s also an urban design department, there’s

also an engineering department that all plant trees, and they don’t always talk.”

All municipal interviewees indicated that the trees they plant are acquired from either a nursery

or a contractor who purchases them from a nursery. Typically, the municipality drafts a contract

that includes the number of trees of different varieties and their condition. Some of the

municipalities have strict specifications regarding tree provenance, especially when planting for

restoration programs (e.g. Guelph, Mississauga, Oakville), others request provenance (e.g. Ajax,

Burlington, Cambridge), and some do not specify. The tree contract is put to tender, and local

tree planting contractors and/or nurseries bid on the contract. Nine of 16 participants indicated

that while their municipality requests the tree species that they want to plant, it is not always

possible to acquire those exact species, and frequently the nursery will provide the municipality

38

with a comparable species instead. While some municipal forestry departments stated that they

are in the process of establishing local seed banks from which some or all of their trees will be

acquired, the majority of the trees being planted are of distant or unknown provenance. This

process of acquiring trees represents an added challenge to planting native trees and establishing

local provenance.

Species Selection: Native versus Non-Native Species

Several interview questions specifically focused on attitudes and actions pertaining to the use of

native species for tree planting. In general, municipalities that do not have an UFMP are

planting a lower ratio of native trees or do not track the relative number of natives planted.

Conversely, five of the nine municipalities that have an UFMP plant only native trees in

restoration and naturalized areas, and eight of the municipalities with an UFMP indicated a

higher proportion of native trees planted overall. The sole exception was Toronto, which has the

highest urban density in the study, where only about 40% of the street trees planted are native

species.

There was little similarity among responses about why native species are preferred or why their

use should be increased (Table 5), however, a general theme of ecological integrity exists

throughout the responses from the municipalities with an UFMP. Respondents indicated their

municipality plants native trees because the Carolinian forest is unique and should be preserved,

it creates a natural seed source, native species are less invasive, they have greater wildlife

benefits, natives fare better, and because natives are needed to increase diversity. Additionally,

four of the nine representatives from municipalities with an UFMP said native trees are planted

39

because the UFMP states that they should be planted, although additional reasons were also

given by these participants. In contrast, six of the seven responses from the municipalities that

lack an UFMP said that native species are not preferred, and their use need not be increased.

Table 5 Reasons given as to why the use of native species should be increased in municipal

plantings

Reasons Why the Use of Native Species Should be

Increased

Carolinian forest is unique

They benefit wildlife

Less invasive

City council requests it

Ecological integrity

Most appropriate for site

They fair better

Sense of place

Easier to grow successfully

It is not a goal (municipalities without an UFMP)

Many species of native trees are not planted by municipalities in Carolinian Canada, for a variety

of reasons. Fraxinus (ash) trees were the most commonly avoided native trees to plant (13 of 16

respondents) because of the Agrilus planipennis (emerald ash-borer) infestation. Nine of 16

respondents indicated that they do not plant conifers and nut-bearing trees as street trees or near

roadways due to potential risks. Additionally, Platanus occidentalis (sycamores; allergen),

Ulmus (elms; Dutch elm disease vulnerability), Acer negundo (Manitoba maple; invasiveness),

and Populus (poplar) and Salix (willow; weak wood) are avoided in many of the municipalities.

Finally, a number of native species are unavailable from nurseries. Interestingly, five of the

40

study municipalities have begun species suitability trials to identify additional native species that

are suitable for use, with the municipal representatives acknowledging many native species are

avoided because it is unknown how they will fare in the urban environment.

In some situations, non-native tree species are selected in favour of native tree species by

municipal foresters. Nearly every reason was related to poor site conditions: All 16 respondents

directly referred to poor site conditions, while other factors that imply poor site conditions (salt

tolerance, compacted soil, wind resistance, utility conflicts, lack of growing space) were also

given as reasons for a non-native tree species selected in favour of a native species (Figure 3).

Figure 3 – Reasons why non-native tree species are selected in favour of native species

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2.4.3 Ecological Integrity and Assisted Migration in Practice

After being provided with the study’s definition of ecological integrity, interviewees were asked

if and how this idea factors into the municipality’s tree planting program. There was a distinct

dichotomy of responses between municipalities with and without an UFMP, as eight of the nine

municipalities that have an UFMP responded that ecological integrity factors into the

municipality’s tree planting program, while five of the seven municipalities that lack an UFMP

indicated that ecological integrity is not a factor. The most common response to how ecological

integrity is included in practice was that the municipality requests that the trees they acquire be

from the local area (five out of 16 respondents), while three respondents indicated that they

require the trees to be from local certified seed sources. Ecological integrity was also identified

as being practiced through planting a higher diversity of trees (two of 16 respondents), planting

more Carolinian and native trees (two of 16 respondents), and practicing habitat restoration (two

of 16 respondents).

We also asked respondents to indicate if and how their municipality practices assisted migration

based on the provided definition. Four of the 16 respondents indicated that they actively (i.e.

purposely) practice assisted migration through their municipal planting decisions, while 10 of 16

respondents indicated that they passively (i.e. unintentionally) practice assisted migration based

on the provided definition. One respondent indicated that they will consider assisted migration

in the future, implying that the term was new to them and that their municipality does not

actively practice assisted migration. Finally, two respondents indicated that they do not engage

in active or passive assisted migration. However, their municipal planting lists certainly contain

42

many non-native species, including those native to regions just south of Ontario, and their other

interview responses indicate these non-native trees are regularly planted.

Assisted migration was most commonly practiced by planting species that are native to a more

southerly range but still coevolved with many of the tree species in Carolinian Canada (i.e.

species from the eastern United States; 12 of 16 respondents), while assisted migration is also

practiced by planting southerly exotic species that will grow in southern Ontario’s climate. All

representatives from municipalities that actively practice assisted migration (four respondents)

do so to prepare for climate change. For example, one respondent stated, “we often choose

species from more southern climates because we know that our climate’s changing, and we are

always looking for species that grow in a more southerly climate, and we try them here in the

city to see how well they will grow, so some of those species will do well or may do very well in

this climate and in some of the growing conditions here.” In addition to practicing assisted

migration to purposely adapt to climate change, it is also practiced by some municipalities

simply because the more southerly tree species will survive and grow (three respondents), as

well as to increase the diversity of tree species in the municipality (one respondent).

2.5 Discussion and Conclusion

This study highlights the attitudes and actions of municipal urban forestry staff towards native

tree species in relation to the goals established in Carolinian Canada’s UFMPs. Municipalities

with an UFMP are emphasizing native species in planning and practice more than those

municipalities without an UFMP, typically justified as a way to increase ecological integrity.

Still, all but two municipal tree planting lists consist of a majority of non-native tree species and

many native species are not planted by any municipality in the study. Thus, a fraction of the tree

43

diversity naturally found in the Carolinian Zone of Canada is planted. Aligning the development

of planting lists with UFMPs stated goals could be a way to more easily achieve these stated

goals, at least among municipalities who have not yet adopted management plans. Most

municipalities are also passively practicing assisted migration, which is not aligned with the

UFMPs’ native emphasis, but many are not exploring the ways assisted migration can be used as

a tool to adapt to climate change.

Municipalities with an UFMP are considering more of the managerial aspects associated with

native species, which is consistent with Ordonez and Duinker’s (2013) review of UFMPs across

Canada. In addition to planning goals, the UFMP municipalities are drawing on more native tree

species than municipalities without an UFMP and planting more native tree species overall. In

contrast, municipalities that lack an UFMP are not prioritizing planting or management of native

trees, and ecological integrity is not considered when making street tree species selection

decisions. In this regard, the existence of an UFMP in a municipality indicates that some of the

higher-level goals surrounding native species have been successfully communicated to and

implemented by the forestry staff.

However, there is no discussion of targets for native ratios or the number of different native

species that should be planted. This is not surprising, given a lack of consistent guidelines from

the urban forestry literature or clear evidence from urban forestry practice. The review of the

municipal tree planting lists highlight that even in absence of clear targets, there is still a

disconnect between the stated preference for planting native trees in the UFMPs and the small

proportion of native tree species actually planted. Additionally, interviewees focused on a few

versatile native species that they knew were easy to grow, indicating that there is a preference for

44

planting the small number of native species that can grow in a variety of conditions, rather than

planting to achieve high native richness.

Research is needed to understand if and to what extent preserving native diversity is important in

achieving ecosystem service provision and other goals unrelated to ecological integrity, and

conversely, the functions and benefits that the novel assemblage of primarily non-native species

provides should be better communicated. However, if a municipality chooses to use native tree

species planting to achieve ecological integrity, they should be clear that it will require planting

less common native species to ensure high native richness, so that municipalities are not creating

a non-diverse, but native urban forest, as this would lead to diminished ecological integrity and

resilience. To support this, more native species suitability trials must occur to determine these

species tolerance to common urban tree stressors. While several interviewees commented on the

high cost of species suitability trials, others suggested coordinating and sharing this research

amongst all Carolinian Zone municipalities through existing forestry councils to ease the cost

burden.

Another challenge associated with operationalizing ecological integrity through native species

planting is the limited availability of native species and difficulty of establishing the provenance

of the trees acquired. In Carolinian Canada, tree nurseries are often not able to meet the requests

of municipalities, limiting the species that can be planted. This is consistent with the findings of

Sydnor et al. (2010), who examined municipal urban foresters’ planting needs in relation to

nursery supply and identified a mismatch between species urban foresters want and those

available from suppliers. While nurseries said they respond to demand, the need to substitute

species due to lack of availability was not necessarily recorded, masking the unmet demand in

45

many cases. In a related study examining wholesale nurseries in Washington State, there was

general support for increasing the diversity of tree species available, but many nursery

representatives surveyed did not know why higher species diversity was important (Polakowski

et al., 2011). The limited availability of native trees in retail and wholesale nurseries, as well as

the aesthetic and economic considerations that dominate their supply decisions, has received

recent attention (Kenney et al., 2011; Pincetl et al., 2013; Conway and Vander Vecht, 2015) and

represents an added challenge to planting native trees and establishing local provenance.

Finally, assisted migration of tree species to ameliorate the anticipated effects of climate change

provides another wrinkle in the decision to manage for high native diversity. While assisted

migration can potentially be used to build an urban forest that will thrive in future climates, as

well as for species restoration, economic gain and/or ecosystem benefits, the risks of introducing

invasive species, failure of plantings that may not be able to survive local conditions or climate

conditions over the short-term, and loss of time and money on failing species need to be taken

into account.

Although a minority of municipalities indicated that they are actively practicing assisted

migration, the majority of Carolinian Zone municipalities in this study are passively practicing it.

In particular, they are planting species from a more southerly zone because they are available and

will grow. Given that there are several risks associated with assisted migration, if municipalities

are practicing it then their actions should be managed thoughtfully by actively choosing which

species to translocate and monitoring their progress, rather than the more passive version that

currently dominates in the region. Keeping in mind that municipalities are bound by strict

financial and temporal budgets, this may best be achieved by partnering with colleges and

46

universities in the region to provide species suitability trial research and development.

Additionally, creating a municipal network that communicates the successes and failures of

planting experimental species under various growing conditions in Carolinian Canada would

eliminate the time and monetary cost of each municipality independently conducting these trials,

and as such, would be an efficient tool for operationalizing assisted migration across the region.

By doing so, municipalities could adaptively manage their urban forest, while also striving to

mitigate the effects of climate change.

While the goals of Carolinian Canada’s UFMPs clearly emphasize native species as a way to

protect and improve ecological integrity, there are an absence of specific targets, due to a lack of

knowledge about many native tree species’ tolerances to urban stressors and no consideration of

the ways other UFMP goals, like ecosystem service provision, may be met with non-native

species. Similarly, though the municipal representatives were generally supportive of native tree

planting, there are many planting scenarios in which non-native species are preferred and

typically more non-native species to choose from, based on official planting lists. Thus, practice

is not fully supporting native species goals. While careful consideration of actively practicing

assisted migration and/or planting non-native species for other reasons would benefit many

municipalities, those that do want to plant primarily native species must address issues of supply

and species suitability to ensure a diversity of native species are represented.

47

Chapter 3

Residential Knowledge of Native Tree Species: A Case Study

of Residents in Four Southern Ontario Municipalities

3.1 Introduction

In our urbanizing world, with finite natural resources that are ever more in demand, urban forests

are increasingly important areas for producing life sustaining ecosystem services and

maintaining ecosystem processes (Collins et al., 2000; Grimm et al., 2013; UNPD, 2010; Wu,

2014). Municipalities throughout North America are adopting strategic plans to manage the

urban forest based on the numerous ecological, social, health and economic benefits ascribed to

them, including storm water retention, filtration of air, shading, urban heat island mitigation,

habitat provision, retention of biodiversity, aesthetic appeal, and food production (Alvey, 2006;

Bolund and Hunhammar, 1999; Nowak and Dwyer, 2007). Recent research has explored how to

sustainably manage urban forests (Clark et al., 1997; Kenney et al., 2011; Mincey et al., 2013;

van Wassenaer and Kenney, 2000; Vlek and Steg, 2007; Young, 2013), with most authors

agreeing that protection of native species is an important component (Alvey, 2006; Clark et al.,

1997; McKinney, 2002; Ordóñez and Duinker, 2012).

Urban forests typically have relatively high species richness, as compared to the surrounding

countryside (Alvey, 2006; Bertin et al., 2005; Miller and Hobbs, 2002; Stewart et al., 2004).

However, this richness is often the result of numerous non-native species being planted, while

many native tree species are absent (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and

Rose, 2000; Schaeplfer et al., 2012). The value of maintaining native species within urban

forests is debated (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff,

48

2005). Goals of ecological integrity suggest that native species should be prioritized (Alvey,

2006; Raupp et al., 2006), but the unique stressors of urban ecosystems, potential ecosystem

services provided by non-native species, and on-going climate change raise questions about the

benefits of a native-only approach (D’Antonio and Meyerson, 2002; Davis, 2012; Hewitt et al.,

2011). While this debate occurs, many municipalities are adopting native-only or native-first

planting goals. For example, Ordóñez and Duinker (2013) found that the one commonality

among all of the existing Canadian urban forest management plans was an objective of

increasing native species.

Recent research has also begun to examine the role of key actors involved with tree planting and

species selection, including NGOs, community groups, and residents (e.g. Avolio, 2015; Conway

et al., 2011; Watkins et al., 2016). Residential support for urban forestry initiatives is crucial,

since the majority of urban trees are planted on residential property (McPherson, 1998; Nowak,

2012), though there is little understanding of how to activate residential support for municipal

urban forest goals. Additionally, while municipalities are depending on residents to be urban

forest partners, it is unclear what residents’ knowledge-level is regarding common species and

key management goals, or if identifying residents as partners in urban forest plans has actually

increased knowledge (through education programs and other outreach).

Studies suggest that knowledge of species, along with an interest in and experiences with nature,

are the factors that best promote an understanding of environmental issues, biodiversity and

sustainable lifestyle (Chawla, 1999; Corcoran, 1999; Lindemann-Matthies, 2006; Martin, Sorice,

and Kreuter, 2013; Palmberg and Kuru, 2000; Palmberg et al., 2015; Palmer et al., 1999). Thus,

assessing residents’ current knowledge about urban forests is important to provide a better

49

understanding of residents’ decisions related to urban forest management, as well as to assess if

they have the basic knowledge necessary to be good partners with their municipality on urban

forest initiatives.

The goals of this study are to determine if: 1) residents in municipalities with an UFMP are more

knowledgeable about the native status of common street trees; 2) residents who have lived in the

area longer have greater knowledge; 3) knowledge level is correlated with education level,

ethnicity, or income; and 4) residents’ knowledge is related to having planted trees on their

property. These goals are addressed through a case study of four urban municipalities in

Carolinian Canada (Ontario, Canada), a region with relatively high native species richness.

3.2 Residents and the Urban Forest

The role of residents in shaping the urban forest is far less clear than that of the municipality.

This is largely because residents’ greenery choices on their own property go widely

undocumented. There are typically no legally enforceable mandates for residents to plant

specific species of trees, much less any trees, on their property (with the exception of

replacement trees when removing existing trees in some cases; Conway and Urbani, 2007) and

residents have varied decision-making processes related to residential landscaping (Kirkpatrick

et al., 2012). However, residents collectively are perhaps the most important actor regarding

urban forest composition and health as approximately 75% of all urban trees are located on

private property and 75% of those are estimated to have been planted by residents (Nowak,

2012). This means that in order to effectively manage the urban forest, policy and practitioners

must influence the actions and perceptions of residents through various forms of engagement,

including education.

50

Not surprisingly, knowledge of urban trees appears to be related to attitudes and actions towards

the urban forest, including tree planting decisions. Generally, people who are knowledgeable

about urban tree programs and forestry services are more likely to donate money and support the

goals of tree planting programs (Zhang and Zheng, 2011). Additionally, positive attitudes

towards urban biodiversity, native species, and a general concern for the environment are

correlated with knowledge of common native species (Kurz and Baudains, 2012). This is

important because if residents’ actions are guided by their knowledge and attitudes, then

educating residents about municipal urban forestry plans should help achieve the long-term goals

laid out in those plans.

Kirkpatrick et al. (2012) examined residents’ tree planting motives in eastern Australian cities

and found a positive correlation between people’s willingness to plant native trees and their

knowledge of common tree species. Kaplan and Herbert (1987) measured landscape preferences

amongst students from Western Australia and Michigan, as well as from a group of

conservationists in Western Australia, and found that landscape preferences differed more

between the conservationists and the Western Australian students than they did between the

Western Australian and Michigan students. They ultimately concluded that species knowledge-

levels have an effect on preference.

While studies researching residents’ native tree species knowledge have been conducted in

Australia, where the threat of exotic-invasive species is highly publicized due to their unique

species assemblages and the influence of global trade (Kirkpatrick et al., 2012; Kurz and

Baudains, 2012), and in Arizona, where the arid climate inhibits many would be invaders

(Larson et al., 2010), residents’ knowledge of native species and urban forestry issues in the

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North American temperate forest has been largely unstudied. Similarly, there are few published

studies that examine knowledge of common tree species, though it is clear that a variety of

factors can influence knowledge-levels associated with the environment, and urban forestry more

specifically.

Not surprisingly, exposure to environmental information and specific knowledge sources leads to

greater understandings of the environment. Martin et al. (2013) found that environmental

education of residents increased their knowledge of all environmental knowledge domains, while

Arbuthnot (1977) concluded that environmental knowledge was directly correlated with having

been exposed to detailed sources of information about it. Similarly, students gained a modest

increase in overall knowledge of environmental issues when exposed to environmental programs

(Armstrong and Impara, 1991). More specifically, Luckmann (2014) noted that educational

programs motivate and evoke an interest in students regarding knowledge of species. Other

studies link knowledge and awareness of environmental issues to attitudes and ultimately support

for specific policy initiatives (Slimak and Dietz, 2006; Zahran et al., 2006). Thus, municipalities

with goals of residential engagement and action should be exposing residents to information that

would increase their ability to identify common trees.

Others have focused on sense of place, local knowledge acquisition, and childhood experiences

being related to knowledge about the local environment. Several studies have emphasized a

sense of place as being an important driver of local action and planning initiatives, which may

become operationalized through knowledge of place (Davenport and Anderson, 2005; Gobster et

al., 2007; Larson et al., 2009; Romig, 2010; Williams and Stewart, 1998). For example, a

resident survey in Austin, Texas found a strong correlation between local newspaper readership

52

and knowledge of the city’s wildland management program (Martin et al., 2013). Formal and

informal childhood education also provides a venue to gain knowledge about local environments.

Lohr and Pearson-Mims (2005) found that children’s interactions with plants influence their

knowledge and attitudes towards trees and gardening as adults, while Olive (2014) indicated that

residents’ knowledge of endangered species in Canada would benefit from eco-literacy school

programs, based on the success of these programs to inform pupils. Thus, location of residency

during childhood, or length of residency in a place, may influence knowledge about local tree

species.

On the other hand, residents’ interactions with common tree species likely reflects social,

demographic, or cultural factors like income, education-level, and ethnicity (Cilliers et al., 2012;

Kendal et al., 2012; Marco et al., 2010), which may affect their knowledge of the native status of

common tree species. Past studies have shown that low-income populations lack access to urban

greenery and high-levels of canopy cover (Grove et al., 2014; Landry and Chakraborty, 2009;

Pham et al., 2012). Whereas other studies have found that education-level, rather than income, is

a better predictor of vegetation characteristics in urban areas (Heynen and Lindsey, 2003, Luck

et al., 2009). This relationship has been attributed to greater knowledge about the benefits of

vegetation (Luck et al., 2009) or a higher value placed on vegetation by the more educated (Lohr

et al., 2004). Additionally, several studies correlate ethnicity with uneven distributions of urban

trees, as well as interest level in urban forestry activities (Heynen et al., 2006; Perkins et al.,

2006; Perkins and Heynen, 2004; Zhang and Zheng, 2011), likely due to cultural preferences

(Fraser and Kenney, 2000). As a result of these relationships, people from varied socio-

demographic groups may have different knowledge-levels about common species.

53

Finally, knowledge of the native status of common trees may also be accrued via hands-on

experiences. Sommer et al. (1994) noted that residents involved in tree planting had a greater

sense of ownership and pride in the urban forest. Exposure to traditions of gardening, tree

planting, and landscaping have also been shown to have an influence on residents’ knowledge of

urban forestry issues (Jones et al., 2013). Summit and Sommer (1998) found that tree-planting

programs can show residents how easy it is to plant trees, demonstrate their benefits, create

opportunity for people to work together, and make environmental values and behaviour more

appealing, which leads to greater knowledge of trees and nurtures environmental protection and

sustainability values. This study explores residents’ species knowledge to better understand

residents’ role in urban forest dynamics and, more specifically, their potential to help

municipalities address native species goals.

3.3 Methods

3.3.1 Study Area

As described in Chapter 1 this study focuses on residents’ knowledge of native tree species in

four municipalities within the Carolinian Zone of Ontario, Canada (Figure 4).

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Figure 4 - Map of the Carolinian forest zone in Canada showing the four surveyed

municipalities

Four municipalities within the Carolinian Zone were chosen as case studies: London, Hamilton,

Oakville, and Markham (Table 6). These municipalities were selected because they are

relatively large cities, two of which are characterized by new urban growth with higher average

incomes and immigrant populations (Markham and Oakville) and two municipalities that are

characterized by older urban growth, lower incomes and smaller immigrant populations

(Hamilton and London). Oakville and London have active UFMPs that emphasize both native

species and resident engagement (City of London, 2012; Town of Oakville, 2008), while

Markham and Hamilton do not. These municipal factors (population, income, immigration,

55

presence of an UFMP) were considered because they are related to the distribution of the urban

forest (Heynen and Lindsey, 2003; Pham et al., 2012), as well as influence basic knowledge of

one’s environment (Williams and Stewart, 1998).

Table 6 Municipal demographics (Statistics Canada, 2011)

Municipality Area

(km2) Population

Population

density

(people/km2)

Median

household

income

Percentage

immigrants

Survey

response

rate (%)

London 421 366,151 871 $73,107 21 44

Hamilton 1,117 519,949 465 $76,742 25 34

Oakville 139 182,520 1,314 $159,724 31 33

Markham 213 301,709 1,417 $108,520 58 29

3.3.2 Resident Surveys

Residents’ knowledge of the native-status of common tree species, municipal urban forestry

goals, and related topics such as their location in the Carolinian Zone, were explored through a

survey. Sixteen hundred residents were sent surveys (400 in each municipality) in the summer of

2015 using a spatially stratified random sample to capture a range of socio-demographics within

each municipality. A multiple contact approach was employed, with up to four attempts at

contacting the residents (Dillman, 2007). Initially, a recruitment postcard was mailed to all

possible participating households, alerting them to the coming survey and letting them know they

had the option to respond online. The survey was mailed a week later, followed by a reminder

56

letter, and then a second copy of the survey, if needed. Informed consent was obtained from all

individual participants included in the survey.

At the start of the survey we defined several terms (Table 7) to ensure a basic knowledge of each

concept and consistent interpretation. The survey contained a list of 12 tree species (6 common

native species, and 6 commonly planted non-native species) that residents were asked to label as

native, non-native, or “do not know”. Common native and commonly planted non-native trees

were chosen based on Waldron (2003) and southern Ontario municipal inventory and planting

lists. Native-status is based on Farrar (1995) and Waldron (2003), with common names used in

the survey. Participants were also asked to indicate if they had ever knowingly planted a native

tree on their property, the total number of trees they have planted on their property, and if they

knew their municipality was located in the Carolinian Forest zone. Basic socio-demographic

data was also collected. Residents from the two municipalities that had enacted an UFMP

(London and Oakville) were asked three additional questions regarding their UFMPs: if they

were aware of their municipality having an UFMP, if they had read any of the UFMP, and did

they believe that the municipality had effectively communicated the goals of the UFMP to

residents. Residents in the municipalities that lack an UFMP (Hamilton and Markham) were

asked if they believe their municipality should enact one.

Table 7 Terms that were defined for the survey respondents for ideological consistency

Term defined on survey Definition provided

Native species

Native species are defined as a species that occurs naturally

within a region, either evolving there or arriving and becoming

established without human assistance.

Tree A tree is a woody perennial plant, having a trunk greater than 10

cm (4 inches) in diameter.

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After the first round of survey mailings, the survey question sections were rearranged to make

the survey more approachable. Specifically, residents were initially asked to identify which trees

are native and then asked property specific questions about their trees. In the revised survey,

these sections were reversed as it was thought that these knowledge testing questions may be less

appealing, and therefore dissuade some from completing the surveys. We found no statistically

significant differences between responses from the original survey and the revised survey, thus,

we do not differentiate these groups in the analysis.

Basic summaries of knowledge-levels and socio-demographics of respondents were calculated,

with survey socio-demographics compared with municipal characteristics. Based on the

literature, we propose four possible hypotheses for why residents may have different levels of

knowledge about species’ native-status. The hypotheses are:

H1: Respondents’ knowledge will be correlated with the presence or absence of an UFMP in

their municipality, based on the plans’ emphasis on native species and resident engagement.

H2: Respondents’ knowledge will be correlated with length of residency (in Ontario; in their

home) associated with local knowledge acquisition.

H3: Respondents’ knowledge will be correlated with education-level, ethnicity, and income

associated with preferences and access to knowledge, trees, and experts.

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H4: Respondents’ knowledge will be correlated with having planted trees on their current

property associated with experiential knowledge.

These hypotheses were tested through a series of cross tabulations using Cramer’s V as the test

statistic. In order to meet the assumptions of Cramer’s V, some categories were combined to

meet the minimum sample requirements. Knowledge-level was represented as a categorical

variable (0-3 correct, 4-6 correct, 7-9 correct, or 10-12 correct) reflecting the number of species a

respondent correctly identified as native or exotic.

3.4 Results

Of the 1600 possible respondents, 90 surveys were not successfully delivered, and 552 surveys

were completed, representing a 37% response rate. London had the highest response rate at

44%, and Markham had the lowest at 29% (Table 6). The average age of the respondents was 58

years, and 55% were male. On average, respondents had lived at their current residence for

between 15 and 19 years and 59% were born in Ontario (Table 8). The average annual

household income was $117 650, with 96% homeownership. At least a university bachelor’s

degree was completed by 45% of survey participants, while 81% of respondents indicated either

a British Isles or European ethnicity.

In comparison to the most recent census data (Statistics Canada, 2011), the percentage of

university-educated participants and average household income was higher for survey

respondents than the corresponding municipal-level (Table 9), possibly as a result of limiting

participants to non-apartment dwellers. With the exception of London, the number of Ontario

born survey participants reflects the proportion of the municipality born in the province.

59

However, the accuracy of the 2011 census is unclear (Statistics Canada, 2015), making the cause

of divergences (census issues, survey representativeness, or temporal differences) uncertain.

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Table 8 Summary of socio-demographic and tree planting variables, shown as percentage of all

respondents

Combined London Hamilton Oakville Markham

Born

Ontario 59 50 67 73 49

Outside of Ontario 41 50 33 27 51

Years at this current address

1 year or less 4 4 5 3 6

2 to 4 years 10 10 12 10 10

5 to 9 years 16 17 17 15 12

10 to 14 years 15 17 8 13 20

15 to 19 years 13 13 13 10 18

20 or more years 42 40 45 49 34

Education

No certificate, diploma or degree 3 2 8 1 3

High school certificate or equivalent 19 23 24 13 12

Apprenticeship, College, CEGEP 30 35 36 20 25

University Bachelor’s degree 33 22 24 49 46

Masters or Doctorate degree 15 19 8 18 15

Household Income

0 to 29 000 5 6 7 5 1

30 000 to 59 000 22 24 30 16 17

60 000 to 89 000 23 21 24 29 18

90 000 to 119 000 16 17 10 23 11

120 000 to 149 000 9 6 16 10 5

150 000 to 179 000 9 12 4 8 11

Over 180 000 16 14 9 10 37

Ethnicity

British Isles 51 64 45 67 19

European 30 30 42 19 26

Other 19 5 13 14 55

Planted a tree on your property

Yes 71 80 62 76 59

No 29 20 38 24 41

Planted a native tree on your property

Yes 36 43 31 38 26

No 64 57 69 62 74

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Table 9 Comparison between survey participant demographics and municipal demographics

(Statistics Canada, 2011)

Survey Respondents, 2015 Statistics Canada, 2011

Municipality At least a

bachelor’s

degree

Born in

Ontario

Median

household

income

At least

bachelor’s

degree

Born in

Ontario

Median

household

income

London 38% 47% $108,450 28% 70% $73,107

Hamilton 30% 67% $104,000 23.5% 68% $76,742

Oakville 62% 51% $145,050 46% 56% $159,724

Markham 56% 30% $119,220 40% 37% $108,520

3.4.1 Knowledge

When asked to indicate the native-status of the 12 tree species, overall knowledge was low

(Table 10), while the correct status was given most frequently for Acer saccharum (native –

82%), Juglans nigra (native – 65%), and Quercus rubra (native – 64%). Respondents were least

likely to know the native-status of Catalpa speciose (exotic – 17%), Tilia cordata (exotic –

20%), and Liriodendron tulipifera (native – 24%; Table 11). Five of the six most correctly

identified trees were native species, while responses for non-native species were more frequently

incorrect or ‘do not know’. Knowledge of the native status of common tree species was highest

amongst London respondents (44%) and lowest for Oakville (35%), although correct

identification of native trees was higher than that for non-native trees across all four

municipalities.

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Table 10 Number and percentage of all survey participants in each category of knowledge of the

native-status of common tree species

Number of Correct Answers to

Native Status of Tree Questions

Number of

Respondents

Percentage of

Respondents

0 93 17%

1 to 3 117 21%

4 to 6 175 32%

7 to 9 118 21%

10 to 12 50 9%

Table 11 Percentage of respondents who correctly identified tree species (* denotes native

species)

Combined London Hamilton Oakville Markham

Acer saccharum* 82 89 88 82 72

Juglans nigra* 65 80 76 57 49

Quercus rubra* 64 65 70 66 63

Gingko biloba 46 58 50 36 47

Fraxinus pennsylvanica* 45 49 46 42 47

Platanus occidentalis* 35 41 42 33 27

Acer platanoides 34 40 31 34 36

Cercidiphyllum 33 35 33 28 40

Syringa reticulata 24 25 24 21 33

Liriodendron tulipifera* 24 33 25 19 16

Tilia cordata 20 26 18 15 24

Catalpa speciosa 17 18 17 13 13

With regard to activity and urban forest issues in southern Ontario, 34% of respondents indicated

that they had knowingly planted a native tree on their property, with 71% planting at least one

tree on their property. Twenty-eight percent of respondents were aware that their municipality

lies within the Carolinian Zone of Canada. There were, however, large differences in having

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knowingly planted a native tree between municipalities (26% - 44%), and knowledge of being

located in the Carolinian Zone (10% -47%) that mirrored the pattern of correctly identifying

native-status (Table 12).

