Risk assessment of Australian ecosystems

David Keith & IUCN Ecosystem Red

List Working Group

Status of Australian ecosystems - Why we need to know

• International obligations• Legislative responsibilities

– an informed Australian public

• Evidence-based decision making & priorities – env’t investment, trade-offs

• Responses to ecosystem management

• Horizon scanning

A framework for synthesis- risk assessment of ecosystems

• Red List of Species– International standard for

assessing risks to species– Generality, data-efficient,

effective communication

• No analogue for assessing risks to higher levels of biodiversity

Red List criteria for Species

D. Very small population distribution AND serious plausible threats

C. Small populationAND fragmented/decline/fluctuation

B. Small geographic distributionAND fragmented/decline/fluctuation

A. Decline in # mature individuals over 10 yrs / 3 generations

and / or

and / or

and / or

Critically Endangered

Endangered

Vulnerable

QU

AN

TIT

AT

IVE

TH

RE

SH

OLD

S

“quantitative” categories

“qualitative” categories

Near ThreatenedLeast ConcernData DeficientNot Evaluated

E. Risk of extinction over next 3 gens/100 yrs

and / or

Assessing risks to ecosystemsEcosystem concept (4 defining features, Tansley 1935)

1. Characteristic assemblage of biota

2. Associated physical environment

3. Processes & interactions between components– among biota

– between biota & environment

4. Spatial extent

Risks

Ecosystem collapse- transformation, loss of defining featuresRisk assessment- probability of collapse over a given time frame

Semi-arid rangelands (Westoby et al. 1989) – desertification

Intense sustained herbivore activity destabilises soil surface, degraded soil inhibits recruitment of perennial plants

Transient herbivore activity maintains soil crust & perennial plant cover, limiting soil erosion & degradation

?

Towards a Red List of ecosystems

Assessing Ecosystem Change

Risk model for ecosystems

• threats to defining features (distribution, biota & function)

• multiple mechanisms (causes of threat)

• 4 symptoms (of decline) = 4 criteria

• plus one overarching criterion (probability of collapse)

Threatening processes

Threatening processes

Risk of loss of characteristic

native biota

A Declining distribution

C Environmt’l degradation

D Altered biotic processes

Ecosystem distribution

Ecosystem function

B Small distribution

E Quantitative risk analysis

A. Decline in distribution – criteria & thresholds  A1 A2 A3

Status

Current (last 50 yrs)

Future (next 50 yrs)

Historic (since c. 1750)

CR ≥80% ≥80% ≥90%EN ≥50% ≥50% ≥70%VU ≥30% ≥30% ≥50%NT almost 30% almost 30% almost 50%LC <30% <30% <50%

Change in wetland distribution 1960 – 2000

ContractionExpansion

3

4

1

2

7

510

968

0.5 0 0.5 1 Kilometres

Remained woodland

Woodland to swamp

Remained swamp

Swamp to woodland

10% net increase in distribution (Keith et al. 2010)

Criterion A = Least Concern

C & D: Steps for assessing functional decline

1. Select one/more variables representing ecosystem function(s)

2. Estimate ‘collapsed state’ – what value of the functional variable indicates ecosystem collapse?

3. Estimate initial state – what is the past value of the variable, e.g. 50 yrs ago?

4. Estimate current state – what is the current value of the variable?

5. Calculate range-standardised decline & compare with thresholds

Selecting variables for assessing functional declines (C & D)

Must represent key ecosystem driver or threatening process

• Proximal variables better than indirect ones• Ecosystem-specific variables better than generic ones• Sensitive variables better than insensitive ones• Choice informed by cause/effect process models (cause-effect diagrammatic summaries of ecosystem dynamics)

Selecting functional variables for ecosystem risk assessment

River Red Gum Forests

Mac Nally et al. 2011

S. Cunningham

Salient functional variables• stream flow (criterion C)• foliage cover (criterion D)

Selecting functional variables for ecosystem risk assessment

Coral reefs

Coral reef

Coral diseases

StormsFishing

Polluted runoff

Climate change

Herbivorous fish

Predatory fish

Algae

Water temperature & chemistry

Human population

Coral reef

Coral diseases

StormsFishing

Polluted runoff

Climate change

Herbivorous fish

Predatory fish

Algae

Water temperature & chemistry

Human population

Salient functional variables• sea surface temperature, ocean acidity (criterion C)• coral cover, reef rugosity (criterion D)

Estimating relative severity of functional decline1. Select functional variable (mean ann max river

hgt)

2. Estimate ‘collapse state’ (450-500 cm)

3. Estimate initial state (712 cm)

4. Estimate current state (619 cm)

5. Calculate range-standardised decline

100*(observed)/(collapsed) = 35-44% (past 50 yrs)

0

5

10

15

20

25

30

1960 1970 1980 1990 2000 2010

Year

Mur

ray

Riv

er In

flow

(G

L/yr

)

Max river hgt <400 cm

Max river hgt 500 cm

Max River Hgt >700cm

0

100

200

300

400

500

600

700

800

900

1000

1900 1920 1940 1960 1980 2000

Year

Me

an

ma

xim

um

riv

er

he

igh

t (c

m)

Average max10 yr mean average maxSeries1Series3

Criterion C1 = VULNERABLE

Risk assessment outcomes- level of risk, causes of decline

Risk assessment implicates climate change as greatest threat adaptation strategies

LCEN-CR contracting future distribution LCENENLCLCEN-CR declining bioclimatic habitat suitabilityDDDDDDDDDD

A

B

C

D

E

What can risk assessment tell us about the status of biodiversity?

Madagascan Tapia Forest: EN

Venezuelan Tepui: LC

Murray-Darling Wetlands: EN-CR

European Reedbeds: VU

Murray River Red Gum Forests: VU

Coolibah-Blackbox WL: EN

New Zealand Granite Gravel Fields: LC

Cape Flats Fynbos: CRAlaskan Kelp Forests: EN-CR

Caribbean Reefs: EN-CR

Sth Aust Seagrass Meadows: EN Coorong Lagoons: CR

Data requirements for ecosystem risk assessment

Spatial data• Ecosystem distribution (derivatives of landcover types, soil

types, terrain)

• Change in distribution & function (time series of landcover, biomass, hydrology, productivity, disturbance metrics)

Plot/site data• Species composition (ecosystem description, classification)

• Ecosystem processes (time series of species composition, abundance, biomass, productivity, hydrology, edaphic, climate)

Better environmental reporting for Australian ecosystems

ACEAS working group- risk assessment of Australian ecosystems

Objectives• Train Aust & NZ practitioners in Red List

assessment methods• Review current listing procedures for

ecosystems/communities cf. new international standard

• Review data requirements for risk assessment and capacity of TERN to provide (LTERN, AusCover)

• Develop detailed risk assessments for selected Aust & NZ ecosystems

Thank you