The scientific framework for the NRS is based around Australia's bioregional framework.
This framework is a nested series of bioregionalisations beginning at the broadest scale with the biogeographic realms of the world developed by WWF. Australia is a major part of the Australasia biogeographic realm.
The world is also split into 14 terrestrial habitats of which eight are shared by Australia. The Australian land mass is divided into 89 bioregions and 419 subregions. Each region is a land area made up of a group of interacting ecosystems that are repeated in similar form across the landscape. See Australia's bioregion maps
Conceptual model of the bioregional framework
Bioregions are large, geographically distinct areas of land with common characteristics such as geology, landform patterns, climate, ecological features and plant and animal communities.
The bioregions are described in the interim Biogeographic Regionalisation for Australia (IBRA). IBRA is the National Reserve System's planning framework, the fundamental tool for identifying reservation targets and setting priorities to meet them. Earlier versions of IBRA have been used to define global terrestrial habitats and world ecoregions in Australia by the WWF and Trust for Nature. Subdivisions of IBRA regions undertaken in 2000 created the IBRA subregions to provide a finer scale break up of the Australian landscape.
Vegetation community and land system mapping undertaken by the states and territories have been used to establish IBRA Region and Subregion Boundaries. This information can potentially be used to identify regional ecosystems across Australia. At present there is no consistent identification and mapping of regional ecosystems in Australia although some states like Queensland have regional ecosystems identified and mapped.
IBRA is progressively updated as new scientific knowledge or new protected areas are added, making it a dynamic tool for monitoring progress towards building a CAR reserve system. IBRA7 is now available.
By combining the information about protected areas in Australia with the IBRA region, the level of protection of Australia's various landscapes can be measured. Assessing the level of protection assists governments to decide how to best prioritise funding and other resources to meet national protection targets.
In building the NRS, the main priority is to address the key gaps in comprehensiveness at the national scale. The top priority is the protection of ecosystems that are currently poorly reserved or not protected at all.