Table 12 Percentage of correct responses for native and non-native tree species, as well as other

urban forest topics

Native

correct

Non-

native

correct

Carolinian

awareness

UFMP

awareness

Read

UFMP

UFMP goals

communicated

effectively

London 29% 16% 47% 53% 8% 19%

Hamilton 27% 13% 25% N/A N/A N/A

Oakville 23% 12% 21% 50% 13% 17%

Markham 22% 16% 10% N/A N/A N/A

Fifty-one percent of respondents from the municipalities that have an UFMP were aware that

their municipality has a management plan, but only 10% of respondents said that they had read

any part of it (Table 11). Thirty-four percent of respondents indicated that they did not feel as

though their municipality had meaningfully communicated the goals of the UFMP, while 48% of

respondents were indifferent about goal communication. In the municipalities without an UFMP

only 2% of respondents were not in favour of their municipality drafting one.

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3.4.2 Factors related to knowledge-level

The results of the hypothesis testing are shown in Table 13. Respondents’ knowledge was not

significantly related to the presence or absence of an UFMP in their municipality, providing no

support for the first hypothesis that survey participants in municipalities with an UFMP would be

more knowledgeable. In relation to H2, knowledge-level was positively related to length of

residency at current address (p-value = 0.011), but there was no significant relationship between

knowledge of the native status of common tree species and location of birth in or outside

Ontario.

Table 13 Cross tabulation results based on Cramer’s V, with p-value in parentheses. See Table 8

for variable categories

Variable

Correctly

identified

species

Carolinian

awareness

UFMP

awareness1 Read UFMP1

UFMP goals

communicated

effectively1

UFMP

adopted 0.052 (0.831) 0.187 (0.001) N/A N/A N/A

Place of birth 0.096 (0.590) 0.138 (0.757) 0.079 (0.573) 0.063 (0.637) 0.105 (0.583)

Length of

residency 0.244 (0.011) 0.16 (0.523) 0.123 (0.410) 0.150 (0.096) 0.213 (0.594)

Education 0.143 (0.596) 0.363 (0.007) 0.207 (0.016) 0.194 (0.167) 0.289 (0.018)

Income 0.176 (0.829) 0.172 (0.113) 0.13 (0.156) 0.174 (0.683) 0.285 (0.578)

Ethnicity 0.125 (0.291) 0.335 (0.001) 0.366 (0.039) 0.339 (0.836) 0.382 (0.227)

Planted a tree 0.232 (0.034) 0.144 (0.222) 0.207 (0.054) 0.214 (0.200) 0.234 (0.104)

Planted a

native tree 0.311 (0.001) 0.087 (0.380) 0.128 (0.062) 0.150 (0.140) 0.197 (0.018)

1 These cross-tabulations were only completed for respondents in the two municipalities with an

UFMP (London and Oakville).

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Education-level, income, and ethnicity (H3) were not significantly related to knowledge of the

native status of common tree species. However, socio-demographics were significantly related to

other urban forest topics. Respondents with higher education levels were more likely to know

that their municipality had an UFMP (p-value = 0.016) and that they lived in the Carolinian zone

(p-value = 0.007). However, the higher the level of education of the respondent, the more likely

they felt that the goals of the UFMP had not been effectively communicated (p-value =0.018).

Ethnicity also played a role in general knowledge, as 56% of respondents who indicated a British

Isles or European ethnicity were aware of their municipality having an UFMP, but only 27% of

other ethnicities were aware of their municipality having an UFMP (p-value = 0.039). Thirty-

seven percent of respondents who identified as British and 29% of respondents who are

ethnically European were aware that their municipality lies in the Carolinian Zone, while only

5% of respondents who indicated another ethnicity knew they lived in the Carolinian Zone (p-

value = 0.001). Income showed no significant relationship to knowledge of native species,

municipal policy, or Carolinian Canada.

Finally, native species knowledge-level was significantly related to having planted trees on one’s

current property (H4), as respondents correctly identified more tree species’ status the higher the

number of trees they had planted (p-value = 0.034). Similarly, having planted a native tree on

your property also increased the likelihood of being knowledgeable about the trees’ native status:

of those participants who correctly identified at least nine of the 12 species, 56% had knowingly

planted a native tree, as compared to 34% of all participants (p-value = 0.001).

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3.5 Discussion

This study explores residents’ knowledge of common tree species and urban forestry issues in

southern Ontario municipalities. Overall, native tree species in the urban forest are more

identifiable by residents than common non-native tree species, but knowledge-levels are

generally low: only three of the 12 common species could be correctly identified by more than

half of the participants. Other studies have similarly found that residents’ knowledge of native

species is lacking (Brzuszek et al., 2007; Meyer, 2005), and that there is a general societal

knowledge deficiency regarding local ecology (Arbuthnot, 1977; Armstrong and Impara, 1991;

Brzuszck et al., 2007; Carrier, 2009; Chipeniuk, 1995; Corcoran, 1999; Lindemann-Matthies,

2006; Luckmann and Menzel, 2014).

The results from the survey indicate that respondents did not avail themselves of digital or print

information when they filled out the survey, skewing the number of species they correctly

identified, as less than two percent (10 of 552) of respondents correctly answered all 12

knowledge questions. It was communicated to the survey respondents that the data being

collected was exploratory, there was no incentive to have a higher knowledge score, and

individual results would not be published. While “cheating” about tree knowledge was an option

for respondents, it seems that if any cheating occurred it was minimal.

Hypothesis 1, that respondents’ knowledge would be correlated with the presence or absence of

an UFMP in their municipality, is rejected based on the survey responses. This may be related to

the short period of time that the UFMPs have been in place (Oakville, 2008; London, 2012). But

the poor communication of the plans’ goals, as expressed by many survey participants, suggests

that little education has occurred. Resident engagement in the region is often limited to

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encouraging residents to help meet tree planting targets, such as London’s Million Tree

Challenge (http://www.reforestlondon.ca/), or allowing homeowners requesting a city-tree in

front of their house to choose from a short list of site-appropriate tree species (Almas and

Conway, 2016). Furthermore, the much higher knowledge of one’s municipality having an

UFMP and living in the Carolinian Zone among participants with British or European

background as compared to participants who identify as other ethnicities, who are typically more

recent immigrants to Canada, suggests that engagement is uneven among different ethnic

communities in the study area.

The limited and uneven awareness that is reflected by study participants illustrates a broader

issue of uncertainty about how to engage with residents, particularly those who are not already

interested in urban forestry issues. Summit and Sommer (1998) outlined basic steps for public

engagement in urban forestry programs, including making the desired behavior easy and clearly

communicating the threat and ways that residents can help address it. While the study area

municipalities and other cities are taking some of these steps in tree planting programs,

communicating the importance of native species, when there is still debate about their value

(D’Antonio and Meyerson, 2002; Davis, 2012; Kendle and Rose, 2000; Sagoff, 2005; Schaeplfer

et al., 2012) and many instances where municipalities are choosing to plant non-native trees

(Almas and Conway, 2016), requires messaging that is not as simple as ‘plant more trees’.

Moreover, Johnston and Shimada (2004) argue that terms like ‘native’ and ‘alien’ can be

offensive, discouraging further interest among immigrant populations. Thus, cities like Oakville

and Markham, with sizable immigrant populations, may face additional challenges about how to

communicate information in a way that will be inclusive. Alternatively, a strategy to engage

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newcomers and residents of minority ethnic groups is to highlight the multicultural nature of the

urban forest itself, as common urban species originate from many parts of the world (Johnston

and Shimada, 2004). However, this is at odds with management goals that emphasize native

trees.

Residents’ length of residency was related to correctly identifying the native-status of tree

species (H2). Similarly, the longer residents lived in their house, the more likely they were to

have read some of the UFMP, which is in line with previous findings that people who have lived

in a community for a long period of time tend to be more knowledgeable about and engage in

their community’s activities (Romig, 2010; Williams and Stewart, 1998). An explanation for

this is that the longer a person has lived at their current location the more likely they are to have

had reasons to interact with the native ecology (Martin et al., 2013), whether by reading the

newspaper, engaging in community activities, social media, or physically walking amongst it.

The role of residential length in relation to knowledge about a place suggests that increasing use

of traditional and social-media may help educate residents about native tree species.

Furthermore, Lindgren (2015) argues that social media can be effective in reaching new

residents, who we found to be less knowledgeable about native tree species. However, a survey

of 463 municipalities across the United States indicates that social media communications are

under-utilized by municipal governments (Graham and Avery, 2013), suggesting its potential of

is not being fulfilled.

Somewhat surprisingly, there was no statistically significant relationship between correctly

identifying tree species and being born in Ontario, perhaps because there has not been exposure

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to native trees through formal or informal childhood education. This is at odds with other studies

that suggest being born and educated in your place of residence is a good predictor of knowledge

of flora and fauna (Corcoran, 1999; Olive, 2014; Palmer et al., 1999). However, Palmberg et al.

(2015) found that students are not exposed to native species in their local environment, and argue

that experiential methods should be mandatory for learning about native ecology.

The lack of formal education about native tree species was further highlighted through the

rejection of H3, that respondents’ knowledge would be correlated with education-level, income,

and ethnicity. However, we did find that those with higher levels of education were more likely

to know that their municipality is located in Carolinian Canada and that their municipality has an

UFMP, suggesting that acquisition of knowledge about native tree species is different and

perhaps less easily obtained.

In an attempt to increase knowledge of local environments, several schools across the globe

(including in Ontario) have created an outdoor-based curriculum. These ‘forest schools’

acknowledge society’s lack of connection with the natural world and base their curricula on

nature immersion as the primary form of education (Forest School Canada, 2014). Since

municipalities have prioritized the use of native species in UFMPs, residents require some basic

knowledge of native ecology if they are to be helpful urban forest partners. Though entire school

curricula devoted to outdoor education may not be necessary to fulfill basic knowledge criteria,

primary school programs that introduce students to common urban tree species using a variety of

learning methods would likely help prepare children to be good partners in municipal urban

forestry initiatives.

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Finally, Hypothesis 4, that respondents’ knowledge is correlated with having planted trees on

their current property, was supported by the survey results. However, it is unclear whether

residents who have planted a tree were more knowledgeable about trees’ native-status before

planting their tree(s), or if the experience provided the learning opportunity. As several studies

suggest that experiential learning is linked to strong memory retention (Carrier, 2009; Dunphy

and Spellman, 2009; Kolb, 1984), it is possible that information gained from researching what

type of tree to plant would be retained. On the other hand, those with prior knowledge of tree

species native-status may have a proclivity towards trees that would result in them being more

likely to plant tree(s).

This study explores a particular aspect of native tree knowledge: ability to identify locally native

and non-native tree species based on their common name. We did not examine if this type of

knowledge is related to being able to physically identify species in one’s local environment or

understanding the role native species play in ecological integrity. However, we chose to focus

on this aspect of native species knowledge because residents who decide to plant a tree are

typically buying them from nurseries (Conway, 2016), but many nurseries are not interested in or

knowledgeable about native tree diversity (Brzuszck et al., 2007; Sydnor et al., 2010;

Polakowski et al., 2011; Conway and Vander Vecht, 2015). Thus, the ability of residents to ask

for native trees by name may be equally or more important than being able to physically identify

species when the objective is having residents’ planting species that will support municipalities’

native species objectives.

Undoubtedly, urban forestry programs have the potential to determine the forest structure and

species diversity in a municipality (Summit and Sommer, 1998), but additional public education

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needs to provide basic knowledge in order for residents to have the tools needed to support

municipal management goals. Since all Carolinian Zone UFMPs emphasize the planting and

maintenance of native tree species over non-native species (Almas and Conway, 2016), assessing

residents’ knowledge of native species is crucial to establish a baseline for understanding how

much community education needs to occur in order to have residents function as knowledgeable

tree planting partners. This study indicated a lack of effective education in the two

municipalities with UFMPs, and the particular need to reach newer residents and those who have

not previously planted trees. To this end, there are opportunities to include native species in

school curricula, as well as provide learning opportunities for all residents. However, remaining

challenges include communicating native species objectives in an inclusive way that will

encourage supportive actions by all residents and reaching new residents to facilitate their

knowledge acquisition about the local environment.

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Chapter 4

Resident Attitudes and Actions Towards Native Tree Species:

A Case Study of Residents in Four Southern Ontario

Municipalities

4.1 Introduction

As more of the world’s finite land area is used for urban development and agriculture, urban

forests are increasingly becoming important areas for producing life sustaining ecosystem

services (Dobbs et al., 2011; Mincey et al., 2013). As a result, urban forests are now often

managed to maximize societal benefits through a focus on ecosystem service provision,

including microclimate regulation, stormwater mitigation, erosion control, shading, carbon

sequestration, and human stress reduction (Alvey, 2006; Bolund and Hunhammar, 1999; Dobbs

et al., 2011). In addition, maintaining natural species assemblages can increase ecological

integrity and provide resilience against disturbances (Alvey, 2006; Alberti, 2010; Ordóñez and

Duinker, 2012; Raupp et al., 2006).

Recent research has focused on the role of key actors involved with planting and maintaining the

urban forest to better understand the socio-ecological dynamics contributing to urban forest

conditions and support effective management (e.g. Avolio 2015; Conway et al. 2011; Watkins et

al. 2016). Of these actors, residents may be the least understood but perhaps the most important,

as the majority of trees in the urban forest are located on private property (Nowak, 2012). Thus,

many of the decisions regarding urban tree planting, species selection, maintenance and removal

are being made by residents. Yet we know little about residents’ attitudes and actions regarding

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specific urban forest topics or level of support for common municipal urban forest management

goals.

An expansive literature has documented the relationship between residents’ socio-demographic

characteristics and urban forest characteristics at the property and neighbourhood-scale, planting

activities, and general support for municipal urban forestry (Kendal et al., 2012; Fraser and

Kenney, 2000; Grove et al., 2006; Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et

al., 2012; Sommer et al., 1994; Tooke et al., 2010; Troy et al., 2007; Zhang and Zheng, 2011).

Additionally, several studies have shown that residents’ attitudes towards urban greenery are

typically expressed through planting and maintenance actions (Conway and Shakeel, 2014;

Finger, 1994; Fishbein and Ajzin, 2010; Zagorski et al., 2004), though it is unclear if residents

are interested in including native species on their property.

The major objectives of this study are to (1) explore urban residents’ attitudes and actions related

to native tree species; (2) examine if the presence of a municipal urban forest management plan

(UFMP) emphasizing native species is related to those attitudes or actions; (3) determine if

attitudes vary among residents with different socio-demographic characteristics; and (4) explore

if positive attitudes towards native species translates into planting native tree species. These

objectives are addressed through a case study of four municipalities, two with an UFMP

emphasizing native species planting, and two without, in Carolinian Canada (Ontario, Canada).

The following sections outline recent research considering native species in urban forests and

resident interactions with the urban forest, our methods and results, and the broader implications

of the relationships present between residents and native tree species.

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4.2 Native Species and Residential Actors in the Urban Forest

Typically, urban forests contain higher tree species richness than neighboring natural forests,

primarily because of the numerous non-native species regularly planted by municipalities,

residents, and other actors (Alvey, 2006; Bertin et al., 2005; Miller and Hobbs, 2002; Stewart et

al., 2004). This richness is not indicative of an even species distribution, as a few species often

dominate, some native species are not planted, and many native and non-native species are quite

rare within a given city (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and Rose, 2000;

Schaeplfer et al., 2012).

The benefit of maintaining native species diversity within urban forests is contested throughout

the academic literature (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012;

Sagoff, 2005; Sjöman et al., 2016); the multiple stressors within urban ecosystems, potential

ecosystem service benefits of planting non-native species, having a limited catalogue of native

species to fulfill ecosystem services and resilient to harsh urban ecosystems, and the uncertainty

of added environmental stressors from a changing climate raise questions about the benefits of a

native-first approach. In any case, as many municipalities are pursuing aggressive tree planting

goals alongside adoption of native species goals - often in response to loss of natural cover

(Bardekjian, Kenney, and Rosen, 2016), there is a push for all urban forest actors to plant more

native tree species in many North American cities.

Across Canada, the planting and maintenance of native tree species is the only management topic

that every existing municipalities’ UFMP has in common (Ordóñez and Duinker, 2013). The

promotion of native species in these plans is based on their contribution to ecological integrity,

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ability to grow well in the local climate, and the known risks associated with invasive non-native

species (Almas and Conway, 2016). Though many municipalities in Canada and elsewhere are

emphasizing native species planting in their urban forests, it is unclear whether residents are

supportive of these goals or taking actions that help meet them.

Residents’ role in shaping the structure and function of the urban forest is not fully understood,

in part, because residents’ planting choices and motivations typically go undocumented.

Collectively, residents manage much of the distribution and condition of the urban forest through

the cumulative effects of many individual property-level decisions (Conway and Shakeel, 2014).

This is particularly true for municipalities that have adopted ambitious long-term management

plans to grow the urban forest, as residential planting is often explicitly needed to achieve plan

goals (e.g. City of London, 2014; Town of Oakville, 2008). Given the short history and lack of

research regarding the influence of UFMPs, it is unclear if their adoption has altered the

likelihood of residents planting a tree, much less a native tree. North American municipalities

typically do not regulate tree plantings by residents (outside of the initial development process),

or dictate which species of trees to plant. So if municipalities are going to affect the actions of

residents, they must do so through education and outreach that influence residents` attitudes and

ultimately impacts their actions. As a result, it is critical to establish a better understanding of

residential planting attitudes and actions in relation to native species, and the factors that are

related to those attitudes.

Attitude is a complex construct, formed and affected by socioeconomic, cultural and biophysical

interactions (Balram and Dragićević, 2004). Knowledge of species, interest in nature, and nature

experiences are the factors that best promote positive attitudes towards environmental issues,

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biodiversity and sustainable life style (Baur and Haase, 2015; Chawla, 1999; Corcoran, 1999;

Lindemann-Matthies, 2006; Martin, Sorice, and Kreuter, 2013; Palmberg and Kuru, 2000;

Palmberg et al., 2015; Palmer et al., 1999); these likely play a role in residents’ attitudes towards

native species in the urban forest. Residents generally express a positive attitude toward trees

(Barro et al., 1997; Jones et al., 2012; Lohr et al., 2004; Schroeder, Flannigan, and Coles, 2006;

Zhang et al., 2007), although Kirkpatrick et al (2012) documented a variety of attitudes towards

urban trees among residents in Australia. Moreover, desire for specific vegetated land covers

varies among ethno-cultural communities and ‘lifestyle groups’, and is not uniform within

income classes (Fraser and Kenney, 2000; Grove et al., 2006).

Education about urban forestry programs can affect the attitudes and actions of residents, with

people who know more about urban forestry programs (measured by the total number of forestry

services the respondent could name) more likely to support the goals of tree planting programs

by donating money (Zhang and Zheng 2011). However, efforts to increase native species

plantings that focus on consciousness-raising and attitude change are not always effective

(Summit and Sommer, 1998). Thus, residents’ native species attitudes are likely a result of

multiple factors, but may not be easy to modify.

Like attitudes, residents’ tree planting decisions are affected by a variety of factors, including

existence of tree planting policy and programs, the availability of trees from nurseries and garden

centres, preferences of influential gardeners and landscape designers, as well as residents’

attitudes (Conway and Vander Vecht, 2015; Kendal et al., 2012). For example, Kirkpatrick et al.

(2012) found residents’ attitudes about urban forest issues, including invasive species, canopy

cover and biodiversity, can affect planting actions on their property in eastern Australia.

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Additionally, residents’ who appreciate native flora, tend to plant native flora. In a study of

residents in Perth, Australia, the attitudinal variable with the strongest relationship to garden-type

preference was residents’ attitude toward native plants (Kurz and Baudains, 2012). Preferences

were also highly related to prevailing gardening norms in respondents’ local area.

Studies regarding residential urban forest native species attitudes and actions have not been

conducted in the Eastern Deciduous Forest of North America, so it is unclear if residents will

have the same attitudes and related actions towards planting native species that residents in

Australia demonstrated.

Recent North American studies have compared residential characteristics, such as participation

in tree planting programs in relation to tree or canopy abundance (Zhang and Zheng, 2011).

Additionally, there is evidence that tree-planting actions vary among residents based on their

socio-demographic characteristics. Locke and Grove, (2016) found that municipal street tree

requests are most likely to come from relatively highly-treed neighbourhoods. Participants in

backyard tree planting programs are more likely to be white homeowners from neighbourhoods

with high socioeconomic status (Greene et al. 2011; Perkins et al. 2004), while people with

higher income and education-levels between the ages of 30 and 49 are most likely to participate

in general urban forestry activities (Fleming et al., 2006).

While attitudes, knowledge, and sociodemographic characteristics affect residents’ planting

actions and support for urban forestry efforts, it is unclear what residents’ attitudes towards

native species in the Carolinian Canada forest are, and whether or not the presence of an UFMP

and/or positive attitudes are associated with actually planting native trees.

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4.3 Methods

4.3.1 Study Area

This study was conducted in four large municipalities in the part of southern Ontario known as

the Carolinian Zone of Canada (Figures 1 and 4), which is described in detail in Chapter 1.

Residents from the municipalities of London, Hamilton, Oakville, and Markham were surveyed

to better understand attitudes and actions towards native tree species (Table 6). These

municipalities were chosen because they are relatively large urban municipalities that have

experienced two distinct patterns of growth. London and Hamilton are characterized by older

urban development, and have been among Canada’s largest municipalities since the inception of

the Canadian Census in 1871. These older municipalities have similar demographics, with

relatively low average household incomes and smaller immigrant populations than the two newer

study areas of Oakville and Markham. The Cities of Oakville and Markham have both

experienced exponential population growth in the past few decades and are two of the most

ethnically diverse municipalities in North America, primarily because of large immigrant

populations. One older (London) and one newer growth municipality (Oakville) have adopted

UFMPs (City of London, 2012; Town of Oakville, 2008), while Hamilton and Markham have

not, allowing for examination of the impacts of the UFMPs and differing demographics on

residential attitudes and actions regarding native tree species in urban forests.

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4.3.2 Resident Surveys

For this study, we used the same survey employed in the Chapter 3 study in which we surveyed

1600 residents (400 in each municipality) in the summer of 2015 about their attitudes and actions

towards native tree species. For details regarding the survey methods see Section 3.3.2. At the

beginning of the survey we defined “tree” as a woody perennial plant having a trunk greater than

10cm in diameter, and “native species” as occurring naturally within the region, either evolving

there or arriving and becoming established without human assistance, to ensure a basic

knowledge of each concept and consistent interpretation. The survey asked residents to indicate

the factors they would consider when deciding to plant a tree on their property, the current

number of trees present, recent actions related to tree planting and removal, and their knowledge

and actions related to their municipality’s UFMP if applicable. Attitude related to respondents’

level of support for native tree species in urban areas was assessed using a five-point Likert scale

for 16 statements related to the planting and maintenance of native species by individuals and

municipalities (See Appendix A). Additionally, residents’ knowledge of native tree species was

gauged, with knowledge based on the number of common street tree species’ native status the

respondent could correctly identify (Almas and Conway, in press).

4.3.3 Analysis

Basic summaries of each survey question were calculated to understand prevailing attitudes and

actions, current property-level tree conditions, and respondents’ socio-demographics. A

principal component analysis (PCA) was completed to analyze relationships among the 16

statements assessing attitudes towards native species. Given the exploratory nature of this study,

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a PCA was chosen in favour of calculating an index that would reflect the various attitudes of

residents regarding native trees, as PCA explores the discrete differences amongst the attitudinal

variables, which should be known prior to calculating an index of attitudes.

Components with eigenvalues greater than 1 were retained (Kim and Mueller, 1978), and used in

an Analysis of Variance (ANOVA) to examine the relationship between native species attitudes,

and categorical variables representing socio-demographics, presence of an UFMP, and residents’

actions. Bonferroni’s post-hoc test was used to determine significant differences between groups

when a significant relationship existed.

The relationship between planting native species, UFMP presence and sociodemographic

variables was initially examined through a series of cross tabulations using Cramer’s V as the

test statistic. In order to meet the assumptions of Cramer’s V some categories were combined to

meet the minimum sample assumptions.

Binary logistic regression was then used to further examine the factors related to having

knowingly planted a native tree. A stepwise analysis was conducted with all possible explanatory

variables, including attitudinal and knowledge based variables. It was expected that the presence

of an UFMP in a municipality would be correlated with more positive attitudes towards native

species and greater likelihood of planting a native species. It was also expected that residents

with higher household incomes would be more likely to plant native species given that wealthier

areas tend to have larger properties with larger planting areas (Gorman, 2004; Landry and

Chakraborty, 2009; Lohr et al., 2004; Zhang and Zheng, 2011) and residents with more

disposable income have more choices when it comes to planting practices, which in turn can also

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lead to opinions being formed about what constitutes “better practice” (Kirkpatrick et al., 2012).

Finally, we expected higher native species knowledge-levels and positive attitudes towards

native species would be related to actually planting native species.

4.4 Results

Of the 1600 possible respondents, 90 surveys were not successfully delivered, and 552 surveys

were completed, representing a 37% response rate. London had the highest response rate at 44%,

while Markham had the lowest response rate at 29% (Table 14). The demographic results

collected in the survey and their overall representativeness are discussed in detail in Section 3.4.

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Table 14 Summary of socio-demographic and tree planting variables, shown as percentage of

all respondents

Combined London Hamilton Oakville Markham

Education

No certificate, diploma or degree 3 2 8 1 3

High school certificate or equivalent 19 23 24 13 12

Apprenticeship, College, CEGEP 30 35 36 20 25

University Bachelor’s degree 33 22 24 49 46

Masters or Doctorate degree 15 19 8 18 15

Ethnicity

British Isles 51 64 45 67 19

European 30 30 42 19 26

Other 19 5 13 14 55

Born

Ontario 59 50 67 73 49

Outside of Ontario 41 50 33 27 51

Years at this current address

1 year or less 4 4 5 3 6

2 to 4 years 10 10 12 10 10

5 to 9 years 16 17 17 15 12

10 to 14 years 15 17 8 13 20

15 to 19 years 13 13 13 10 18

20 or more years 42 40 45 49 34

Household Income

0 to 29 000 5 6 7 5 1

30 000 to 59 000 22 24 30 16 17

60 000 to 89 000 23 21 24 29 18

90 000 to 119 000 16 17 10 23 11

120 000 to 149 000 9 6 16 10 5

150 000 to 179 000 9 12 4 8 11

Over 180 000 16 14 9 10 37

Planted a tree on your property

Yes 71 80 62 76 59

No 29 20 38 24 41

Planted a native tree on your property

Yes 36 43 31 38 26

No 64 57 69 62 74

Knowledge of native trees (correctly

identified native status)

Yes 40 44 40 35 38

No 60 56 60 65 62

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4.4.1 Native Species Attitudes

In general, respondents believe that native species are more beneficial than non-native species in

urban areas: 85% said that native species are or may be more beneficial, while only 15% did not

believe that native species are more beneficial. Based on coding of an open-ended question, the

most common reasons stated as to why native species are more beneficial are: they grow better,

better suited to climate, better chance of survival, they are resilient, they contribute to the native

ecosystem, they are healthier, and non-native trees can become invasive. In contrast, the most

common reasons given as to why native species are not more beneficial in urban areas were:

urban areas are not native, trees are trees, and variety is helpful to adapt to climate change.

While there was widespread recognition of the value of native species in urban areas, only 20%

of respondents said native status of the tree was a primary consideration when choosing a tree to

plant on their property. The most common factors were: shade provision (58% of respondents),

size and shape of tree species (54% of respondents), suits the aesthetic of their home (48% of

respondents), and maintenance requirements of the tree (36% of respondents).

Most respondents (64%) agreed or strongly agreed that their municipality should be planting

more trees, planting more native trees (65%), and that other homeowners should also plant more

native trees (52%). In contrast, only 9% thought that their municipality should plant more non-

native trees. These results are reinforced by the finding that 73% of respondents believe that

their municipality is responsible for maintaining their natural heritage, with more respondents

from municipalities with an UFMP believing (81%) that it is the responsibility of the

municipality to maintain natural heritage. However, only 19% of respondents thought that all

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varieties of native trees should be planted by municipalities if they could lead to added costs or

hazards, and 57% thought that municipalities should not plant native trees if they require extra

maintenance.

Four components were retained from the PCA (Table 15). Component 1 (general attitudes) was

associated with statements that captured attitude towards native tree species issues, with more

positive values related to preference for selecting native species and considering them beneficial.

The statements associated with municipalities and homeowners not needing to plant more trees

were most highly, positively loaded on component 2 (no tree planting). Component 3 (reduced

hazards and future conditions) is associated with statements about tree hazards and practicing

assisted migration. The fourth component (plant all natives) represents the statement: all

varieties of native trees should be planted by the municipality, even if this leads to greater

hazards and/or maintenance costs. It is interesting that this statement was only weakly

associated with the first component, which is most strongly correlated to all other statements

related to valuing and planting native species; support to plant all species of native trees

regardless of hazards and costs differs from generally appreciating native species and believing

that homeowners and municipalities should plant them.

Based on the ANOVA (Table 16), general attitudes towards native species (Component 1) is

strongly related to education and place of birth. Specifically, respondents with higher education-

levels, and those who still live in their municipality of birth or those born in Ontario are more

likely to have positive native species attitudes. Additionally, place of birth is positively related

to the idea that homeowners and municipalities should be planting more trees (Component 2).

Immigrants were more likely to feel that homeowners and municipalities do not need to plant

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more trees (Component 2), but were also more likely to be in favour of planting all varieties of

native trees (Component 4), even if it leads to greater hazards and maintenance costs. Results

from Component 3 (reduced hazards and future conditions) were not significantly related to

place of birth. Importantly, the ANOVA indicated no significant relationships between the

presence of an UFMP and attitudes towards native tree species.

Knowledge of native tree species had a mixed relationship with being in favor of planting all

natives (Component 4). Those who correctly identified the native status of 1 to 3 (out of 12) tree

species were more likely than those who could not correctly identify any species to support the

planting of all native species, while respondents who were able to correctly identify more than

three native tree species did not strongly support planting all natives. Finally, residents who

were aware that their municipality is located in Carolinian Canada were more likely to have

positive attitudes towards native species (Component 1), and believe that more trees should be

planted by homeowners and the municipality (Component 2).

