the role of fire in ecological restoration:

unanswered questions

naomi rea, mulga.data@westnet.com.au

This presentation:

arose from the use of fire for ecological restoration having

brought many different groups or sectors together in a space

where fire promotion overshadows discussion about risks

highlights research areas to inform a judicious role of fire in

ecological restoration

Research that:

resolves uncertainty

clarifies assumptions

leads to unambiguous language

key feature of fire - generally easy to start

training/expertise not required

but shouldn’t detract from fire’s serious nature and impact

whole ecosystems are effected

fire for ecological restoration and Indigenous cultural

burning involves knowledge and understanding (why,

when, where) … … but fire is still a risky business

fine line between destructive and restorative impact

fires are often hard to put out

more country is burnt than often intended

In this situation

critically important that evidence underpins practise

without informed fire management, there may be

counterproductive outcomes

knowledge base is developing

noticeable gaps

opportunity to frame research questions

Observation 1. Using fire as a management tool involves

underlying tensions between:

Bushfire is an EPBC listed ecologically threatening process

versus used as an ecological restoration tool

National policy to decrease Carbon emission versus burning that

accelerates emissions (caveat: small burns can limit larger burns)

Use of fire to control fire

National policy to restore and increase Soil Carbon versus

burning that overall reduces Soil Carbon

Adverse respiratory health problems from smoke versus

accepting health consequences of bushfire

Land managers interest in fire for ecosystem management versus

emergency services interest in fire for fire suppression

Issue 1

As an environmental factor, fire is relatively uncommon -

lightning ignition (albeit more common in lightning prone regions).

Fire has become very much a human activity and

has become relatively common.

Prior to human evolution, fire along with

other stochastic forces (unexpected

disturbances: ie flood, drought, tsunami,

cyclone), was uncommon.

Fire as a human activity is a relatively

recent driver on the evolutionary clock.

As a human activity, fire is now used (or avoided) not so much

to reinstate ‘natural’ fire regimes but:

a) as a management tool and

b) to reinstate Indigenous burning practises

This presentation focusses on a subset of (a) fire as a

management tool: ie

(c) fire as a management tool in ecological restoration:

questions and research that could inform the role and merit

of fire in this situation

Fire as a human activity

Black Friday, January 13, 1939. There were multiple sources of ignition:

Lightning kindled some fires, but most emanated from a register of casual

incendiarists that reads like a roster of rural Australia: settlers, graziers,

prospectors, splitters, mine workers, arsonists, loggers and mill bushmen, hunters

looking to drive game, fishermen hoping to open up the scrub around streams,

foresters unable to contain controlled burns, bush residents seeking to ward off

wildfire by protective fire, travellers and transients of all kinds. Honey gatherers lit

smoking fires. Campers burned to facilitate travel through thick scrub.

Locomotives threw out sparks along their tracks. A jackeroo tossed lighted

matches alongside a track so that his boss would know where he was. Residents

hoping to be hired to fight fires set fires. Possibly a third of the documented fires

had no known cause. A self styled bushman shrugged off the multiple sources by

explaining to a royal commission that “the whole of the Australian race have a

weakness for burning.”

Pyne,S. Burning Bush. A Fire History of Australia. 1991, pg31.

Research Q1:

Background:

There is a great deal of both consistent and contradictory

evidence from paleoecology, palynology, archaeology,

anthropology about the extent and nature of fire in Australia

prior to human records, across recorded Aboriginal occupation

and over 200+ years of European colonization.

Objective:

Collate and summarize the major theories supported by

evidence as a benchmark at this time, and

to inform reasoned debate, action and research needs.

Issue 2

What shapes vegetation types?

vegetation types are shaped by topography, climate,

soil (many references)

these drivers underpin a plant’s essential requirements (water, light, O2, CO2, nutrients, space)

seasonal variation in essential requirements is a stress that limits

productivity and performance

stochastic or unexpected disturbances are not essential (fire, flood, drought, cyclone, tsunami, human activity)

not necessary for plants to grow and reproduce; major disturbances

can plant death, species loss or ecosystem change

Plant growth and survival

Essential and Non-essential Factors

Some plants may have some traits that allow them to withstand some

disturbance some of the time, but this does not mean a plant needs fire

(or other stochastic disturbances) to survive.

Ecosystem change post fire depends on fire timing, intensity,

frequency.

one shift is from fire sensitive to fire prone vegetation

(caveat: careful judicious use of fire can protect fire sensitive vegetation)

Non-essential forces or disturbances can leach a landscape of

essential elements and ‘take an ecosystem back to the starting line’

from where it has to re-establish and recover. This is a difficult

challenge where weeds are present and where the climate has

become less favourable.

Research Q2:

Background:

Fire has become part of some of the Australian landscape

as a result of human activity past and present. With regard

to this situation, there are many generalisations with

underlying assumptions that are open to interpretation.

Objective:

Investigate possible merit, fallacies or risks of

generalizations such as ‘fire is part of the Australian

landscape’ and the ‘bush needs a burn’ and develop

accurate defensible descriptions of specific aspects

of fire and Australia’s environment.

