Brief description
Caveat: this dataset extends the annual epochs used in the HCAS v2.1 data collection but may not represent an improvement in the regional accuracy of condition assessments. Please read the accompanying technical report for method details. This dataset has a limited distribution because it is under revision and will be superseded by HCAS v3.0 with anticipated publication in mid-2024.This data collection comprises, for continental Australia, the 9-arcsecond gridded Habitat Condition Assessment System (HCAS) version 2.4 (2001-2018) base model (HCAS v2.4) estimation of habitat condition for terrestrial biodiversity, a series of 18-year epochs (including updated NCI v2.0), annual epochs between 2001 and 2021 derived from the base model, and a series of trend analyses derived from the annual epochs. Several other datasets support use and interpretation of the base model, epochs and trends.
The core collection in the HCAS v2.4 product suite comprises 32 datasets (four 18-year epochs, 21 annual epochs, seven trends), and a larger number of input and supporting datasets to inform use and interpretation, including four corresponding 18-year epochs of the NCI v2.0. The majority are raster datasets in GeoTIFF format (*.tif) at 0.0025° resolution (approx. 250 m grids), Geographic Datum of Australia (GDA) 1994 (EPSG:4283). All GeoTIFFs are also provided as Cloud Optimised GeoTIFFs (COGs) in relevant subfolders labelled ‘COG’. 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.
The HCAS v2.4 base model and epochs 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 index represents the contribution that a given site (grid cell) makes to the effective area of ecosystem integrity remaining within any given spatial reporting unit, expressed as a proportion of the contribution made by a site in reference condition.
This HCAS v2.4 product suite was developed to extend the annual epochs through to 2021, using remote sensing generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite. The MODIS satellite is reaching its end of life and future HCAS updates will be developed using Landsat satellite imagery, as well as other satellite inputs. The MODIS satellite will continue to operate, in a declining orbit, through to December 2025.
Note: The remote sensing data originally derived for these analyses included the calendar year 2022. However, investigations into reasons for a downward trend in the continental average of the 2022 condition epoch compared with the 2021 epoch, led to the discovery of a data download error in the remote sensing imagery. Missing tiles across some regions of Australia led to erroneous habitat condition estimates using the 2022 data. This affected the 2022 annual epoch, and the 2005–22 and 2001–2022 long-term epochs). The effect is muted in the continental average of the long-term epochs but obvious in analyses using the annual epoch. Therefore, results using the 2022 data were removed from this data collection. Because the analyses using these data for the EN01 measure in the DCCEEW 2022-23 Annual Report were presented as continental and land zonal averages, the data bias error in 2022 does not alter that overall result.
Technical report: Williams KJ, Valavi R, Lehmann EA, Van Niel T, Harwood T, Newnham G, Paget M, Donohue R, Giljohann KM, Liu N, Lyon P, Pinner L, Malley C, Deb D and Ferrier S (2023) Habitat Condition Assessment System (HCAS): developing HCAS v2.4 with annual epochs updated to 2021. Publication number EP2023-4902. CSIRO, Canberra, Australia. https://publications.csiro.au/publications/publication/PIcsiro:EP2023-4902.
Details are summarised in the product brief provided with this data collection.
Lineage: The HCAS v2.4 product suite was developed using a combination of:
a) time series remotely sensed ecosystem characteristic variables, derived from the CSIRO MODIS fractional cover dataset (Guerschman and Hill, 2018) and MODIS persistent and annual vegetation cover (Donohue et al., 2014; Donohue et al., 2009), derived from MODIS Collection 6.0 ;
b) gridded environmental covariates, including climate from the 9s climatology for continental Australia 1976-2005 (Harwood et al., 2016a), soil and landscape data from the Soil and Landscape Grid of Australia aggregated to 9s (Gallant et al., 2018), used to predict reference ecosystem condition; and
c) Spatially inferred reference sites sampled to represent Australia’s varied environments, used as training data to build the model of reference ecosystem condition and as benchmarks for calculating proximity to reference condition for all test sites.
Specifically, the HCAS v2.4 reference ecosystem model was developed using a generalised additive model (GAM) with c.239,000 reference sites, 27 environmental covariates and seven remotely sensed ecosystem characteristic variables summarised over 18 years (2001 to 2018). The base model was developed using the 2001–18 long term epoch for comparability with the original HCAS v2.1 (Harwood et al., 2021). The same seven ecosystem characteristic fractional cover summary variables derived from the MODIS satellite were used. This is the last year in which the MODIS satellite can provide reliable Earth observations, as it reaches its end of life. Future HCAS versions will transition to alternative ongoing Earth observation platforms (e.g. Landsat).
The HCAS v2.4 differs from the original HCAS v2.1 in the following ways:
• The number, location and ecological representativeness of the reference sites (including expert nominated inclusions and exclusions)
• The algorithm used to partition remotely sensed persistent and recurrent green cover fractions (the algorithm used to derive litter and bare fractions remained the same)
• The number of environmental covariates used to model reference ecosystem patterns
• Corrected variance standardisation of remotely sensed ecosystem characteristic variables for principal components
• The use of univariate generalised additive modelling (GAM) to model the remotely sensed ecosystem characteristic principal components and predict the ecosystem reference state
• The same reference sites used as training data were also used as benchmarks
• The scaling method applied to the uncalibrated output to obtain the 0-1 score
• The method of summarising remotely sensed ecosystem characteristic variables for use in annual condition epochs of habitat condition (summary variables for the long term epochs remained the same)
• Annual epochs were extended by three years to 2021 (21 in total, calendar years)
• Additional 18-year epochs were generated: 2002–19, 2003–20, 2004–21.
Technical report: Williams KJ, Valavi R, Lehmann EA, Van Niel T, Harwood T, Newnham G, