Organic agriculture and ecosystem functions at farm and ...
Transcript of Organic agriculture and ecosystem functions at farm and ...
10/7/2009
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Organic agriculture and ecosystem
functions at farm and landscape scales
Walter Rossing, Biological Farming Systems
Outline
� Landscapes?
� Ecosystem functions / services
� Overview of effects of OA on landscape and biodiversity
� 2 Illustrations of interactions between ecosystem functions
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Landscape
� Definition: Territorial or spatial unit produced through the interaction between human societies and cultures with the natural environment (Wascher, 2000).� Many if not most of the interactions are related to
agriculture
� Inherently multifunctional: integrate various functions demanded by society.
� Classification and study according to these functions.� But: mind the interactions!
Evolution of the notion Landscape
Europe:
� Medieval times: landscape is a region, an area (physical reality)
� 16th century: landscape is an image (paintings)
� 17th century: landscape is an organized whole (science)
� 20th century: landscape is a system (science)
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Landscape as system: Ecosystem Functions
� Regulation functions: maintenance of essential ecological processes and life support systems
� Habitat functions: providing suitable habitat (living space) for wild plant and animal species
� Production functions: provision of natural resources
� Information functions: providing options for cognitive development
Source: R.S. de Groot et al., 2002
Ecosystem Functions: examples
� Regulation functions� E.g. soil retention and fertility, water supply, biological control
� Habitat functions� E.g. refuge function, nursery function
� Production functions� E.g. food, raw materials, genetic resources
� Information functions� E.g. aesthetic information, recreation, cultural & artistic info
Source: R.S. de Groot et al., 2002
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Land use by agriculture: Guerrero Mexico
Land use by agriculture: Guerrero Mexico
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Land use by agriculture: South Africa
Valuation of Ecosystem Functions, Goods & Services
Source: R.S. de Groot et al., 2002
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Environmental impacts of Organic Agriculture (OA)Aspect/IndicatorArea
Genetic diversity; Floral diversity; Faunal diversity; Habitat diversity
Biodiversity
Intensity of use; Efficiency of useEnergy
Carbon dioxide; Nitrous oxide; Methane; Ammonia
Climate and air
Nutrient use and balance; Nitrate leaching; Phosphorus; Pesticides; Pathogens
Ground and surface water
SOM and acidity; Biological activity; Soil Structure; Erosion; Desertification
Soil
Landscape structures and aesthetic valueLandscape
Source: Organic Agriculture. Kristiansen, Taji, Reganold (eds)
Assessment of environmental impacts of OA
RelativeAbsolute
++/B; +?
+?; +/B?; ?; +/B?
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Environmental ImpactAspect/IndicatorArea
Genetic diversity
Floral diversity
Faunal diversity
Habitat diversity
Biodiversity
Intensity of use; Efficiency of useEnergy
Carbon dioxide; Nitrous oxide; Methane; Ammonia
Climate and air
Nutrient use and balance
Nitrate leaching
Phosphorus
Pesticides
Pathogens
Ground and surface water
SOM and acidity
Biological activity
Soil Structure
Erosion
Desertification
Soil
Landscape structures and aesthetic value
Landscape
Source: Organic Agriculture. Kristiansen, Taji, Reganold (eds)
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Conclusions of Environmental Assessment OA
� OA has much potential for better environmental (including landscape) performance than conventional agriculture
� Unfolding depends on motivation of farmers and financial support
� Intensification of organic agriculture is a serious threat to this positive assessment
Limitations of the assessment
� Variation in definition of OA between countries
� Different levels of control of external variation
� Variation in period of study
� Variation in spatial scale
� Variation in measures of biodiversity
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Landscape as system: Ecosystem Functions
� Regulation functions: maintenance of essential ecological processes and life support systems
� Habitat functions: providing suitable habitat (living space) for wild plant and animal species
� Production functions: provision of natural resources
� Information functions: providing options for cognitive development
Source: R.S. de Groot et al., 2002
Illustration 1: Information function
� How can ‘landscape quality’ be measured?
� Legibility (Readability) of the landscape: � Where am I?
� In which place?
� In which time?
� Case study� Comparison of organic farms and conventional farms
in 3 regions in NL: Hendriks and Stobbelaar, 2002
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What can you ‘read’ in this landscape?
