A framework for assessing and reporting resilience of native vegetation

A framework for assessing and reporting resilience of native vegetation

Richard Thackway

Lecture presented as part of the Managing Forested Landscapes an undergraduate course , ENVS3041 Class number 4029.

Fenner School of Environment and Society, ANU

2 March 2016

Outline

• Concepts and definitions• Why & how land managers change their landscapes• A standardised system for assessing and reporting resilience • The VAST methodology site and landscape • Case studies - Cumberland State Forest, Sydney• Lessons • Conclusions

Goals of land managers

Changes in ecological function

Values and decisions matrix:• Social• Economic• Environmental

Intensification

Degradation?

Goals of land managers

Changes in ecological function

Values and decisions matrix:• Social• Economic• Environmental

Extensification

Restoration

Regulation of hydrological regime Generation of food and fibre Regulation of climate / microclimate Generation of raw materials Recycling of organic matter Creating and regulating habitats Controlling reproduction and dispersal

Changing ecological function to derive multiple benefits (ecosystem services)

A framework for assessing and reporting vegetation resilience

Definitions

• Change in a plant community type due to effects of land management practices:

– Structure

– Composition

– Regenerative capacity• Resilience = capacity of an plant community to recover toward

a reference state following change/s in land management

• Transformation = changes to vegetation condition over time• Condition, resilience and transformation are assessed relative

to fully natural a reference state

Vegetation condition

Land managers affect native veg condition in space and over time

Process: Land managers use land management practices (LMP) to influence ecological function at sites and the landscape by:• Modifying • Removing and replacing• Enhancing• Restoring• Maintaining• Improving

Purpose/s:To achieve the desired mix of ecosystem services (space & time)

1925

Occupation

Relaxation

Anthropogenic change

Net benefit

time

1900 2025 1950

Reference

chan

ge in

veg

etati

on in

dica

tor o

r ind

ex

1850 1875 1975 2000

VAST classes

A model of ecosystem change (causes & effects)

Variable date?reference state = Unmodified

Understanding states and transitions(space and time)

Indigenous land management

First explorers

Grazing

Degr

ee o

f m

odifi

catio

n

Logging

Cropping

Site 1

Site 2

Site 3

Time

Reference state

Long term rainfall

Long term disturbance e.g. wildfire, cyclones

Revegetation

VAST states The same ecosystem e.g. eucalypt open forest with different management histories

t2t1t3

Land managers change 10 key criteria affecting the resilience of a plant community

Soil

Vegetation

Regenerative capacity/ function

Vegetation structure & Species composition

1. Soil hydrological status2. Soil physical status3. Soil chemical status4. Soil biological status5. Fire regime6. Reproductive potential7. Overstorey structure8. Understorey structure9. Overstorey composition10. Understorey composition

VAST = Vegetation Assets States and Transitions NVIS = National Vegetation Information System

VIVIVIIIIII0

Native vegetationcover

Non-native vegetationcover

Increasing modification caused by use and management

Transitions = trend

Vegetation thresholds

Reference for each veg type (NVIS)

A framework for assessing & reporting changes in plant communities

Condition states

Residual or unmodified

Naturally bare

Modified Transformed Replaced -Adventive

Replaced - managed

Replaced - removed

Thackway & Lesslie (2008) Environmental Management, 42, 572-90

Diagnostic attributes of VAST states:• Vegetation structure• Species composition• Regenerative capacity

NVIS

Condition of plant communities – a snap shot

Thackway & Lesslie (2008) Environmental Management, 42,

572-90

NB: Input dataset biophysical naturalness reclassified using VAST framework

/ replaced

/ unmodified

VAST 2009

Native

Aggregate reporting using a hierarchy of regions

1) Agro-climatic, 2) IBRA, 3) IBRA sub-regions

Aggregate reporting of classes of resilience using agro-climatic regions

Aggregate reporting of classes of landscape alteration levels

Synthesising information using a hierarchy

• Level 1: Scores over time• Level 2: Components• Level 3: Criteria• Level 4: Indicators• Level 5: Field measures/observations (Direct) and Expert /inference

models (Indirect)

Components (Level 2)

Criteria(Level 3)

Description of loss or gain relative to pre settlement indicator reference state (Level 4)

Regenerative

capacity

Fire regime Change in the area /size of fire foot prints Change in the number of fire starts

Soil hydrology Change in the soil surface water availabilityChange in the ground water availability

Soil physical state

Change in the depth of the A horizon Change in soil structure.

Soil nutrient state

Nutrient stress – rundown (deficiency) relative to soil fertility Nutrient stress – excess (toxicity) relative to soil fertility

Soil biological state

Change in the recyclers responsible for maintaining soil porosity and nutrient recycling Change in surface organic matter, soil crusts

Reproductive potential

Change in the reproductive potential of overstorey structuring species Change in the reproductive potential of understorey structuring species

Vegetation structure

Overstorey structure

Change in the overstorey top height (mean) of the plant community Change in the overstorey foliage projective cover (mean) of the plant community Change in the overstorey structural diversity (i.e. a diversity of age classes) of the stand

Understorey structure

Change in the understorey top height (mean) of the plant community Change in the understorey ground cover (mean) of the plant community Change in the understorey structural diversity (i.e. a diversity of age classes) of the plant

Species Compositi

on

Overstorey composition

Change in the densities of overstorey species functional groups Change in no.s of indigenous overstorey species relative to the number of exotic species

Understorey composition

Change in the densities of understorey species functional groups Change in no.s of indigenous understorey species relative to the number of exotic species

Generate total indices for ‘transformation site’ for each year of the historical record. Validate using Expert Knowledge

• Compile and collate effects of land management on criteria (10) and

indicators (22) over time. • Evaluate impacts on the plant

community over time

Transformation site• Compile and collate effects of

land management on criteria (10) and indicators (22)

Reference state/sites

Score all 22 indicators for ‘transformation site’ relative to the ‘reference site’. 0 = major change; 1 = no change

Derive weighted indices for the ‘transformation site’ i.e. regenerative capacity (55%), vegetation structure (27%) and species composition (18%)

by adding predefined indicators

General process for tracking change over time using the VAST-2 system

Case studies VAST-2Cumberland State Forest, Sydney

Cumberland State Forest, Sydney

Cumberland State Forest, Sydney

Field transects to survey of the overstorey and understorey

T1

T2

Site level

On-ground field survey 2012

Transect 1Cumberland SF, ex-comp 8b, 9a, 9b.Regrowth forest

StructureComposition Function

Transect 2Cumberland SF, ex-comp 3a, 7a, 7b, 7c.Repurposed arboretum

On-ground field survey 2012

Cumberland State Forest 1941-2012

Red boundary shows main compartments that were cleared as per the 1943 aerial photograph. This area was fully planted out around 1944 as part of the arboretum. Except for regrowth forests: i.e. compartments 8a, 9a, 9b and 10b

T2

Transect 2 = T2

Compartments

1941

T2

1943

T2

1951

T2

1978

T2

1982

T2

1984

T2

1999

T2

2011

T2

2012

T2

NSW, SB Bioregion, Cumberland SF, ex-comp 3a, 7a, 7b, 7c Vegetation structure

Indicators:#13: Height#14: Foliage cover#15: Age structure

Indicators:#16: Height#17: Foliage cover#18: Age structure

Criteria #7

Criteria #8

NSW, SB Bioregion, Cumberland SF, Transect 2 (ex-comp 3a, 7a, 7b, 7c)Function – Regenerative capacity

Criteria #1 Criteria #2

Criteria #3 Criteria #4

NSW, SB Bioregion, Cumberland SF, Transect 2 (ex-comp 3a, 7a, 7b, 7c)Function – Regenerative capacity

Criteria #5 Criteria #6

NSW, SB Bioregion, Cumberland SF, Transect 2 (ex-comp 3a, 7a, 7b, 7c)Species composition

Criteria #9

Criteria #10

1

3

10

22

Com

pone

nts

(3)

VegetationTransformation

Score (1)

Crite

ria(1

0)

VegetationStructure

(27%)

Overstorey

(3)

Understorey

(3)

SpeciesComposition

(18%)

(2)

UnderstoreyOverstorey

(2)

