DOI: 10.25919/ks3e-7p22
title: HCAS 3.0 (1988-2022) base model estimate of habitat condition (250m grid), National Connectivity Index (NCI) 2.0, 3-year average annually rolling epochs of HCAS and NCI from 1990 to 2022, trends and other derivatives for continental Australia

description: Please cite as follows: Valavi R, Williams KJ, Liu N, Levick S, Giljohann KM, Johnson S, Botha EJ, Munroe SEM, Lehmann EA, Collings S, Searle R, Van Niel TG, Newnham G, Paget M, Joehnk K, Hosack GR, Harwood TD, Malley C, Gunawardana D, Sivanandam P, Carlile P, Richards AE, Tetreault Campbell S, Schmidt RK and Ferrier S (2024) HCAS 3.0 (1988-2022) base model estimate of habitat condition (250m grid), National Connectivity Index (NCI) 2.0, 3-year average annually rolling epochs of HCAS and NCI from 1990 to 2022, trends and other derivatives for continental Australia. Data Collection 62484. CSIRO, Canberra, Australia. Landing page: https://data.csiro.au/collection/csiro:62484. 
 
This data collection comprises, for continental Australia, the 250m gridded Habitat Condition Assessment System (HCAS) version 3.0 (1988-2022) base model (HCAS v3.0) estimation of habitat condition for terrestrial biodiversity, updated National Connectivity Index (NCI) v2.0 using the HCAS v3.0 base model, 3-year antecedent average rolling short-term epochs of HCAS, NCI, connectivity-adjusted condition (NCIC) and Ecosystem Site Condition (ESC) from 1990 to 2022, trends and other derivatives for continental Australia. The HCAS v3.0 short-term epochs are derived from the base model, and the NCI, NCIC and ESC short-term epochs use the corresponding HCAS v3.0 epochs as an input (production version 3-2). Several other datasets support use and interpretation of the base model, epochs and trends. 

Spatial raster datasets are provided in GeoTIFF format (*.tif) at 250m grid resolution, Geographic Datum of Australia (GDA) 1994 (Australian Albers, EPSG:3577). The original data, in a grid of 0.0025 degrees of latitude and longitude (EPSG:4283, GDA 1994), was projected to Australian Albers. Continuous data were bilinearly resampled resulting in some smoothing across pixels. Therefore, the unprojected data (EPSG:4283) are also provided as an option available to users. All GeoTIFFs are provided as Cloud Optimised GeoTIFFs (COGs). COGs are regular GeoTIFF files with an internal organisation to enable HTTP GET range requests to ask for just the needed parts of a file. In most cases, a corresponding *.png map image is also provided for quick views. 

The HCAS v3.0 base model and epoch datasets are Habitat Condition indices that vary continuously from a theoretical minimum of 0.0 (ecosystem integrity removed) to a maximum of 1.0 (ecosystem integrity in reference condition). The same definition applies to Ecosystem Site Condition (ESC). The NCI also ranges continuously from 0.0 (unconnected removed habitat) to a maximum of 1.0 (fully connected intact habitat), as does the NCIC: from 0.0 (ecosystem integrity functionally extinguished) to a maximum of 1.0 (ecosystem integrity functionally connected and in reference condition). 

The data extent of the curated projected collection is defined by any data pixel that intersected a coastline polygon using the land fraction dataset developed by Liu (2024) and the extent of National Land use data (ABARES, 2024b). The data and no-data extent of each grid layer encompasses the area within the Australian Continental Exclusive Economic Zone (EEZ), excluding territories of Cocos, Christmas, Norfolk, Macquarie, Heard, and McDonald Islands, as well as Antarctica (Liu and Newnham, 2024). 

This HCAS v3.0 product suite substantially improves on and extends the former HCAS series 2 outputs. HCAS v3.0 uses 14 remotely sensed ecosystem characteristics derived from the Digital Earth Australia Surface Reflectance NBART Landsat Analysis Ready Data Collection 3 derivative products (Commonwealth of Australia, 2021). HCAS v3.1 supersedes HCAS v3.0. 

Data descriptions are summarised in the accompanying "Habitat Condition Assessment System version 3.0: A guide to the 250-metre data collection" documentation, which can be downloaded separately from CSIRO's publication repository (see related links).