Four perspectives to determine the readability of
the landscape
vertical
historiccycli
c
horiz
ontal
Farm image
Regional image
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The better the readability of the landscape,
the higher landscape quality
Diagnosis and development of landscape quality
Reading the landscape, current quality
Examples of goodpractice
Target image Landscape development, future quality
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Readability variables
� 4 Perspectives:� Historical cohesion� Cyclical cohesion� Horizontal cohesion� Vertical cohesion
� 3 Farm areas� Fields� Field Margins� Farm yard
Historical cohesion weak
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Historical cohesion strong
Cyclical cohesion weak
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Cyclical cohesion strong
Horizontal cohesion weak
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Horizontal cohesion strong
Vertical cohesion weak
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Vertical cohesion strong
Conclusions readability project
0255075
100V-field
Ho-field
C-field
Hi-field
V-yard
Ho-yard
C-yard
Hi-yard
V-margin
Ho-margin
C-margin
Hi-margin
Conventional farms
Organic farms
V=Vertical
Ho=Horizontal
C=Cyclic
Hi=Historic
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Conclusions readability project
� Landscape quality can be improved considerably onmany farms
� Readability of organic farms is on average betterthan that of conventional farms
� ‘Readability’ and ‘target image’ are useful conceptsfor measuring and development of the landscape quality ecosystem function
Illustration 2: Production, information & habitat
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Friesian Woodlands
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ReBdesign of the landscape TwijzelBBuitenpost
� NGO Landscape Management Friesland: enhancing connectivity and landscape identity in a rural zone of a few hundred ha.
� Based on rules of thumb.
� Can science add to this process?
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Landscape IMAGES model: approachGoal definition
Formulation of a case specific perception of
sustainability
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Sustainability assessment
Case specific degree of sustainability
Indicator set
Characterization of the state aspired: dimensions and thresholds
System definition
Definition of actual or alternative land use
systems
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Goal definition
Formulation of a case specific perception of
sustainability
Goal definition
Formulation of a case specific perception of
sustainability
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Sustainability assessment
Case specific degree of sustainability
Sustainability assessment
Case specific degree of sustainability
Indicator set
Characterization of the state aspired: dimensions and thresholds
Indicator set
Characterization of the state aspired: dimensions and thresholds
System definition
Definition of actual or alternative land use
systems
System definition
Definition of actual or alternative land use
systems
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Exploring interactions between indicators
Naturevalue
Gross margin
Pareto frontier
Solution space
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ParetoBbased multiBobjective optimization
generateby allocating
landBuse activities
evaluatefor multipleindicators
selectusing nonBweighing
ParetoBbased methods
Naturevalue
Gross marginLandscape generated in the computer
Landscape IMAGES model: approachGoal definition
Formulation of a case specific perception of
sustainability
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Sustainability assessment
Case specific degree of sustainability
Indicator set
Characterization of the state aspired: dimensions and thresholds
System definition
Definition of actual or alternative land use
systems
1
2 34
56
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Goal definition
Formulation of a case specific perception of
sustainability
Goal definition
Formulation of a case specific perception of
sustainability
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Ecosystem modeltoolkit
Expresses system performance in terms of
indicator set
Sustainability assessment
Case specific degree of sustainability
Sustainability assessment
Case specific degree of sustainability
Indicator set
Characterization of the state aspired: dimensions and thresholds
Indicator set
Characterization of the state aspired: dimensions and thresholds
System definition
Definition of actual or alternative land use
systems
System definition
Definition of actual or alternative land use
systems
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22 3344
5566
55
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Indicators: Connectivity
Dispersal range
Largest connected cluster (m)Largest connected cluster (m)
Indicators: Sight lines ~ landscape identity
‘porosity’
Sight range
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Indicators
� Ecology� ↑ connectivity (spatial coherence)
� Landscape quality� ↑ variation in sight lines
� ↓ ‘porosity’ (road to road)
� ↑ ratio in length/width direction hedges (L/T ratio)
� Costs� ↓ addition of new hedges
� ↓ removal of existing hedgerows
� ↓ total length of hedgerows
(↑ maximize, ↓ minimize)
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Landscape IMAGES: maps
Plan of NGO An alternative plan: same hedgerow length and
landscape value as NGO; higher ecological connectivity
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Sight line homogeneity Hedgerows added (km)Spatial cohesion L/T ratio PorosityHedgerow length (km)
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TradeBoff results 7 indicators
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Outline B revisited
� Landscapes?� Define what you mean: spatial + temporal scales
� Ecosystem functions / services� Useful concepts for thinking on landscapeBagriculture
� Overview of effects of OA on landscape and biodiversity� Little studied; data lacking from Southern Hemisphere
� 2 Illustrations of interactions between ecosystem functions� Production, habitat, regulation, information
Thank you for your attention