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Table 15 Principle components analysis of native tree species attitude questions

Components

Statements

General

attitudes

1

No tree

planting

2

Reduce

hazards and

future

conditions

3

Plant all

natives

4

Natives are more beneficial in urban areas 0.65 -0.03 -0.192 -0.123

I do not consider nativeness when

planting -0.476 -0.062 0.418 0.365

I want my neighbours to plant native 0.706 0.088 -0.09 -0.059

Two similar trees: native over non-native 0.697 0.151 0.031 -0.071

I Prefer native 0.751 0.306 -0.01 0.014

I prefer a native street tree 0.792 0.213 0.009 -0.003

City should plant more natives 0.728 -0.057 0.084 0.125

Homeowners should plant more natives 0.766 -0.069 0.032 0.118

City should plant more non-native -0.563 -0.008 0.216 0.319

City doesn’t need to plant more trees -0.352 0.767 0.138 0.034

Homeowners don't need to plant more

trees -0.337 0.788 0.091 0.046

Only plant natives that grow well 0.545 0.273 0.323 0.023

City is responsible for natural heritage 0.587 -0.07 0.287 0.312

Plant all native species 0.21 0.053 -0.237 0.784

Don’t plant native trees that have hazards 0.083 -0.023 0.707 -0.388

Practice assisted migration 0.217 -0.31 0.595 0.154

Initial Eigenvalues 5.236 1.570 1.398 1.179

% of Variance 32.725 9.811 8.739 7.368

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Table 16 Analysis of variance (ANOVA) with PCA components, socio-demographics, and action variables

Component 1 Component 2 Component 3 Component 4

Socio-demographics df F P df F P df F P df F P

Gender 1 2.499 0.115 1 1.211 0.272 1 0.120 0.730 1 0.165 0.685

Education 4 5.795 0.001 4 0.791 0.531 4 1.452 0.216 4 2.461 0.045

Ethnicity 2 1.488 0.227 2 2.113 0.122 2 2.485 0.084 2 2.543 0.080

Where born 3 3.133 0.025 3 3.075 0.027 3 2.542 0.056 3 4.773 0.003

Length of time at current residence 5 0.361 0.875 5 0.580 0.715 5 2.133 0.060 5 0.791 0.557

Own or rent home 1 2.381 0.123 1 0.277 0.559 1 0.366 0.545 1 0.021 0.884

Income 6 0.952 0.458 6 1.841 0.090 6 0.289 0.942 6 1.319 0.247

Number of people over 65 4 0.174 0.951 4 2.183 0.070 4 1.144 0.335 4 0.612 0.654

Number of people 45 to 64 3 0.236 0.871 3 1.269 0.285 3 0.602 0.614 3 1.047 0.371

Number of people 18 to 44 4 2.756 0.028 4 0.975 0.421 4 1.406 0.231 4 0.435 0.784

Number of people under 18 4 0.425 0.790 4 1.734 0.141 4 0.856 0.490 4 2.333 0.055

By municipality 3 1.909 0.127 3 1.108 0.346 3 2.091 0.101 3 0.050 0.985

Presence of UFMP 1 1.053 0.305 1 1.029 0.311 1 0.118 0.731 1 0.111 0.739

Knowledge and action variables

Knowledge of native species 4 1.964 0.099 4 0.313 0.870 4 1.252 0.288 4 2.841 0.024

Carolinian Canada awareness 1 28.327 0.001 1 6.980 0.009 1 0.055 0.814 1 3.785 0.052

Participated in UF activity 2 0.091 0.913 2 0.051 0.951 2 0.844 0.433 2 1.072 0.346

Knowingly planted native 1 2.175 0.141 1 0.084 0.772 1 0.382 0.537 1 0.306 0.581

Trees removed since moving 5 0.609 0.693 5 0.546 0.741 5 1.009 0.412 5 0.338 0.890

Trees planted since moving 4 0.488 0.744 4 1.938 0.103 4 1.162 0.327 4 1.999 0.094

Number of trees on property 4 0.410 0.801 4 0.514 0.725 4 0.137 0.969 4 1.051 0.380

Number of native trees on property 4 1.049 0.381 4 2.598 0.036 4 0.623 0.647 4 1.194 0.313

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4.4.2 Native Species Actions

The vast majority of respondents had planted trees on their property since moving there (72%;

Table 17). Additionally, 34% of respondents had knowingly planted a native tree on their

property, meaning that nearly half of the people who had planted trees had knowingly planted at

least one native species.

Not surprisingly, only 6% of respondents indicated that they had planted a tree with the goals of

an UFMP or forestry department in mind. However, respondents who live in municipalities with

an UFMP (London and Oakville) are more actively engaged in planting native trees, planting and

removing of trees on their property in general, and had more trees currently on their property, as

compared to Hamilton and Markham (Table 17).

Through a series of cross-tabulations (Table 18) the relationship between socio-demographic

variables and native species planting actions was explored. There was no significant relationship

between having a native species and planting with forestry goals in mind. However, having

knowingly planted a native species was related to the presence of an UFMP. Respondents’

immediate plans to plant a tree, and plans to plant a native tree were both related to their income

level, with the middle-income respondents most likely to have planting plans. Similarly, plans to

plant a tree and plant a native tree were also related to respondents’ age, with younger (18-40

year-olds) respondents most likely to have plans to plant a tree and plans to plant a native tree.

Results from the logistic regression (Table 19) indicate that knowingly planting native trees is

related to higher levels of knowledge of native trees, awareness of living in the Carolinian zone,

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and presence of an UFMP, while sociodemographics and attitudes towards native trees were not

included in the model. However, the Nagelkerke R Square value was not high (0.152), meaning

there is considerable variation in the planting variable that is not captured by the explanatory

variables.

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Table 17 Summary of respondents’ tree planting actions

Trees Planted and Removed

Number of trees planted 1 to 4 5 to 10 10+ Total:

Percentage of respondents 43% 17% 12% 72%

Number of trees removed 1 2 3 to 5 Total:

Percentage of respondents 22% 14% 24% 60%

Future Actions

Plans to plant a

tree

Plans to plant

native

May plant a

tree

May plant a native

tree

Percentage of respondents 11% 7% 31% 36%

Table 18 Cross tabulation results of action and socio-demographic variables

Age Category Gender

Highest

education Ethnicity

Where

born

Length of

residence Ownership Income

Presence

of UFMP

Knowingly planted

a native tree

Cramer's V 0.069 0.088 0.118 0.014 0.069 0.044 0.034 0.071 0.129

P-value 0.311 0.051 0.146 0.956 0.497 0.964 0.442 0.926 0.003

Plan to plant a tree Cramer's V 0.100 0.04 0.096 0.058 0.052 0.070 0.030 0.181 0.043

P-value 0.039 0.672 0.317 0.490 0.832 0.890 0.788 0.009 0.611

Plan to plant a

native tree

Cramer's V 0.109 0.034 0.100 0.053 0.051 0.073 0.012 0.188 0.044

P-value 0.018 0.753 0.262 0.593 0.843 0.853 0.966 0.005 0.589 Planted with

forestry goals in

mind

Cramer's V 0.029 0.060 0.053 0.044 0.072 0.069 0.020 0.139 0.039

P-value 0.811 0.174 0.836 0.611 0.441 0.780 0.651 0.255 0.364

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Table 19 Variables retained in the step-wise logistic regression (dependent variable =

knowingly planted a native tree)

Variable B Wald Sig.

No UFMP -0.883 11.924 0.001

Carolinian Aware 0.627 5.284 0.022

Knowledge of Trees 19.602 0.001

Knowledge of Trees (0) -2.559 18.863 0.000

Knowledge of Trees (1-3) -1.293 6.136 0.013

Knowledge of Trees (4-6) -1.370 8.032 0.005

Knowledge of Trees (7-9) -1.140 5.252 0.022

Constant 0.729 2.257 0.133

4.5 Discussion and Implications

This study examines the role of residents’ attitudes and actions towards native tree species in

light of recent urban forestry goals to increase their presence. The survey results highlight the

need for municipalities to more actively engage residents regarding the goals and targets of their

UFMPs, and to reinforce the property-level value of planting native trees and achieve resident

buy-in for these initiatives. Most residents expressed generally positive attitudes towards native

species and were overwhelmingly in favour of their neighbours and the municipality planting

more native trees, and most respondents indicated that if given the choice between two trees with

similar attributes they would choose the native tree. These positive attitudes did not relate to

having native trees on their property or to a desire to plant native species regardless of costs.

Additionally, in the event that the native trees could cause hazards or had higher maintenance

costs, then residents tended not to support them.

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There was a strong relationship between respondent’s level of education and positive attitudes

towards native tree species. This relationship between education-level and participation in urban

forest activities has been noted by others (Conway and Shakeel, 2014; Grove et al., 2006;

Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et al., 2012; Tooke et al., 2010;

Zhang and Zheng, 2011; Zhang et al., 2007). Interestingly, other sociodemographic factors

commonly related to urban forest extent and participation (such as income) were not found to be

significantly related to native species attitudes in this study.

One explanation for the significance of education is that public campaigns in Carolinian Canada

against invasive species like Acer platanoides (Norway maple) and Rhamnus cathartica

(common buckthorn) have swayed opinions in favour of native trees. Similarly, the outreach,

including posted signage in the remnant Carolinian forest areas that praise the existing diversity

of native species, likely also have garnered support for native species. People with a higher

education-level are possibly more likely to have been exposed to this literature and/or understand

the broader implications.

In fact, while residents tend to believe that native species are more beneficial in urban areas, the

motivations that drive their tree planting actions are dominated by pragmatic, property-level

concerns such as the size and shape of the tree, amount of maintenance required, shade

provision, and aesthetic-value placed on the tree. This is mirrored by others’ findings that

homeowner planting is primarily motivated by aesthetics and maintenance requirements of trees

(Avolio et al., 2015; Camacho-Cervantes et al., 2014; Conway, 2016; Summit and McPherson,

1998). This dichotomy between attitudes and actions was also observed in relation to municipal

planting. Only 9% of respondents believe the municipality should plant more non-native trees,

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but surveyed residents did not prioritize native species when given the opportunity to choose the

species of tree that the municipality planted on their boulevard. This also helps explain why the

majority of residents have positive attitudes towards native trees, but do not support planting

certain species that may cause additional hazards or maintenance costs.

This pragmatic relationship residents have with native tree species reinforces others’ findings

that suggest factors such as native tree availability from nurseries and garden centres may play a

significant role in the make-up of the urban forest canopy (Brzuszck et al., 2007; Conway and

Vander Vecht, 2015; Polakowski et al., 2011; Sydnor et al., 2010). Since the majority of urban

residents acquire the trees planted on their property directly or indirectly (through contractor

sourcing) from nurseries and garden centres, their choice of tree is limited to what is in stock

(Sydnor et al., 2010), and considering the specific motivations that drive residents’ tree planting

decisions (ie: shade provision, size, shape, aesthetic), it is likely that a native tree may not be

available that meets the specific planting motivations of the resident. It is also noted that garden

centre and nursery employees are often not advocates of native tree species, and may not be able

to recommend a suitable native tree to meet residents stated requirements (Polakowski et al.,

2011).

Residents born outside of Canada indicated less support for native trees as compared to those

who live in the municipality where they were born. This relates to Almas and Conway’s (in

press) findings that immigrants are less knowledgeable about urban forest issues, while residents

who had lived at their house for over 15 years were more knowledgeable about native tree

species in particular. Johnston and Shimada (2004) argue that municipalities often lack the tools

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to meaningfully communicate with immigrants, and that terms like ‘native’ and ‘alien’ can be

offensive, discouraging further interest among immigrant populations.

Based on this study, UFMPs appear to have had some relationship to residents` planting habits,

such that they are more likely to have knowingly planted a native tree. It is unclear if this is a

result of the UFMP, a result of Oakville and London (who have UFMPs) properties having more

available planting space, or if legacy effects from historic socio-economic conditions have

affected current canopy cover patterns (Boone et al., 2010; Luck et al., 2009).

The presence of an UFMP and the availability of resources it takes to enact a plan indicate that

there is some residential buy-in to managing the urban forest in London and Oakville, though

that has not translated into a deeper appreciation for native tree species. Thus, making a

management plan is not enough to achieve a representative native tree canopy. Since the

majority of residents` actions appear to be guided by pragmatic decision-making that prioritizes

aesthetics and tree functions over nativeness, a systemic approach that involves changing the

species availability at the point of purchase (nurseries and garden centres) to represent a wider

diversity of native trees would likely alter residents` actions in favor of native species diversity,

and the pragmatic benefits of native species. A first step that municipalities can take is to require

more native species diversity and quantity in their tree-planting request for tenders from

nurseries, as municipalities are very large contracts, and this requirement should cause the

supply-side to adjust. In some instances, this type of supply-chain influence has been found to

be more effective than educating residents (Summit and Sommer, 1998). Though residents may

still choose trees based on their aesthetic and functional value, if the available nursery stock

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represents a higher number of native tree species, the ratio of native to non-native trees will

likely increase through residential plantings.

Most residents expressed generally positive attitudes towards native tree species in their yards

and in public spaces. However, if costs and risks were greater with native species, fewer

respondents were supportive of native tree planting. Moreover, having a positive attitude

towards native species did not necessarily translate into action. Given that presence of an UFMP

was not significantly related to native species attitudes, municipalities with native species

planting goals should be doing more education and outreach to ensure that residents do not just

express support for native species, but are willing to prioritize them when making species-

selection decisions. Since knowledge of native trees was related to planting native trees,

educating residents about local ecology is a good place to start. Another way of doing this is to

work with nurseries to ensure a diverse supply of native trees, so that residents can meet their

pragmatic species criteria while also selecting a native species.

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Chapter 5

Summary and Recommendations

5.1 Dissertation Summary

Municipalities are managing urban forests to provide ecosystem services, as well as to maintain

ecological integrity. Native species are prioritized in urban forest management planning in order

to meet both of these goals. The first chapter of this dissertation introduced the context, common

themes, study area, and research objectives of this study. The subsequent chapters examined the

role of native species in urban forest planning, municipal foresters’ actions regarding native

trees, and residents’ knowledge, attitudes, and actions regarding native trees and urban forest

topics. Several study methods were employed, including: interviews with municipal foresters,

coding of responses using NVivo software, examination of primary documents, a survey of

residents in four Carolinian Zone (Ontario, Canada) municipalities, and statistical analysis of

responses using SPSS and Microsoft Excel to complete the primary research in this study.

5.1.1 UFMPs, Municipalities, and the Attitudes and Actions of Municipal

Foresters Regarding Native Tree Species

Chapter 2 describes the methods and results related to municipal foresters interviews, and

UFMPs and municipal tree planting lists to establish the role of native species in recent policy

and the relationship between native species policy and practice. While academic discussions

have debated the importance of native species, it was not clear how these debates influenced

municipal policy rationales or practice. Through the case study of Carolina Canada, it was found

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that municipalities with an UFMP are emphasizing native species in planning and practice, and

considering more of the managerial aspects associated with native trees than those municipalities

without an UFMP. UFMP municipalities are also utilizing more native species than

municipalities without an UFMP and planting more native trees overall. In this regard, the

existence of an UFMP in a municipality indicates that some of the higher-level goals surrounding

native species have been successfully communicated to municipal forestry staff, who have then

implemented them. Still, most municipal tree planting lists consist of a majority of non-native

tree species with many native species not being planted by any municipality in the study. As

such, not all of the tree diversity naturally found in the Carolinian Zone of Canada is planted,

potentially leading to a high native ratio but low species richness.

Review of municipal tree planting lists shows that there is still a disconnect between the stated

preference for planting native trees in the UFMPs, and municipal foresters practice of favouring

a few versatile native species that they can depend on to survive urban stressors, rather than

planting to achieve high native richness.

While the goals of UFMPs clearly emphasize native species as a way to protect and improve

ecological integrity, there are a lack of specific targets and no formal consideration of the ways

other UFMP goals, like ecosystem service provision, may be better met with non-native species.

Similarly, though the municipal foresters generally support native tree planting, non-native

species are preferred in a variety of planting scenarios and there are more non-native species to

choose from, based on official planting lists. Thus, practice is not fully supporting native species

goals.

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5.1.2 Residents’ Level of Knowledge of Native Tree Species and Urban Forest

Issues

Chapter 3 explores residents’ knowledge of the native-status of common street tree species and

urban forestry issues in southern Ontario municipalities, to address a gap in our understanding of

residents’ relationship with urban trees. Residents are central actors in urban forest management,

yet research has only recently begun to focus on their knowledge, attitudes, and actions. The

objective was achieved through a survey of residents in four Carolinian Zone municipalities, two

with an UFMP.

Overall, native tree species are more identifiable by residents compared to commonly planted

non-native tree species, but knowledge-levels are low, with only one-quarter of the commonly

planted species correctly identified by more than half of the participants. Respondents’

knowledge was not correlated with the presence or absence of an UFMP in their municipality,

which is likely because of the short period of time that the UFMPs have been in place and poor

communication of the plans’ goals, as expressed by several survey participants, indicating a lack

of engagement. Additionally, residents of British or European origin demonstrated a higher

knowledge of urban forest topics, and residents’ length of residency was related to knowledge of

the native-status of tree species, suggesting that engagement is uneven among different

communities in the study area and that people living in a community for a long period of time

tend to be knowledgeable about and engage in community activities (Romig, 2010; Williams and

Stewart, 1998). However, there was no relationship between knowledge of tree species and place

of birth, likely due to a failure in childhood education to expose children to forest and ecosystem

issues (Palmberg et al., 2015). Finally, it was found that respondents’ knowledge is correlated

with having planted trees on their property, though it is unclear whether they were

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knowledgeable about trees’ native-status before planting, or if the experience offered the

learning opportunity.

This chapter highlights the need for better outreach to all members of the community, to ensure

basic knowledge about urban forestry topics and goals, especially if municipalities require

residents to actively support policy goals. Additionally, the findings raised questions about

communicating the importance of native species to diverse communities, including those with

high immigrant populations who may feel slighted by the terminology.

5.1.3 Resident Attitudes and Actions Regarding Native Tree Species and

Urban Forest Issues

The study conducted in Chapter 4 uses the same survey of Carolinian Zone residents as Chapter

3, to examine residents’ attitudes and actions towards native tree species to further illuminate the

role of this key actor in urban forest management. The survey results accentuate the need for

municipalities to more actively engage residents regarding the goals of their UFMPs to achieve

resident buy-in for these goals. Most residents expressed positive attitudes towards native species

and were vastly in favour of their neighbours and the municipality planting more native trees.

Additionally, most respondents indicated that if given the choice between trees with similar

attributes they would choose the native tree. However, positive attitudes did not relate to having

native trees on their property or to support for the planting of native species regardless of costs,

and in the event that native trees could cause hazards or had higher maintenance costs, then

residents showed little support for them.

100

There was a strong relationship between respondent’s level of education and positive attitudes

towards native tree species, which is similar to other urban forest studies that have noted a

relationship between education-level and participation in urban forest activities (Conway and

Shakeel, 2014; Grove et al., 2006; Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et

al., 2012; Tooke et al., 2010; Zhang and Zheng, 2011; Zhang et al., 2007). Residents born

outside of Canada indicated less support for native trees as compared to those who live in the

municipality where they were born, which relates to findings in Chapter 3 that immigrants are

less knowledgeable about urban forest issues.

While the vast majority of residents believed that native species are more beneficial in urban

areas, the motivations that drive their tree planting actions are dominated by pragmatic, property-

level concerns such as the size and shape of the tree, amount of maintenance required, shade

provision, and aesthetic-value placed on the tree. This difference between attitudes and actions

was also observed in relation to municipal planting, as few respondents thought the municipality

should plant more non-native trees, but residents did not prioritize native species when given the

opportunity to choose their municipal boulevard tree. This also explains why the majority of

residents have positive native tree attitudes, but do not support planting species that could cause

additional maintenance costs or hazards.

This pragmatic relationship between residents and native trees supports findings that native tree

availability from nurseries and garden centres may play a large role in the structure of the urban

forest (Brzuszck et al., 2007; Conway and Vander Vecht, 2015; Polakowski et al., 2011; Sydnor

et al., 2010). Since the majority of urban residents acquire the trees planted on their property

from nurseries and garden centres, their choice of tree is limited to what is in stock (Sydnor et

101

al., 2010). Furthermore, nursery employees are not necessarily advocates of native tree species,

and may not have the knowledge to recommend a suitable native tree to meet residents stated

requirements (Polakowski et al., 2011).

By examining municipal planning documents, interviewing municipal foresters, and surveying

urban residents, this original research has addressed several gaps in the existing literature,

including: municipal considerations of native tree species in UFMPs, ecosystem services,

ecological integrity, and assisted migration; willingness of urban foresters to adopt the goals of

UFMPs; the role of residents in managing the urban forest and their knowledge, attitudes, and

actions regarding native tree species and urban forest issues; and, the impact of residents’ socio-

demographics on their urban forest knowledge, attitudes, and actions. By addressing these

knowledge gaps this dissertation is contributing a deeper understanding of the effects of urban

forest policy and outreach on municipal actors and residents in urban areas, while also

considering managing native species for ecosystem services and improved ecological integrity.

5.2 Recommendations for Management and Future Research

5.2.1 Management Recommendations

While this research has contributed to filling many knowledge gaps, several management and

future research recommendations have also emerged that could further contribute to

understanding native species management and urban forest policy interactions. Firstly, there is an

opportunity for municipalities to align the development of their planting lists with UFMPs stated

goals of increased native species presence to more easily achieve these goals, especially among

municipalities who have not yet adopted a management plan. Moreover, if a municipality

102

chooses to use native tree species planting to achieve ecological integrity, they should be clear

that it will require planting less common native species to ensure high native richness, so that

they are not creating a non-diverse, but a native urban forest; this may not be the same as

maximizing ecosystem services.

Another challenge associated with operationalizing ecological integrity through native species

planting is the limited availability of native species and difficulty of establishing the provenance

of the trees acquired. In Carolinian Canada, tree nurseries are often not able to meet the requests

of municipalities, limiting the species that can be planted. This is consistent with the findings of

Sydnor et al. (2010), who identified a mismatch between species urban foresters request and

those available from suppliers. This limited availability of native trees in nurseries represents an

added challenge to planting native trees and establishing local provenance. Municipalities should

explore development of local seed sources from the extant forest networks within their

community to improve their access to low-cost native trees.

Second, since the majority of residents` actions appear to be guided by pragmatic decision-

making that prioritizes aesthetics and tree functions over nativeness, a systemic approach that

involves altering the species availability at the place of purchase (nurseries and garden centres)

to represent a richer diversity of native trees would likely alter residents` actions in support of

native species diversity. A first step that municipalities can take is to require more native species

diversity and quantity in their tree-planting request for tenders from nurseries, as municipalities

are very large contracts, and this request should cause the nurseries to adjust their supply of

native trees. In some instances, this type of supply-chain influence has been found to be more

effective than educating residents (Summit and Sommer, 1998). Though residents may still

103

choose trees based on their aesthetic and functional value, if a higher number of native tree

species are available at the nursery, then the ratio of native to non-native trees will likely

increase through residential plantings.

Third, most Carolinian Zone municipalities in this study are passively practicing assisted

migration, by planting species from a more southerly zone because they are available and will

grow. Given that there are several risks associated with assisted migration, if municipalities are

practicing it then their actions should be managed thoughtfully by actively choosing which

species to translocate and monitoring their progress, rather than the more passive version that has

been widespread throughout the region.

Fourth, this study indicated a lack of effective urban forestry education and the particular need to

reach newer residents and those who have not previously planted trees. Fulfilling basic

knowledge criteria could be achieved through primary school programs that introduce students to

common urban tree species using a variety of learning methods that would likely help prepare

children to be good partners in municipal urban forestry initiatives. In addition to school

programs, municipalities should increase their use of traditional and social-media to help educate

residents about native tree species, as it can be a very effective tool for reaching new residents

(Lindgren, 2015), who it was found tend to be less knowledgeable about native tree species.

Unsurprisingly, a large-scale survey of American municipalities found that social media

communications are under-utilized by municipal governments (Graham and Avery, 2013),

suggesting its potential is not being realized. Given that presence of an UFMP was not

significantly related to native species attitudes, municipalities with native species planting goals

104

should be doing more education and outreach to ensure that residents are willing to prioritize

them when making species-selection decisions.

5.2.2 Future Research Recommendations

Future research studies are needed to understand if and to what extent preserving native diversity

is important for achieving ecosystem service provision and other goals unrelated to ecological

integrity, as well as understanding the functions and benefits that the novel assemblage of

primarily non-native species can provide to the municipality. At the same time, more native

species suitability trials must occur to determine these species’ tolerance to common urban tree

stressors and increase the usability of native trees as urban street trees. While several

interviewees commented on the high cost of species suitability trials, others suggested

coordinating and sharing this research amongst all Carolinian Zone municipalities through

existing forestry councils to reduce the burden of cost.

Similarly, municipalities lack species suitability information regarding assisted migration of

species from a more southerly zone. Keeping in mind that municipalities are bound by strict

financial and temporal budgets, this may best be achieved by partnering with colleges and

universities in the region to provide species suitability trial research and development.

Additionally, creating and investing in a municipal network that communicates the successes and

failures of planting experimental species under various growing conditions in Carolinian Canada

would eliminate the time and monetary cost of each municipality independently conducting these

trials, and as such, would be an efficient tool for operationalizing assisted migration across the

region. By doing so, municipalities could adaptively manage their urban forest, while also taking

steps to mitigate the anticipated effects of climate change.

105

The limited and uneven awareness that is reflected by survey participants in this study illustrates

a broader issue of uncertainty about how to engage with residents, particularly those who are not

already interested in urban forestry issues. Summit and Sommer (1998) described some basic

steps for engaging the public in urban forestry programs, including making the desired behavior

easy and clearly communicating the threat and actions that residents can take to address it.

While the study area municipalities are communicating with residents using tree planting

programs, the value of planting native species is still debated (D’Antonio and Meyerson, 2002;

Davis, 2012; Kendle and Rose, 2000; Sagoff, 2005; Schaeplfer et al., 2012) and there are many

instances where municipalities are choosing to plant non-native trees, making the desired

behaviour unclear, and not as simple as “plant more trees”. Thus, there is a need for consistent

messaging and future research that indicates different scenarios and methods to achieve an

effective partnership between municipal and resident actors, outlining successful methods of

municipal outreach.

In particular, reaching new residents, especially immigrant populations to facilitate their

knowledge acquisition about the local environment is a challenge. In addition, there is a need to

facilitate more positive attitudes towards native ecology amongst immigrants. Thus, cities like

Oakville and Markham, with sizable immigrant populations, may face additional challenges

about how to effectively communicate information in a way that will be inclusive. One strategy

to engage newcomers and residents of minority ethnic groups is to highlight the multicultural

nature of the urban forest itself, as common urban species originate from many parts of the world

(Johnston and Shimada 2004). However, this is at odds with management goals that emphasize

native trees. Thus, future research could help our understanding of how to effectively engage

with new residents, minority ethnic groups, and immigrant populations.

106

Future research action should also consider inclusion of apartment dwellers, as they were

purposefully excluded from this study given that they do not have space to plant trees on their

property, and as a result their knowledge, attitudes, and actions regarding native trees remain

unexamined. Similarly, to build upon the findings in this dissertation future research should

include case studies that investigate the meaning and influence of local and familiar places on

residents’ knowledge, attitudes, and actions related to native tree species, as this has been shown

to have an effect on local environmental decision-making in previous studies (Davenport and

Anderson, 2005; Gobster et al., 2007; Larson et al., 2009; Romig, 2010; Williams and Stewart,

1998). This would aid in the understanding of the complex motivations and reasoning behind

attitudes and actions as shown in this and other’s work surrounding local environmental issues.

107

References

Akbari, H., Taha, H., 1992. The impact of trees and white surfaces on residential heating and

cooling energy use in four Canadian cities. Energy 17, 141–149.

Alberti, M., 2010. Maintaining ecological integrity and sustaining ecosystem function in urban

areas. Current Opinion in Environmental Sustainability 2, 178-184.

Almas, A., Conway, T.M., 2016. The role of native species in municipal urban forest planning

and practice: A case study of Carolinian Canada. Urban Forestry and Urban Greening 17

(1), 54-62.

Almas, A., Conway, T.M., In press. Residential knowledge of native tree species: A case study

of residents in four southern Ontario municipalities. Environmental Management doi:

10.1007/s00267-016-0772-5.

Alpert, P., Bone, E., Holzapfel, C., 2000. Invasiveness, invasibility and the role of

environmental stress in the spread of non-native plants. Perspectives in Plant

Ecology, Evolution, and Systematics 3 (1), 52-66.

Alvey, A.A., 2006. Promoting and preserving biodiversity in the urban forest. Urban Forestry

and Urban Greening 5 (4), 195-201.

Andrew, C., Slater, D., 2014. Why some UK homeowners reduce the size of their front garden

trees and the consequences for urban forest benefits as assessed by i-Tree ECO.

Arboricultural Journal: The International Journal of Urban Forestry 36(4), 197-215.

Angermeier P.L.,1994. Does biodiversity include artificial diversity? Conservation Biology 8 (2),

600–602.

Anthon, S., Thorsen, B.J., Helles, F., 2005. Urban-fringe afforestation projects and taxable

hedonic values. Urban Forestry and Urban Greening 3, 79–91.

Arbuthnot, J., 1977. The roles of attitudinal and personality variables in the prediction of

environmental behavior and knowledge. Environment and Behaviour 9 (2), 217-232.

Armstrong, J. B., Impara, J. C., 1991. The impact of an environmental education program on

knowledge and attitude. Journal of Environmental Education 22 (4), 36–40.

Avolio, M., Pataki, D.E., Pincetl, S., Gillespie, T.W., Jenerette, G.D., McCarthy, H.R., 2015.

Understanding preferences for tree attributes: The relative effects of socio-economic and

local environmental factors. Urban Ecosystem 18, 73-86.

Balram, S., Dragićević, S., 2005. Attitudes toward urban green spaces: integrating questionnaire

survey and collaborative GIS techniques to improve attitude measurements. Landscape

and Urban Planning 71, 147-162.

108

Bardekjian, A., Kenney, A., Rosen, M., 2016. Trends in Canada’s urban forests. Tree Canada

and The Canadian Urban Forest Network.

Barro, S. C., Gobster, P. H., Schroeder, H. W., Bartram, S. M., 1997. What makes a big tree

special? Insights from the Chicagoland treemendous trees program. Journal of

Arboriculture 23, 239-249.

Baur, A., Haase, H., 2015. The influence of active participation and organization in

environmental protection activities on the environmental behaviour of pupils: study of a

teaching technique. Environmental Education Research 21 (1), 92-105.

Bertin, R.I., Manner, M.E., Larrow, B.F., Cantwell, T.W., Berstene, E.M., 2005. Norway maple

(Acer platanoides) and other non-native trees in urban woodlands of central

Massachusetts. Journal of the Torrey Botanical Society 132 (2), 225-235.

Bolund, P., Hunhammar, S., 1999. Ecosystem services in urban areas. Ecological Economics 29,

293–301.

Boone, C.G., Cadenasso, M.L., Grove, J.M., Schwarz, K., Buckley, G.L., 2010. Landscape,

vegetation characteristics, and group identify in an urban and suburban watershed: why

the 60s matter. Urban Ecosystem 13, 255–271.

Brzuszek, R.F., Harkess, R.L., Mulley, S.J., 2007. Landscape architects’ use of native plants

in the southeastern United States. Horttechnology 17, 78–81.

Camacho, A.E., 2010. Assisted migration: Redefining nature and natural resource law under

climate change. Yale Journal on Regulation 27, 171-255.

Camacho-Cervantes, M., Schondube, J.E., Castillo, A., MacGregor-Fors, I., 2014. How do

people perceive urban trees? Assessing likes and dislikes in relation to the trees of a city.

Urban Ecosystem 17, 761–773.

Carrier, S., 2009. Environmental education in the schoolyard: Learning styles and gender. The

Journal of Environmental Education 40 (3), 2-12.

Chawla, L., 1999. Life paths into effective environmental action. The Journal of Environmental

Education 3 (1), 15–26.

Chipeniuk, R., 1995. Childhood foraging as a means of acquiring competent human cognition

about biodiversity. Environment and Behavior 27 (4), 490–512.