Issue 3

Tolerance vs adaptation

a fire tolerant plant does not necessarily equate with a fire

adapted plant, nor a plant that needs fire

traits may have been selected for, but that may not equate with

saying that a plant needs fire to survive, nor that an ecosystem

needs fire to function

diet analogy – people can tolerate being starved to a certain

extent, but most people do not need to go on a diet

Huon Pine forests (1in 2000 year fire regime) are not adapted to a

very low fire regime they just not able to tolerate fire

Research Q3a:

Background

Plant traits that have enabled a plant to withstand an impact

are not necessarily traits that are adaptations

Objective:

With regard to fire, distinguish between:

– what a plant needs and what it can tolerate

– a plant adaptation versus a plant trait (that enables

tolerance of a stress or disturbance)

– the impact of fire on plant species versus plant

communities versus the whole ecosystem

Epicormic growth

epicormic buds are not necessarily an ‘adaptation’

they are a trait that is a response to any serious stress

its what eucalypts do

Seed Dormancy

is fire or chemicals in smoke necessary to break seed

dormancy or emergence from underground structures?

it is one cue, but there are many other cues for breaking

dormancy of seeds with hard coats:

• alternating temperatures (diurnal variation)

• frost, ice, saturation

• microorganisms causing seed coat decay

• animal or bird foraging, break seed coat

Research Q3b:

Background

Epicormic buds are often regarded as an adaptation to fire.

Some plants are referred to as being adapted to fire because

heat/smoke can break their seed dormancy

Objective:

1) Explore the difference between adaptation and tolerance

using epicormic shooting in eucalypts.

2) Investigate factors that break dormancy in different species

relative importance of fire or smoke as a cue

relative frequency of different factors

frequency of factors vs seed bank viability

consequences of flushing seed bank, possible exhaustion

Issue 4

Terminology

The term ‘adaptation’ illustrates the ambiguity of language and underlying

assumptions and how terms can be misinterpreted.

Fuel

Litter

Both refer to ‘dead and decomposing plant and organic matter’ in

natural environments. Opportunity for new language.

Research Q4:

Background

• Issues around language; misunderstanding, misinterpretation

• Many Indigenous languages, as compared to English, are

more diverse and better describe complexities of the

environment.

Objective

Need to clarify and define terms

Opportunity for new vocab to explain nuances

Issue 5

Coarse particulate organic matter

(colloquially known as fuel or litter)

ameliorates ecosystem temperature

extremes; warm in winter, cool in summer

water retention, carbon and nutrient storage and cycling

prevents leaching and run-off of water, nutrients, carbon

litter load (dwt g m2) is often less than it appears

habitat for micro-organisms, fungi, bacteria, animals and birds

Coarse particulate organic matter - role of biota

Native animals and birds -

reduce litter load through:

foraging and scratching by bush hens, bandicoots, echidna,

wombats, scrub fowl, lyre birds etc that also turns over the soil

facilitating decomposition and recycling of nutrients for plants and

animals to use again

controlling weeds and weed seeds by eating, scratching, trampling

likely break seed dormancy, and facilitate seed germination and

establishment of native plants

wallaby/kangaroo also graze grasses making some places look

like a lawn

Research Q5:

Background

Loss and decline of native animals in Australia.

Dead and decomposing plant material (fuel, litter) generates

concerns and mitigating actions.

Objective

Does absence of biota result in higher litter loads?

What is the role of native animals and birds in terms of:

a) litter loads

b) nutrient cycling

c) seed germination

d) weeds

Could reintroducing native wildlife reduce risk of wildfire?

Issue 6

Soil Carbon

global soil carbon is twice global atmospheric C

small changes in soil carbon flux could impact atmospheric CO2

(Zhaosheng Fan & Chao Liang 2015)

microbial populations in soil and litter drive carbon cycle

todays litter (‘fuel’) will be tomorrows soil

maintaining and increasing soil carbon is a major Government

policy and investment

fire results in carbon emissions and limits carbon entering the soil

if litter can be allowed to decompose, a cooler world

Research Q6:

Background

Fire results in carbon emissions and limits carbon entering

the soil. Todays litter (‘fuel’) will be tomorrows soil … if

allowed to decompose. This promotes a more resilient

healthy ecosystem and a cooler world.

Objective

What are the impacts on soil carbon from burning for

ecological restoration and how is the whole

ecosystem effected?

Summary - risks of using fire in ecological restoration

managing for single species can be problematic as fire does not

discriminate, it is a blunt tool

what helps one species may be detrimental to another

whole ecosystems effected; large ±error possible extinctions

possible counterproductive outcome – weeds proliferate and

environment becomes more flammable, increasing risk of wildfire

fire and inappropriate frequency and intensity can deplete soil

fertility, decrease infiltration and protective plant cover, increase

surface runoff, erosion ecosystem degradation, species loss, more

fire prone environment

the more stress and disturbance from fire, the less chance an

ecosystem can recover slow process of desertification, amplified

by warmer drier climate

eg in dry sclerophyll forest, bark took 15-25yrs to recover to pre-

burn conditions (Tolhurst 1994); tree canopy never fully recovers

(pers.obs.)

Summary - fire for ecological restoration

fire is all about vegetation, however there is a scarcity of plant

ecologists working in this space

Although Australia’s vegetation is shaped by topography, soil,

and climate … fire as a human activity and management tool, has

influenced vegetation in many places and has potential to

become major driver of vegetation change (desirable or

otherwise)

fire as a powerful and blunt instrument with far reaching

consequences could be ‘up the back’ as an option, ‘up front’ or

somewhere between

Summary - Research topics

Test generalisations and underlying assumptions through

rigorous analysis of the literature

Discriminate between essential vs non-essential plant

requirements

Discriminate between adaptation vs tolerance

Fire management to help soil carbon capture and

storage

Expand terminology and articulate accurately