March 1999
Forest Ecosystem Classification and Mapping for the Hunter Sub-Region in the Lower North East Comprehensive Regional Assessment
Lower North East
Comprehensive Regional Assessment
A project undertaken for
the Joint Commonwealth NSW Regional Forest Agreement Steering Committee
as part of the
NSW Comprehensive Regional Assessments
project number NL 10/EH and NL 02/EH
March 1999
For more information and for information on access to data contact the:
Resource and Conservation Division, Department of Urban Affairs and Planning
GPO Box 3927
SYDNEY NSW 2001
Phone: (02) 9228 3166
Fax: (02) 9228 4967
Forests Taskforce, Department of the Prime Minister and Cabinet
3-5 National Circuit
BARTON ACT 2600
Phone: 1800 650 983
Fax: (02) 6271 5511
© Crown copyright May 1999
ISBN 1 74029 079 8
This project has been jointly funded by the New South Wales and Commonwealth Governments. The work undertaken within this project has been managed by the joint NSW / Commonwealth CRA/RFA Steering Committee which includes representatives from the NSW and Commonwealth Governments and stakeholder groups.
The project has been overseen and the methodology has been developed through the Environment and Heritage Technical Committee which includes representatives from the NSW and Commonwealth Governments and stakeholder groups.
Acknowledgments
This project has been undertaken by the CRA Unit of Sydney Zone NPWS:
Daniel Connolly (Project management/Ecosystem Classification and Modelling)
Jeffrey Pickthall, Jedda Lemmon and Chris Pennay (GIS Data Management and Field Survey)
Steve Bell, Robert Payne and David Thomas were consultant botanists and provided personal data
Leander Wiseman (survey planning and analysis)
State Forests of NSW provided flora data for the Morriset Management Area
The advice, support and direction of David Keith and Michael Bedward made this project possible.
Disclaimer
While every reasonable effort has been made to ensure that this document is correct at the time of printing, the State of New South Wales, its agents and employees, and the Commonwealth of Australia, its agents and employees, do not assume any responsibility and shall have no liability, consequential or otherwise, of any kind, arising from the use of or reliance on any of the information contained in this document.
May 1999 Forest Ecosystem Classification and Mapping for the Hunter Sub-Region
1. Introduction 1
1.1 Comprehensive Regional Assessment 1
1.2 Approach 2
1.3 Study Area 2
2. Methods 6
2.1 Vegetation Sampling 6
2.2 Vegetation Data Analysis 9
2.3 Descriptive Techniques 10
2.4 Spatial Data 10
2.5 Spatial Modelling 12
2.6 Map Compilation 13
2.7 Map Validation 13
2.8 Comparison of Ecosystems North and South of the Hunter River 13
3. Results 15
3.1 Collation of Existing Survey Data 15
3.2 New Survey Data 15
3.3 Forest Ecosystem Classification 15
3.4 Forest Ecosystem Map 19
3.5 Map Validation 19
3.6 Ecosystem Comparison North and South of the Hunter River 21
4. ACHIEVEMENTS 22
4.1 Future Work 22
5. references 23
Maps
Map 1: Hunter Sub-Region Study Area 3
Map 2: Location of Floristic Sites in the Hunter Sub-Region 15
Map 3: Key Undersampled Strata in the Hunter Sub-Region 16
Tables
Table 2.1: Relative Abundance Conversion Scores 5
Table 2.2: Vegetation Data Sets 6
Table 2.3: Environmental Stratification Scheme 7
Table 2.4: Definitions of Diagnostic Species 9
Table 2.5: Spatial Data Layers Used in Modelling 10-11
Appendices
Appendix 1: Summary of Sites Occurring in Each Strata 23
Appendix 2: Forest Ecosystem Profiles 33
Appendix 3: Area of Forest Ecosystems 53
Appendix 4: Comparison of Forest Ecosystems North and South of the Hunter 57
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May 1999 Forest Ecosystem Classification and Mapping for the Hunter Sub-Region
This report describes a project undertaken as part of the comprehensive regional assessments of forests in New South Wales. The comprehensive regional assessments (CRAs) provide the scientific basis on which the State and Commonwealth Governments will sign regional forest agreements (RFAs) for major forest areas of New South Wales. These agreements will determine the future of these forests, providing a balance between conservation and ecologically sustainable use of forest resources.