RegenerativeCapacity

(55%)

Fire

(2)

Reprodpotent

(2)

Soil

Hydrology

(2)

Biology

(2)

Nutrients

(2)

Structure

(2)Indicators

(22)

Synthesisng the effects of land management on indicators over time

Level

1

2

3

4

Count

NSW, SB Bioregion, Cumberland SF, Transect 2 (ex-comp 3a, 7a, 7b, 7c)Reference pre-European: Sydney Blue Gum High Forest

Commenced managing area for recreation. Weed control. Arboretum abandoned

Cleared & sown to improved pasture for grazing & orchard

Commenced grazing native pastures

Indigenous people manage the area

Grazed area gazetted as State Forest, commenced planting arboretum

Area logged for building houses and fences

Commenced managing area as a future production forest. Weed control

Explorers traverse the area and site selected

Ceased grazing. Area purchased as a future working forest

Modified

Transformed

Replaced/ managed or removed

Residual

Replaced /adventive

VAST

VAST Unmodified

Commenced managing area primarily for recreation

Ceased grazing. Purchased & declared as a State forest

Site fenced. Commenced continuous stocking with cattle

Commenced grazing cattle

Indigenous people manage the area

Cleared and commenced regrowing native forest as a future forest production

Tree cover thinned for cattle grazing

Initiated 1st hazard reduction burn

Trees logged for housing, fences & fire wood

NSW, SB Bioregion, Cumberland SF, Transect 1 (ex-comp 8b, 9a, 9b) Reference pre-European: Sydney Blue Gum High Forest

• Network of collaborators• Ecologists, land managers, academics, research scientists,

environmental historians• Inputs

• Reference state • Historical record of land use & Land management practices• Historical record of major natural events e.g. droughts, fires, floods,

cyclones, average rainfall 1900-2012• Observed interactions e.g. rabbits, sheep and drought• Observations and quantitative measures of effects

• Include written, oral, artistic, photographic and remote sensing

Lessons: Resources needed at site level

Lessons: site vs landscape

1. Constrain assessments to soil landscape units because this approximates to land manager’s

2. Must account for major natural events e.g. flood, fire, cyclone3. Remote sensing is only part of the solution –

a) Some measures of remote sensing e.g. greenness of crown health may not be directly related to vegetation condition

4. Tracking outcomes of management interventions a) Must collect on-ground data and have a model for linking change to datasets

derived from remote sensing

Lessons: What is the baseline?

Zero/constant baseline (e.g. environmental planting)

A measure or estimate (red line) that would have occurred in the absence of an activity/intervention e.g.

Resp

onse

va

riabl

e/s

Time

Start ofactivity/

intervention

Time

Varying baseline (e.g. environmental watering)

Resp

onse

va

riabl

e/s

Single intervention & climatic variability

BaselineResponse to activity/ intervention

Indicator 13: Overstorey height

Indicator 4: ground water

Lessons: Importance of dynamics

Assume rainfall is main driver of natural system dynamics• Period 1900 - 2013• Average seasonal rainfall (summer, autumn, …)• Rainfall anomaly is calculated above and below the mean• Two year running trend line fitted

Seasonal rainfall anomaly (Lat -32.404, Long 152.496)

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-2-1.5

-1-0.5

00.5

11.5

22.5

Spring

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-3-2-1012345

Winter

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Autumn

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-2-1.5

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22.5

3

Summer

Source: BOM

Conclusions

• A framework that helps decision makers assess and report change at sites and landscapes due to human management and natural drivers

• A tool (i.e. VAST) for assisting in reporting on the current status of Australia’s vegetation types - used in– National State of the Environment Report (2011)

• An accounting tool (VAST-2) for reporting change and trend in the transformation of vegetation types at sites - used in– National State of the Forests Report (2013) – Regional Environmental Accounts (Wentworth Group of Concerned

Scientists 2015)

More info & Acknowledgements

More informationhttp://www.vasttransformations.com/http://portal.tern.org.au/searchhttp://aceas-data.science.uq.edu.au/portal/

Acknowledgements• Many public and private land managers, land management agencies, consultants

and researchers have assisted in the development of VAST & VAST-2