Cilliers, S., Siebert S., Davoren, E., Lubbe, R., 2012. Social aspects of urban ecology in

developing countries with emphasis on urban domestic gardens. Pages 123-135 in

Richter, M., and Weiland, U., editors. Applied Urban Ecology: A Global Framework.

Wiley-Blackwell, Oxford, UK.

109

City of Burlington, 2010. Urban Forest Management Plan: 2011-2030. 1-60.

City of St. Catharines, 2011. Urban Forestry Management Plan. 1-69.

City of Guelph, 2012. Urban Forest Management Plan: 2013-2032. 1-131.

City of Halifax, 2012. Halifax Regional Municipality Urban Forest Master Plan. 1-465.

City of London, 2014. City of London Urban Forest Strategy. 1-46.

City of Mississauga, 2014. Urban Forest Management Plan. 1-124.

City of Toronto, 2013. Sustaining and Expanding the Urban Forest: 2013-2032: 1-76.

Clark, J., Matheny, N., Cross, G., Wake, V., 1997. A model of urban forest sustainability.

Journal of Arboriculture 23 (1), 17-30.

Clemants, S., Moore, J., 2003. Patterns of species richness in eight northeastern United States

cities. Urban Habitats 1 (1), 4-16.

Colding, J., Elmqvist, T., Lundberg, J., Ahrne, K., Andersson, E., Barthel, S., Borgstrom, S.,

Duit, A., Ernstsson, H., Tengo, M., 2003. The Stockholm urban assessment

(SUASweden). Millennium Ecosystem Assessment Sub-Global Summary Report,

Stockholm.

Collins, J., Kinzig, A., Grimm, N. B., Fagan, W., Wu, J., Borer, E., 2000. A new urban ecology.

American Scientist 88, 416–425.

Conway, T.M., 2016. Tending their urban forest: residents’ motivations for tree planting and

removal. Urban Forestry and Urban Greening 17 (1), 23-32.

Conway, T.M., Shakeel T., Attallha J., 2011. Community groups and urban forestry activity:

drivers of uneven canopy cover? Landscape and Urban Planning 101 (4), 321-329.

Conway, T.M., Shakeel, T., 2014. Individual households and their trees: Fine-scale

characteristics shaping urban forests. Urban Forestry and Urban Greening 13, 136-144.

Conway, T.M., Urbani, L., 2007. Variations in municipal urban forestry policies: a case study for

Toronto, Canada. Urban Forestry and Urban Greening 6 (3), 181-192.

Conway, T.M., Vander Vecht, J., 2015. Growing a diverse urban forest: species selection

decisions by practitioners planting and supplying trees. Landscape and Urban Planning

138, 1-10.

Corcoran, P., 1999. Formative influences in the lives of environmental educators in the United

States. Environmental Education Research 5 (2), 207–220.

110

D’Antonio, C., Meyerson, L.A., 2002. Exotic plant species as problems and solutions in

ecological restoration: A synthesis. Exotic Plant Species and Restoration 10 (4), 703-

713.

Davenport, M.A., Anderson, D.H., 2005. Getting from sense of place to place-based

management: an interpretive investigation of place meanings and perceptions of

landscape change. Society and Natural Resources 18, 625–641.

Davis, M., 2012. Do native birds care whether their berries are native or exotic? no. Bioscience

61 (7), 501-502.

Day, S.D., Bassuk, N.L. van Es, H., 1995. Effects of fours compaction remediation methods for

landscape trees on soil aeration, mechanical impedance and tree establishment. Journal of

Environmental Horticulture 13, 64–71.

DeGraff, R.M., Payne, B.R., 1975. Economic values of nongame birds and some research

needs, Trans North American Wildlife and Natural Resources Conference 40, 281-287.

de Groot, R.S., Wilson, M.A., Boumans, R.M.J., 2002. A typology for the classification,

description and valuation of ecosystem functions, goods and services. Ecological

Economics 41, 393-408.

Dillman, D.A., 2007. Mail and Internet Surveys: The Tailored Design Method, 2nd ed. New

York, John Wiley.

Dobbs, C., Escobedo, F.J, Zipperer, W.C., 2011. A framework for developing urban forest

ecosystem services and goods indicators. Landscape and Urban Planning 99, 196-206.

Duinker, P., Ordonez, C., Steenburg, J., Miller, K., Toni, S., Nitoslawski, S., 2015. Trees in

Canadian cities: Indispensable life form for urban sustainability. Sustainability 7, 7379-

7396.

Dunphy, A., Spellman, G., 2009. Geography fieldwork, fieldwork value and learning styles.

International Research in Geographical and Environmental Education 18 (1), 9-28.

Dwyer, J.F., Schroeder, H.W., 1994. The human dimensions of urban forestry, Journal of

Forestry 92 (10), 12-15.

Elmendorf, W., Watson, T., Lilly, S., 2005. Arboriculture and urban forestry education in the

United States: Results of an educator’s survey. Journal of Arboriculture 31 (3), 138-149.

Elmendorf, W., 2008. The importance of trees and nature in community: A review of the relative

literature. Arboriculture and Urban Forestry 34, 152–156.

Escobedo, F.J., Kroeger, T., Wagner, J.E., 2011. Urban forests and pollution mitigation:

Analyzing ecosystem services and disservices. Environmental Pollution 159, 2078-2087.

111

Farrar, J.L., 1995. Trees in Canada. Fitzhenry and Whiteside: Toronto.

Finger, M., 1994. From knowledge to action—Exploring the relationships between

environmental experiences, learning, and behavior. Journal of Social Issues 50 (3),141–

160.

Fishbein, M., Ajzen, I., 2010. Predicting and changing behavior: The reasoned action

approach. New York: Psychology Press.

Fleming, J.J., Straka, T.J., Miller, S.E., 2006. An econometric model to predict participation in

urban and community forestry programs in South Carolina. U.S. Arboriculture and

Urban Forestry 32 (5), 229–235.

Folke, C., Carpenter, S., Walker, B., Scheffer, M., Elmqvist, T., Gunderson, L., Holling, C.S.,

2004. Regime shifts, resilience, and biodiversity in ecosystem management. Annual

Review of Ecology, Evolution, and Systematics 35, 557–581.

Forest School Canada, 2014. Forest and Nature School in Canada: A Head, Heart, Hands

Approach to Outdoor Learning. Retrieved April 25, 2016.

Fraser, E., Kenney, W., 2000. Cultural background and landscape history as factors affecting

perceptions of the urban forest. Journal of Arboriculture 26 (2), 106-113.

Gilman, E.F., 1988. Prediction of root spread from trunk diameter and branch spread. Journal of

Arboriculture 14, 85–89.

Gobster, P.H., Nassauer, J.I., Daniel, T.C., Fry, G., 2007. The shared landscape: what does

aesthetics have to do with ecology? Landscape Ecology 22 (7), 959–972.

Gobster, P.H., Westphal, L.M., 2004. The human dimensions of urban greenways: Planning for

recreation and related experiences. Landscape and Urban Planning 68, 147–165.

Gorman, J., 2004. Residents’ opinions on the value of street trees depending on tree location.

Journal of Arboriculture 30 (1), 36-44.

Graham, M., Avery, E., 2013. Government public relations and social media: An analysis of the

perceptions and trends of social media use at the local government level. Public Relations

Journal 7 (4) 1-21.

Gray, E., van Heezik, Y., 2016. Exotic trees can sustain native birds in urban woodlands. Urban

Ecosystems 19 (1), 315-329.

Greene, C., Millward, A., Ceh, B., 2011. Who is likely to plant a tree? The use of public socio-

demographic data to characterize client participants in a private urban forestation

program. Urban Forestry and Urban Greening 10 (1), 29-38.

112

Grimm, N., Redman, C., Boone, C., Childers, D., Harlan, S., Turner, B., 2013. Viewing the

Urban Socio-ecological System Through a Sustainability Lens: Lessons and Prospects

from the Central Arizona–Phoenix LTER Programme. In: Singh, S., Haberl, H., Chertow,

M., Mirtl, M., Schmid, M. (Eds.), Long Term Socio-Ecological Research. Springer: New

York, pp. 217-246.

Grove, J., Cadenasso, M., Burch, W., 2006. Data and Methods comparing social structure and

vegetation structure of urban neighbourhoods in Baltimore, Maryland. Society and

Natural Resources 19 (2), 117-136.

Gustafsson, L., 2002. Presence and abundance of red-listed plant species in Swedish forests.

Conservation Biology 16, 377–388.

Heisler, G.M., 1990. Tree plantings that save energy. In Proceedings of the 4th National Urban

Forestry Conference, (P. Rodbell, ed.), American Forestry Association, Washington, DC,

58-62.

Hermoso, V., Clavero, M., 2013. Revisiting ecological integrity 30 years later: non-native

species and the misdiagnosis of freshwater ecosystem health. Fish and Fisheries 14 (3),

416-423.

Hewitt, N., Klenk, N., Smith, A.L., Bazely, D.R., Yan, N., Wood, S., MacLellan, J.I., Lipsig-

Mumme, C., Henriques, I., 2011. Taking stock of the assisted migration debate.

Biological Conservation 144, 2560-2572.

Heynen, N., Lindsay, G., 2003. Correlates of urban forest canopy cover: implications for local

public works. Public Works Management and Policy 8 (1), 33–47.

Heynen, N., Perkins, H., Roy, P., 2006. The political ecology of uneven green space: The impact

of political economy on race and ethnicity in producing environmental inequality in

Milwaukee. Urban Affairs Review 42 (1), 3-25.

Hitchmough, J., 2011. Exotic plants and plantings in the sustainable, designed urban landscape.

Landscape and Urban Planning 100, 380-382.

Hull, R.B.; Lamb, M.; Vigob, G., 1994. Place identity: Symbols of self in the urban fabric.

Landscape and Urban Planning 28, 109–120.

Imhoff, M.L., Zhang, P., Wolfe, R.E., Bounoua, L., 2010. Remote sensing of the urban heat

island effect across biomes in the continental USA. Remote Sensing of Environment 114,

504-513.

IPCC, 2001. Climate Change 2001: The Scientific Basis. Chapter 2.2 How much is the world

warming?.

Johnson, L. (Ed.), 2007. The Natural Treasures of Carolinian Canada. Lorimer Publishers,

Toronto.

113

Johnston, M., Shimada, L.D., 2004. Urban forestry in a multicultural society. Journal of

Arboriculture 30 (3), 185-192.

Jones, R., Davis, K., Bradford, J. 2012. The value of trees: Factors influencing homeowner

support for protecting local urban trees. Environment and Behaviour 45 (5), 650-676.

Jorgensen, E., 1970. Urban forestry in Canada, In: Proceedings of the 46th International Shade

Tree Conference, 53a-51a.

Kaplan, R., Herbert, E.J., 1987. Cultural and subcultural comparisons in preferences for natural

settings. Landscape and Urban Planning 14, 281-293.

Kendal, D., Williams, N., Williams, K., 2012. Drivers of diversity and tree cover in gardens,

parks, and streetscapes in an Australian city. Urban Forestry and Urban Greening 11,

257-265.

Kendle, A., Rose, J., 2000. The aliens have landed! What are the justifications for native only

policies in landscape plantings? Landscape and Urban Planning 47, 19-31.

Kenney, A., van Wassenaer, P., Satel, A., 2011. Criteria and indicators for strategic urban

forest planning and management. Arboriculture and Urban Forestry 37 (3), 108-117.

Kirkpatrick, J.B., Davison, A., Daniels, G.D., 2012. Resident attitudes towards trees influence

the planting and removal of different types of trees in eastern Australian cities. Landscape

and Urban Planning 107, 147-158.

Kolb, D., 1984. Experiential Learning: Experience as the Source of Learning and Development.

Prentice-Hall.

Kong, F., Yin, H., Nakagoshi, N., 2007. Using GIS and landscape metrics in the hedonic price

modeling of the amenity value of urban green space: a case study in Jinan City, China.

Landscape and Urban Planning 79, 240–252.

Konijnendijk, C., Ricard, R., Kenney, A., Randrup, T., 2006. Defining urban forestry – A

comparative perspective of North America and Europe. Urban Forestry and Urban

Greening 4, 93-103.

Kowarik, I., 1995. On the Role of Alien Species in Urban Flora and Vegetation. In: Pysek, P.,

Prach, K., Rejmanek, M., Wade, M. (Eds.). Plant Invasions – General aspects and

special problems. SPB Academic Publishing, 85-103.

Kowarik, I., 2011. Novel urban ecosystems, biodiversity, and conservation. Environmental

Pollution 159 (8-9), 1974-1983.

Kuhn, I., Brandl, R., Klotz, S., 2004. The flora of German cities is naturally species rich.

Evolutionary Ecology Research 6, 749–764.

114

Kuo, F.E., Sullivan, W.C., 2001. Aggression and violence in the inner city: Effects of

environment via mental fatigue. Environmental Behaviour 33, 543–571.

Kurz, T., Baudains, C., 2012. Biodiversity in the front yard: An investigation of landscape

preference in a domestic urban context. Environment and Behaviour 44 (2), 166-196.

Landry, S.M., Chakraborty, J., 2009. Street trees and equity: evaluating the spatial distribution of

an urban amenity. Environment and Planning 41, 2651-2670.

Larson, K.L., Casagrande, D., Harlan, S.L., Yabiku, S.T., 2009. Residents’ yard choices and

rationales in a desert city: social priorities, ecological impacts, and decision tradeoffs.

Environmental Management 44 (5), 921–937.

Larson, K.L., Cook, E., Strawhacker, C., Hall, S.J., 2010. The influence of diverse values,

ecological structure, and geographic context on residents’ multifaceted landscaping

decisions. Human Ecology 38, 747-761.

Lee, A., Maheswaran, R., 2011. The health benefits of urban green spaces: A review of the

evidence. Journal of Public Health 33, 212–222

Ligeti, E., 2007. Climate change adaptation options for Toronto’s urban forest. Clean Air

Partnership, Toronto.

Lindemann-Matthies, P., 2006. Investigating nature on the way to school: Responses to an

educational programme by teachers and their pupils. International Journal of Science

Education 28, 895–918.

Lindgren, A., 2015. Municipal communication strategies and ethnic media: A settlement service

in disguise. Global Media Journal, Canadian ed. 8 (2), 49-71.

Livesley, S., McPherson, E., Calfapietra, C., 2016. The urban forest and ecosystem services:

Impacts on urban water, heat, and pollution cycles at the tree, street and city scale.

Journal of Environmental Quality 45, 119-124.

Locke, D.H., Grove, J.M., 2016. Doing the hard work where it’s easiest? Examining the

relationship between urban greening programs and social and ecological characteristics.

Applied Spatial Analysis 9, 77-96.

Lohr, V. I., C. H. Pearson-Mims., 2005. Children’s active and passive interactions with plants

influence their attitudes and actions toward trees and gardening as adults. Horttechnology

15, 472–476.

Luck, G., Smallbone, L., O’Brien, R., 2009. Socio-economics and vegetation change in urban

ecosystems: Patterns in space and time. Ecosystems 12, 604-620.

115

Luckmann, K., Menzel, S., 2014. Herbs versus trees: influences on teenagers’ knowledge of

plant species. Journal of Biological Education 48 (2), 80-90.

Lyytimäki, J., Sipilä, M., 2009. Hoping on one leg-the challenge of ecosystem disservices

for urban green management. Urban Forestry and Urban Greening 8, 309–315.

Majumdar, S.; Deng, J.; Zhang, Y.; Pierskalla, C., 2011. Using contingent valuation to estimate

the willingness of tourists to pay for urban forests: A study in Savannah, Georgia. Urban

Forestry and Urban Greening 10, 275–280.

Marco, A., Barthelemy, C., Dutoit, T., Bertaudière-Montes, V., 2010. Bridging human and

natural sciences for a better understanding of urban floral patterns: the role of planting

practices in Mediterranean gardens. Ecology and Society 15 (2), 2.