Project Objectives
This report was undertaken to classify and map forest ecosystems for the Hunter Sub Region within the Lower North East, consistent with specifications of the Joint ANZECC/MCFFA National Forest Policy Statement Implementation Sub-committee (JANIS 1997). Forest ecosystems are the primary surrogates for biodiversity used in CRAs.
The scope of this work, as approved by the Environment and Heritage Technical Committee(EHTC), was to ‘provide a map of the distribution of forest ecosystems occurring across all land tenures within the Lower North East CRA south of the Hunter River’.
Methods
To achieve this end, the project provided for the collection of new field data, compilation of existing data, and the development of a system of classification based on the multivariate analysis of field data. It was recognised by the EHTC that data standards were substantially poorer within the Hunter sub region and that the work developed for this project represented an initial classification system. Seventy-one forest ecosystems were classified and mapped in the Hunter Sub region, including 58 forests dominated by Eucalypts, Angophoras or Syncarpia, four rainforests, seven shrublands and heathlands, and two wetland/swamp ecosystems. Ecosystems were mapped using a hybrid decision tree model/expert system. The model related the occurrence of ecosystems to spatial patterns in mapped environmental variables (parent material, terrain and climate). The resulting map of pre-1750 ecosystems was cut using a 1990 Landsat coverage of extant native vegetation cover to derive extant distributions of forest ecosystems.
Key Results and products
It is anticipated that a new classification system which integrates new field data collected for this project and that of the Lower Hunter and Central Coast Biodiversity Program, will substantially improve upon the work completed here. A revised map and classification definition is expected to be available in late 1999.
The current forest ecosystem map for the Hunter Sub Region is available under licence from the NSW National Parks and Wildlife Service.
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March 1999 Forest Ecosystem Classification and Mapping for the Hunter Sub-Region
1. Introduction
1.1 Comprehensive Regional Assessment
As part of the Regional Forest Agreement (RFA) process, a Comprehensive Regional Assessment (CRA) was carried out to evaluate the economic, social, cultural, environmental and heritage values of the Lower North East region. The CRA provided scientific information needed to develop a comprehensive, adequate and representative (CAR) forest reserve system, the establishment of which is an agreed outcome of RFAs and a commitment of the National Forest Policy Statement (Commonwealth of Australia 1992). Studies carried out under the CRA are intended to refine the results of preliminary studies carried out as part of an Interim Forest Assessment Process (IFA). Regional Forest Agreements will also establish a regime of Ecologically Sustainable Forest Management for all forest tenures in New South Wales, as well as a framework for agreed social and economic outcomes on forest use.
Components of CRAs involving environmental and heritage values including biodiversity are overseen in New South Wales by the Environment and Heritage Technical Committee. The conservation status of biodiversity will be assessed against conservation criteria at several agreed levels including ecosystems, species, wilderness and old growth (JANIS 1997).
The conservation criteria followed in New South Wales CRAs were defined in general terms by JANIS (1997). These criteria recognise biodiversity as a highly complex system of living things incorporating variation at the genetic, species and ecosystem levels (Commonwealth of Australia 1995). Given the logistical difficulty of surveying and assessing representation of all elements of biodiversity, maps of species assemblages are widely recognised in conservation biology as potential ‘surrogates’ or ‘coarse filters’ for biodiversity.
JANIS (1997) identified ‘Forest Ecosystems’ as the primary surrogate for biodiversity in CRAs. Forest Ecosystems were therefore used as a basis for the assessments of biodiversity. For the development of a CAR reserve system in CRAs, JANIS (1997) established the following guidelines for representation of Forest Ecosystems in reserves:
· 15% of the pre-1750 distribution of each Forest Ecosystem, with flexibility considerations applied;
· 60% of remaining extent of vulnerable Forest Ecosystems; and
· all remaining occurrences of rare and endangered Forest Ecosystems reserved or protected by other means as far as practicable.
JANIS (1997) defined Forest Ecosystems and offered advice for application of Forest Ecosystem mapping as a surrogate for biodiversity in CRAs as follows:
A Forest Ecosystem is ‘an indigenous ecosystem with an overstorey of trees that are greater than 20% canopy cover. These ecosystems should normally be discriminated at a resolution requiring a map-standard scale of 1:100000. Preferably these units should be defined in terms of floristic composition in combination with substrate and position within the landscape.’
The aim of this project was to classify and map the distribution of forest ecosystems in the Hunter sub-region within the Lower North East CRA.
