What is a bioregion?
Bioregions are relatively large land areas characterised by broad, landscape-scale natural features and environmental processes that influence the functions of entire ecosystems. They capture the large-scale geophysical patterns across Australia. These patterns in the landscape are linked to fauna and flora assemblages and processes at the ecosystem scale, thus providing a useful means for simplifying and reporting on more complex patterns of biodiversity.
Following the trend of governments throughout Australia, the NPWS has adopted a bioregional approach to conserving much of our biodiversity, in response to the need to work with large geographic scales and biological cycles to plan and achieve biodiversity conservation.
Planning for biodiversity at this scale recognises the significance of these natural processes and gives us the greatest opportunity to conserve biodiversity in sufficient numbers and distribution to maximise its chance of long-term survival.
Biodiversity is influenced by but does not recognise administrative boundaries, which is another reason to use a bioregional approach to assess all land across the region.
Subregions, as described by Morgan and Terrey (1992), are 'based on finer differences in geology, vegetation and other biophysical attributes and are the basis for determining the major regional ecosystems'. The subregions that make up each of the bioregions are useful tools in regional conservation planning and in the development of a conservation reserve system that, if it is to be representative of the natural environment, 'must contain viable areas of the major ecosystems of each natural region' (Morgan and Terrey (1992)).
The bioregional and subregional framework
It became apparent in the early 1990s that administrative regions were no longer a satisfactory basis for conservation assessment and planning (Dick 2000). Consequently, the mapping of the bioregions of Australia was undertaken by the Federal Government in cooperation with State and territory conservation agencies to provide a consistent and robust framework for biodiversity assessment and planning.
The result of this Australia-wide mapping exercise was the production of the Interim Biogeographic Regionalisation of Australia or IBRA (Thackway and Cresswell 1995), a system that divides Australia into bioregions on the basis of their dominant landscape-scale attributes. IBRA was developed as a framework primarily to identify deficiencies in the Australian network of protected areas and to set priorities for further enhancing the reserve system (Thackway and Cresswell 1995).
The term 'interim' is retained in the IBRA title because the bioregions are periodically updated as new or more reliable information comes to hand from a range of biological and environmental surveys (Environment Australia 2000) designed to refine bioregional boundaries. At the time of writing, IBRA Version 5.1 contained the most recent updates.
Across Australia some 130 biogeographic regions had already been identified but there had been little communication or congruency across State and territory boundaries about these regions. The use of datasets and environmental information including climate, lithology, geology, landform, vegetation, flora and fauna, land use and other attributes provided the means of rationalising these 130 regions into 80 biogeographic regions, which were then further refined into the 85 bioregions recognised in Australia today (Thackway and Cresswell 1995, Environment Australia 2000). Of these 85 bioregions, 17 are found in NSW. Two lie wholly within the NSW boundary, while the other 15 are shared with bordering States - Victoria, South Australia and Queensland.
The description of IBRA regions according to their geography and ecology (NSW NPWS 1999a) are, however, more relevant to environmental management than administrative boundaries (such as State borders), which are unrelated to the physical attributes of the Australian landscape. The IBRA bioregions therefore provide a logical and functional framework for conservation management, land use and planning throughout Australia.
Throughout Australia bioregions have been further divided into subregions or provinces. Subregions are based on finer differences in biophysical attributes including geology and vegetation (Morgan and Terrey 1992) and because they provide more detailed information about the landscape they can be used for finer scale planning.
Just as the bioregions vary in size, with larger regions, mainly those in arid or semi-arid climates, reflecting less diverse terrain (Thackway and Cresswell 1995), the size, and therefore the number, of subregions found in each bioregion also varies.
To make decisions about biodiversity we need to understand where species occur, the habitats they occur in and the ecological processes that drive those habitats and larger groupings of communities. Bioregional assessments have occurred only over the last 6 years in NSW, and our bioregional information base is variable but dynamic.
Information on biodiversity has been, and will continue to be, gathered at many levels of detail as part of bioregional or statewide assessments or will emerge as a result of more detailed management of individual areas, ecosystems or species.
We can begin to describe and report on the condition of biodiversity in the NSW bioregions although not always as precisely as is needed for detailed land management decisions. This document provides some of the more detailed information on biodiversity for each bioregion at the same time as using less detailed data sets to enable comparisons between bioregions.
Page last updated: 27 February 2011