Martin, L.E., Sorice, M.G., Kreuter, U.P., 2013. Understanding and influencing urban resident’s

knowledge about wildlife management in Austin, Texas. Urban Ecosystems 16, 33-51.

McDonald-Madden, E., Runge, M.C., Possingham, H.P., Martin, T.G., 2011. Optimal timing for

managed relocation of species faced with climate change. Nature Climate Change 1, 261-

265.

McKinney, M., 2002. Urbanization, biodiversity, and conservation. BioScience 52 (10), 883-890.

McLachlan, J., Hellmann, J., Schwartz, M., 2007. A framework for debate of assisted migration

in an era of climate change. Conservation Biology 21 (2), 297-302.

McPherson, E. G. 1998. Structure and sustainability of Sacramento’s urban forest. Journal of

Arboriculture 24 (4), 174–90.

McPherson, E.G., Muchnick, J., 2005. Effects of street tree shade on asphalt concrete pavement

performance. Journal of Arboriculture 31, 303–310.

Meehl, G.A., Stocker, T.F., Collins, W.D., Friedlingstein, P., Gaye, A.T., Gregory, J.M., Kitoh,

A., Knutti, R., Murphy, J.M., Noda, A., Raper, S.C.B., Watterson, I.G., Weaver, A.J.,

Zhao, Z.-C., 2007. Global climate projections. Climate Change 2007: The Physical

Science Basis. Cambridge University Press: New York, 757–845.

Mehmood, S., Zhang, D., 2001. A roll call analysis of the Endangered Species Act amendments.

American Journal of Agricultural Economics 83, 501–512.

Meyer, S.E., 2005. Intermountain Native Plant Growers Association: A nonprofit trade

organization promoting landscape use of native plants. Native Plants Journal 6 (2), 104–

107.

Miller, J.R., Hobbs, R.J., 2002. Conservation where people live and work. Conservation Biology

16, 330–337.

116

Mincey, S., Hutten, M., Fischer, B., Evans, T., Stewart, S., Vogt, J., 2013. Structuring

institutional analysis for urban ecosystems: A key to sustainable urban forest

management. Urban Ecosystems 16, 553-571.

Ministry of Natural Resources, 2000. The Big Picture Project: Developing a Natural Heritage

Vision for Carolinian Canada. Ontario Natural Heritage Information Centre Newsletter 6

(1), 1-5.

Morgenroth, J., Östberg, J., Konijnendijk, C., Nielsen, A., Hauer, R., Sjöman, H., Chen, W.,

Jansson, M., 2016. Urban tree diversity – Taking stock and looking ahead. Urban

Forestry and Urban Greening 15, 1-5.

Neville, L.R., 1996. Urban watershed management: The role of vegetation. Ph.D. diss., SUNY

College of Environmental Science and Forestry, Syracuse, NY.

Nowak, D.J., Dwyer, J.F., 2007. Understanding the benefits and costs of urban forest

ecosystems. In: Kuser, J.E. (Ed.), Urban and Community Forestry in the Northeast.

Springer, New York, pp. 25-46.

Nowak, D.J., 2012. Contrasting natural regeneration and tree planting in fourteen North

American cities. Urban Forestry and Urban Greening 11, 374-382.

Olive, A., Rusch, L., Ayers, A., 2013. Public Perceptions of the Value of Urban Trees in the

River Rouge Watershed. Michigan Academician XLI, 310-331.

Olive, A., 2014. Urban awareness and attitudes toward conservation: A first look at Canada’s

cities. Applied Geography 54, 160-168.

"Ontario Climate". 2011. Ontario Ministry of Agriculture, Food and Rural Affairs. Retrieved

June 3, 2011.

Ordonez, C. Duinker, P.N., 2012. Ecological integrity in urban forests. Urban Ecosystems 15,

863-877.

Ordonez, C., Duinker, P.N., 2013. An analysis of urban forest management plans in Canada:

Implications for urban forest management. Landscape and Urban Planning 116, 36-47.

Ordonez, C., Duinker, P.N., 2014. Assessing the vulnerability of urban forests to climate change.

Environmental Review 22, 311-321.

Palmberg, I., Kuru, J., 2000. Outdoor activities as a basis for environmental responsibility. The

Journal of Environmental Education 31 (4), 32–36.

Palmberg, I. Berg, I., Jeronen, E., Kärkkäinen, S., Norrgård-Sillanpää, P., Persson, C., Vilknois,

R., Yli-Panula, E., 2015. Nordic–Baltic Student Teachers’ Identification of and Interest in

Plant and Animal Species: The Importance of Species Identification and Biodiversity for

Sustainable Development. Journal of Science Teacher Education 26 (6), 549-571.

117

Palmer, J. A., Suggate, J., Robottom, I., Hart, P., 1999. Significant life experiences and formative

influences on the development of adults’ environmental awareness in the UK, Australia

and Canada. Environmental Education Research 5 (2), 181–200.

Pataki D.E., Carreiro M.M., Cherrier J., et al., 2011. Coupling biogeochemical cycles in urban

environments: ecosystem services, green solutions, and misconceptions. Frontiers in

Ecology and the Environment 9, 27–36.

Pauleit, S., Jones, N., Garcis-Martin, G., Garcia-Valdecantos, J., Riviere, L., Vidal-Beaudet, L.,

Bodson, M., Randrup, T., 2002. Tree establishment practise in towns and cities – result

from a European survey. Urban Forestry and Urban Greening 1 (2), 83–9.

Pedlar, J.H., McKenney, D.W., Aubin, I., Beardmore, T., Bealieu, J., Iverson, L., O’Neill, J.A.,

Winder, R.S., Ste-Marie, C., 2012. Placing forestry in the assisted migration debate.

BioScience 62 (9), 835-842.

Peel Region, 2011. Urban Forest Strategy. 1-94.

Perkins, H., Heynen, N., 2004. Inequitable access to urban reforestation: The impact of urban

political economy on housing tenure and urban forests. Cities 21 (4), 291-299.

Perkins, H., Roy, P., Heynen, N., 2006. The Political Ecology of Uneven Urban Green

Space. Urban Affairs Review 42 (1), 3–25.

Pham, T., Apparicio, P., Seguin, A., Landry, S., Gagnon, M., 2012. Spatial distribution of

vegetation in Montreal: An uneven distribution or environmental equity? Landscape and

Urban Planning 107 (3), 214-224.

Pincetl, S., Prabhu, S. S., Gillespie, T. W., Jenerette, G. D., Pataki, D. E., 2013. The evolution

of tree nursery offerings in Los Angeles County over the last110 years. Landscape and

Urban Planning 118, 10–17.

Polakowski, N.R., Lohr, V.I., Cerny-Koenig, T., 2011. Survey of wholesale production nurseries

indicates need for more education on the importance of plant species diversity.

Arboriculture and Urban Forestry 37 (6), 259–264.

Quigley, M., 2004. Street trees and rural conspecifics: Will long-lived trees reach full size in

urban conditions? Urban Ecosystems 7, 29-39.

Raupp, M.J., Cumming, A.B., Raupp, E.C., 2006. Street Tree Diversity in Eastern North

America and its Potential for Tree Loss to Exotic Borers. Arboriculture and Urban

Forestry 32 (6), 297-303.

Reid, 2002. Practical Options for the Greening of Carolinian Canada. Bobolink Enterprises.

Washago, Ontario.

118

Romig, K., 2010. Community and social capital in upper-income neighborhoods: an

investigation in metropolitan Phoenix. Urban Geography 31 (8), 1065–1079.

Rotherman, I., Lambert, R. (eds.), 2013. Invasive and Introduced Plants and Animals: Human

Perceptions, Attitudes and Approaches to Management. Routledge, London.

Rubin, H. R., Owens, A. J., Golden, G., 1998. Status Report: An Investigation to Determine

Whether the Built Environment Affects Patients’ Medical Outcomes. Martinez, CA: The

Center for Health Design.

Sagoff, M., 2005. Do non-native species threaten the natural environment? Journal of

Agricultural and Environmental Ethics 18, 215-236.

Sanders, R.A., 1986. Urban vegetation impacts on the urban hydrology of Dayton Ohio, Urban

Ecology 9, 361-376.

Sax, D.F., Gaines, S.D., 2003. Species diversity: from global decreases to local increases. Trends

in Ecology and Evolution 18 (11), 561-566.

Sax, D. F., Smith, K. F., Thompson, A. R., 2009. Managed relocation: A nuanced evaluation is

needed. Trends in Ecology and Evolution 24 (9), 472.

Schaelpfer, M.A., Sax, D.F., Olden, J.D., 2012. Toward a more balanced view of non-native

species. Conservation Biology 26 (6), 1156-1158.

Schroeder, H., Flannigan, J., Coles, R. (2006). Residents’ attitudes toward street trees in the

UK and U.S. communities. Arboriculture and Urban Forestry 32, 236-246.

Seabrook-Davison, M., Brunton, D., 2014. Public attitude towards conservation in New

Zealand and awareness of threatened species. Pacific Conservation Biology, 20 (3), 286

-295.

Sjöman, H., Morgenroth, J., Sjöman, J., Sæbø, A., Kowarik, I., 2016. Diversification of the urban

forest – can we afford to exclude exotic tree species? Urban Forestry and Urban Greening

18, 237-241.

Sjoman, H., Nielsen, A.B., 2010. Selecting trees for urban paved sites in Scandinavia – A review

of information on stress tolerance and its relation to the requirements of tree planners.

Urban Forestry and Urban Greening 9, 281-293.

Sjoman, H., Ostberg, J., Buhler, O., 2011. Diversity and distribution of the urban tree population

in ten major Nordic cities. Urban Forestry and Urban Greening 11, 31-39.

Slimak, M.W., Dietz, T., 2006. Personal values, beliefs, and ecological risk perception. Risk

Analysis 26, 1689–1705.

Smith, W.H., 1990. Air Pollution and Forests, Springer-Verlag, New York.

119

Smout, T. C., 2000. Nature Contested: Environmental History in Scotland and Northern

England since 1600. Edinburgh: Edinburgh University Press.

Somer, R., Learey, F., Summit, J., Tirrell, M., 1994. The social benefits of resident involvement

in tree planting. Journal of Arboriculture 20 (3), 170-174.

Statistics Canada, 2011. Stats Canada 2011 Canadian Census: Hamilton, Ontario. Retrieved

January 12, 2014.

Statistics Canada, 2011. Stats Canada 2011 Canadian Census: London, Ontario. Retrieved

January 12, 2014.

Statistics Canada, 2011. Stats Canada 2011 Canadian Census: Markham, Ontario. Retrieved

January 12, 2014.

Statistics Canada, 2011. Stats Canada 2011 Canadian Census: Oakville, Ontario. Retrieved

January 12, 2014.

Statistics Canada, 2011. National Household Survey, 2011. Retrieved January 29, 2016.

Statistics Canada, 2015. NHS: Data quality. http://www12.statcan.gc.ca/NHS

ENM/2011/ref/about-apropos/nhs-enm_r005-eng.cfm. Accessed 28 July 2015.

Ste-Marie, C., Nelson, E.A., Dabros, A., Bonneau, M., 2011. Assisted migration: introduction to

a multi-faceted concept. The Forestry Chronicle 87 (6), 724-730.

Stewart, G.H., Ignatieva, M.E., Meurk, C.D., Earl, R.D., 2004. The re-emergence of indigenous

forest in an urban environment, Christchurch, New Zealand. Urban Forestry and Urban

Greening 2, 149–158.

Summit, J., McPherson, E.G., 1998. Residential tree planting and care: a study of attitudes and

behavior in Sacramento, California. Journal of Arboriculture 24, 89–96.

Summit, J., Sommer, R., 1998. Urban Tree Planting Programs – A Model for Encouraging

Environmentally Protective Behaviour. Atmospheric Environment 32 (1), 1-5.

Sydnor, T.D., Subburayalu, S., Bumgardner, M., 2010. Contrasting Ohio nursery stock

availability with community planting needs. Arboriculture and Urban Forestry 36

(1), 47–54.

Tooke, T., Klinkenberg, B., Coops, N., 2010. A geographical approach to identifying vegetation-

related environmental equity in Canadian cities. Environment and Planning B: Planning

and Design 37, 1040-1056.

Town of Ajax, 2011. Urban Forest Management Plan: Comprehensive Plan: 2011-2015. 1-155.

120

Town of Oakville, 2008. Urban Forest Strategic Management Plan: 2008-2027. 1-213.

Transek, 1993. Vardering av miljofaktorer (Valuation of environmental aspects). Transek, Solna

(in Swedish) 115.

Troy, A., Girve, J., O’Neil-Dunne, S., Pickett, S., and Cadenasso, M., 2007. Predicting

opportunities for greening and patterns of vegetation on private urban lands.

Environmental Management 40, 394-412.

Tyrväinen, L., 1997. The amenity value of the urban forest: an application of the hedonic pricing

method. Landscape and Urban Planning 37, 211–222.

Ulrich, R., 1981. Natural versus urban scenes: Some psychophysiological effects. Environment

and Behaviour 13, 523-556.

Ulrich, R., 1984. View through a window may influence recovery from surgery. Science 224,

420-421.

United Nations Population Division (UNPD), 2010. World urbanization prospects: The 2009

revision. New York: United Nations Population Division.

van Wassenaer, P., Kenney, W., 2000. Strategic Urban Forest Planning. University of Toronto. 1-

17.

Vlek, C., Steg, L., 2007. Human Behaviour and Environmental Sustainability: Problems, Driving

Forces, and Research Topics. Journal of Social Issues 63 (1), 1-19.

Waldron, G., 2003. Trees of the Carolinian Forest. Boston Mills Press. Erin.

Watkins, S.L., Mincey, S.K., Vogt, J, Sweeney, S.P., 2016. An examination of the spatial

distribution of nonprofit urban tree-planting programs by canopy cover, income, race, and

ethnicity. Environment and Behavior, in press.

Wells, N.M., 2000. At home with nature: Effects of “greening” on children’s cognitive

functioning. Environment and Behaviour 32 (5), 775-795.

Williams, D.R., Stewart, S.I., 1998. Sense of place: an elusive concept that is finding a home

in ecosystem management. Journal of Forestry 96, 18–23.

Wolf, K.L., 2004. Trees and business district preferences: A case study of Athens, Georgia, US.

Journal of Arboriculture. 30, 336–346.

Wu, J., 2014. Urban ecology and sustainability: The state-of-the-science and future directions.

Landscape and Urban Planning 150, 209-221.

Xiao, Q., McPherson, E.G., Simpson, 1998. Rainfall interception by Sacramento’s urban forest.

Journal of Arboriculture 24 (4), 235–244.

121

Xiao, Q.; McPherson, E.G.; Ustin, S.L.; Grismer, M.E.; Simpson, J.R., 2000. Winter rainfall

interception by two mature open-grown trees in Davis, California. Hydrological

Processes 14, 763–784.

Young, R., 2013. Mainstreaming urban ecosystem services: A national survey of municipal

foresters. Urban Ecosystems 16, 703-722.

Zagorski, T., Kirkpatrick, J.B., Stratford, E., 2004. Gardens and the bush: gardeners’ attitudes,

garden types and invasive. Australian Geographical Studies 42 (2), 207–220.

Zahran, S., Brody, S., Grover, H., Vedlitz, A., 2006. Climate change vulnerability and policy

support. Society and Natural Resources 19, 771–789.

Zhang, Y., Hussain, A., Jinyang, D., Letson, N., 2007. Public attitudes toward urban trees and

supporting urban tree programs. Environment and Behavior 39, 797-814.

Zhang, Y., Zheng, B., 2011. Assessments of citizen willingness to support urban forestry: an

empirical study in Alabama. Arboriculture and Urban Forestry 37 (3), 118-125.

Zhu, K., Woodall, C., Clark, J., 2012. Failure to migrate: Lack of tree range expansion in

response to climate change. Global Change Biology 18 (3), 1042.

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Appendices

Appendix A – Written survey distributed to residents

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