1.2 Approach
It was originally envisaged that a seamless forest ecosystem map could be developed over the entire Lower North East region using a consistent methodology. However, given the size of the region (over four million hectares) large variations in the quality of existing information and ecological characteristics were apparent. Separate mapping programs were thus required for the Hunter sub-region and Northern Tablelands in order to complete the data requirements for the North Coast RFAs within the timeframe.
Forest Ecosystem derivation for the area north of the Hunter River sought to integrate the use of floristic site data with research note 17 (SFNSW) vegetation mapping. It was recognised that the Hunter sub-region of the Lower North East Region would require an alternative approach given that less than 8% of the sub region was covered by mapping of this type. Options for the classification of forest ecosystems were discussed at a forest ecosystem workshop convened by RACAC on 17-18 July, 1997. The workshop concluded that the use of full floristic plot data should underpin the identification of all forest ecosystems.
As a result this project (as approved by the Environment and Heritage Technical Committee) was designed to undertake the following tasks for the development of a forest ecosystem map for the Hunter sub-region:
· collate all available floristic site data;
· complete new survey work in unsampled environments;
· derive forest ecosystems using statistical agglomeration techniques;
· extrapolate the derived ecosystems across all land tenures across the sub region;
· produce a map and report which identifies the variation and location of vegetation communities across the sub region;
· correlate the mapped communities to those that have been derived in the area north of the Hunter River; and,
· estimate the distribution of pre 1750 ecosystems.
1.3 Study Area
The Hunter sub-region forms a unique bioregion within the Lower North East CRA. The area is characterised by heavily dissected sandstone plateaux and large flat coastal plains and valleys.
The area within the CRA boundary encompasses almost one million hectares of forest land that extends north from the Hawkesbury River to the Hunter River (Figure 1). The Colo River and the Wollemi National Park represent the western extent of the sub-region. The coastal plains from Gosford to Port Stephens form the eastern limit. It should be noted that a study area slightly larger than that of the RFA boundary was used in order to maximise the use of existing site data in poorly sampled areas of Wollemi National Park.
The land uses are dominated by a rapidly expanding urban environment along the eastern coastal plains in the areas of Newcastle, Wyong, Lake Macquarie, Gosford and Port Stephens. Large coal mining activities predominate across the Hunter Valley. The Eastern Ranges remain available for forestry activities in the SFNSW Morriset Management Area. Large areas of the dissected Sandstone plateaux are dedicated conservation reserves in the National Parks estate.
Map 1: Hunter Sub-Region Study Area
2. Methods
2.1 Vegetation Sampling
2.1.1 Data Audit
An audit of all systematic vegetation survey data was undertaken. Systematic vegetation survey sites conformed to the following characteristics:
· a fixed plot size within which an inventory of all vascular plant species are recorded;
· a measure of relative abundance for each species is recorded at each site; and,
· an accurate location reference (Australian Map Grid) to within 100 metres.
A total of 997 systematic vegetation sites were available for use in this project. Most sites have been extracted from systematic surveys completed within existing conservation reserves and state forests over the last 10 years. More recent regional surveys have provided systematic data across a range of different tenures (NEFBS 1992). The source of all site data used is shown in Table 1.1. All site floristics and attribute data (where collected) are now stored in the NPWS Flora Survey database.
Modifications to the existing site data were limited to a taxonomic review and a conversion of relative abundance scores used by Thomas (1998) to a six point Braun-Blanquet index. Table 1.2 provides the conversion table for these 58 sites.
Table 2.1: Relative Abundance Conversion Scores
Code / Relative Abundance / Braun-Blanquet ScoreV: Very common / very common, usually single spp. dominant / 4
C: Common / common, dominance is shared by 2 to 3 other spp / 3
F: Frequent / frequent, a spp not sharing dominance but remains significant to the composition of the site / 1 or 3 depending on spp.
O: Occasional / occasional occurrence / 1 or 2 depending on spp.
R: Rare / rare, individuals infrequently seen, low count and crown cover / 1 or 2 depending on spp.
No amendments were made to data based on variations in plot size. Preliminary analyses by Keith and Bedward (1998) using vegetation data from the Eden region found that cluster analyses was not sensitive to variations in sample size between 0.04 and 0.1 hectare.
Species taxonomy from each site was standardised to Harden (1993) except where obvious taxonomic changes were apparent. Sub species and variations were included except for those species where such information has been inconsistently collected or for species which have been subject to recent taxonomic revisions. The review ensured that a commensurate taxonomy could be used to compare more recent survey data to that collected over 10 years ago.