Framework for assessing and reporting resilience of native vegetation

Richard Thackway

Lecture presented as part of the Fenner School of Environment and Society, ANU’s undergraduate course, ENVS3041 Managing Forested Landscapes

8 March 2017

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

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)

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

Change over space

Thackway & Lesslie (2008) Environmental Management, 42,

572-90

NB: Input dataset biophysical naturalness reclassified using VAST framework

/ replaced

/ unmodified

VAST 2009

Native

How to account for changes in native veg type, extent and condition?

LMP deliberately &/or unintentionally do this by:• Modifying • Removing and replacing• Enhancing• Restoring• Maintaining• Improving

*

* Natural disturbances

Function

Structure & Composition

LMP = land management practices

Tracking change and trends based assessing effects of land management regimes

Effects of regimes on criteria & indicators of function, structure and composition

Examples

No active interventions Biodiversity protection, minimal useHarvest products Biomass, fibre, flowers, fruit and nutsEnhance or improve Rehydrate soils, control invasive

species, reestablish a fire regime, seed hays

Extirpate or remove Overgrazing, intensive cropping, pasture improvement, removal of fire regime, draining wetlands

Reconstruct Revegetate, rehydrate soils, stabilize soil

Thackway and Freudenberger (2016)

A framework that is relevant to all terrestrial ecosystems and their

modification states

Source: http://www.headlinesciencenow.com/2013/11/29/cracking-chicken-egg-mystery/

Response variables (effects)

Management regimes

VAST I: Unmodified /residual native

Photographs: Richard Thackway & Ross Peacock

VAST II: Modified native

Photographs: Richard Thackway

VAST III: Transformed native

Photographs: Richard Thackway

VAST IV: Replaced & adventive

Photograph: Richard Thackway

VAST V: Replaced & managed

Photographs: Richard Thackway

VAST VI: Replaced & removed

Photographs: Richard Thackway

A framework for assessing and reporting vegetation resilience

(space and time)

Understanding ecosystem change over 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

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

t2t1t3

Creating systematic and comprehensive chronology to assess where, when and how landscapes are transformed relative to a reference

Composition Structure

LU = Land Use, LMP = Land Management Practices

VAST Diagnostic attributes

LU & LMPYear

Time

Function

Reference Reference Reference

Components (3)

Function Regenerati

ve capacity

Vegetation structure

Species Compositi

on

Components (3)

Criteria(10)

Function Regenerati

ve capacity

Fire regime

Soil hydrology

Soil physical state

Soil nutrient state

Soil biological state

Reproductive potential

Vegetation structure

Overstorey structure

Understorey structure

Species Compositi

on

Overstorey composition

Understorey composition

Components (3)

Criteria(10)

Description of loss or gain relative to pre settlement indicator reference state (22)

Function Regenerati

ve 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

1

3

10

22

Diag

nosti

catt

ribut

es

VegetationTransformation

score

Attrib

ute

grou

ps

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

VAST-2 – benchmark scoring of the effects of use and management of native veg (indicators) over time

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

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

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

capacityFunction

Natural disturbance

Change in the area /size of eventsChange in the number of events

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

Case study 1Phillip Island, South Pacific

Phillip Island

Google earth

Photograph: Peter Coyne

1740

1906

Phillip Island, South Pacific

Photograph: State Library NSW: JW Beattie

By 1860 already denuded (Removed and replaced: VAST VI)

Reference (Unmodified: VAST I)

Pine – Hardwood Subtropical Rainforest

1981

2008

Photographs: Peter Coyne

(Adventive: VAST IV)

(Adventive: VAST IV)

year

scor

e %

Pine – Hardwood Subtropical Rainforest, Phillip Island, Sth Pacific

Pigs released

Uninhabited island

Pigs died out

Goats and rabbits released

Goats died out

Rabbits eradicated

Rabbit control

commenced

Commenced passive & active

restoration. Minimal ecological

monitoring

Case study 2Bridge Hill Ridge, Myall Lakes,

NSW

Sand mining path

Bridge Hill Ridge

Sydney

Newcastle

Smiths Lake

Restoration following mineral sand mining

Topsoil briefly stockpiled <10 days

Timber harvested and remaining trees and vegetation removed

1974 (0 years old)

Photographs: Barry Fox

(Removed and replaced: VAST VI)

Sand sprayed and dried and re-shaped as a contoured

dune

Sandmining Dredge

OriginalEucalypt open forest

DredgePond

Smiths Lake

Dredge Pond

1974 (0 years old)

Photographs: Barry Fox

(Removed and replaced: VAST VI)

1974-75 (0-6 months old)

Topsoil spread over reshaped sand dune

Sorghum cover crop planted

1974 (One month old) 1975 (< 6 months old)

Photograph: Barry Fox

(Removed and replaced: VAST VI)

(Removed and managed: VAST V)

2014 (39 years later)

Photographs: Richard Thackway(Unmodified: VAST II)

Function (Regenerative capacity)Criteria

Criteria

Vegetation structure

Criteria

Species composition

Predictions of mature forest (Bunning’s Enquiry 1974)*

* 50 yrs 2035, 80 yrs 2055, 100 yrs 2074

• 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: 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

Agro-climatic regions

Peer reviewed sites

Applications of the framework

Tran

sfor

mat

ion

scor

e

Years

1800

2016

Reference

Relevance to developing scenarios for future landscape transformation

Modified

Transformed

Replaced/ managed

Residual

Replaced/adventive

VAST Classes

1850 19501900 2000 2050 2100Replaced/ removed

Baseline

Classes can be modelled as extent and condition

Extent native

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