Ecological Knowledge System: National Biodiversity Assessment System (NBAS) Data

Brief description

Collection: This collection contains derived datasets utilised in the National Biodiversity Assessment System (NBAS), developed as part of the Ecological Knowledge System (EKS). The EKS is a partnership between CSIRO and the Department of Climate Change, Energy, the Environment and Water (DCCEEW) to establish a transparent and authoritative source of information, biodiversity assessment and forecast capability for the Nature Repair Market. The NBAS is a software and data package that provides a nationally consistent approach to forecasting the expected biodiversity benefits of a given project within the Nature Repair Market scheme.

This collection comprises information about the ecosystem typology used in the NBAS. It contains (1) a raster that denotes the location and boundaries of the ecosystem types as defined in NBAS (i.e. the intersections between the National Vegetation Information System (NVIS) major vegetation groups (MVGs) and Conservation Management Zones (CMZs), (2) an ecosystem identification key for each ecosystem type in the raster, and (3) an NBAS ecosystem typology table which reports the pre-1750 and extant ecosystem extent data, excluding MVGs that represent unclassified ecosystems, bare ground, inland water, and predominately non-terrestrial based ecosystems. These datasets are used in the NBAS to forecast expected biodiversity benefits of nature repair projects.

The NBAS is implemented via the PLANR tool (https://planr.gov.au/).

This data collection is based on research created under the Project An Ecological Knowledge System for the Nature Repair Market scheme, which was funded by DCCEEW. The Commonwealth owns the intellectual property rights in any material developed while carrying out the Project. Copyright is retained by CSIRO (2025).

Background: The NBAS provides a nationally consistent approach to assessing a project site’s current contribution to conserving biodiversity and forecasting the biodiversity benefits expected to result from project activities.
The NBAS uses proportional persistence of native biodiversity as the ‘common currency’ of project assessment. Biodiversity persistence estimates the proportion of biodiversity that could be expected to exist without significant loss or decline, both now and into the foreseeable future.

The NBAS (Version 1) outputs the following metrics:
•\tEcosystem condition, which represents the capacity of an area to provide the structures and functions necessary for the persistence of all native species naturally expected to occur in that area if it were in an intact (or reference) state.

Ecosystem condition scores range from 0.0 (ecosystem integrity extinguished, ecosystem completely removed) to a maximum of 1.0 (ecosystem integrity in reference condition).
•\tLandscape connectivity, which estimates the system level contribution that a given area is estimated to make to enhancing the connectivity of habitat across the broader landscape.
•\tThe conservation significance of the ecosystem types being protected or enhanced, accounting for their natural rarity and their level of depletion and degradation.
•\tThe overall contribution that an area makes to enhancing biodiversity persistence at a system level, integrating the effects of the above three components.

Lineage: The NBAS products in this repository are derived from the following publicly available datasets (see Related Links):
•\tNVIS 6.0 pre-1750 Major Vegetation Groups (MVGs): Major Vegetation Groups are based on the structure, growth form, and floristic composition of the dominant vegetation layer.
•\tConservation Management Zones (CMZs) of Australia (2018): The 23 Conservation Management Zones of Australia are geographic areas, classified according to their ecological and threat characteristics. The zones are also aligned with the IBRA.
•\tGeneralised Dissimilarity Model (GDM): Eight 90 m GDM-transformed environmental grids and two geographic distance grids (x, y) generated from a GDM fitted to data from 115,086 plant community survey plots across Australia.
•\tHabitat Condition Assessment System (HCAS): This dataset uses remote sensing data to estimate ecological condition nationwide. NBAS relies on 90 m resolution data from the most recent short-term epoch (2020–2022).

To generate the ecosystem-typology raster, NVIS MVGs were intersected with CMZs. This intersection results in 485 ecosystem type combinations which form the ecosystem typology used in the NBAS. The ecosystem ID key provides the name and number of the MVG and the CMZ from which each ecosystem type in the raster is derived.
The intersection of MVG and CMZ sometimes divides MVGs into smaller subunits when they cross multiple CMZ boundaries. As a result, some of these ecosystem types may appear much ‘rarer’ than they are, given their close relationship to other subunits within the same MVG. To address this, the extent of each MVG subunit (MVG within a CMZ) is modified based on the proportion of species expected to be shared with other subunits within the same MVG using a GDM. The result of this analysis reflects the modified pre-1750 area of each ecosystem type which is then used as an input to the conservation significance metric.
The sum of all HCAS condition values occurring within each ecosystem type is combined with a connectivity adjustment to provide an estimate of the ‘effective’ remaining area of each ecosystem type. An equivalent modification for compositional similarity is also applied to the effective remaining area of each ecosystem type.

The NBAS ecosystem typology provides the unadjusted and modified pre-1750 area, and the unadjusted and modified current effective area (accounting for ecosystem condition via HCAS and connectivity) for each ecosystem type. The typology table does not include MVGs that represent unclassified ecosystems, bare ground, inland water, and predominately non-terrestrial based ecosystems. Excluded MVGs are::
•\t23 Mangroves
•\t24 Inland Aquatic - freshwater, salt lakes, lagoons
•\t26 Unclassified native vegetation
•\t27 Naturally bare - sand, rock, claypan, mudflat
•\t28 Sea and estuaries
•\t30 Unclassified forest

Further details of this analysis can be found in Section 3 and Section 4.2 of the Ecological Knowledge System (EKS) for the Nature Repair Market: Technical Report (see Related Links).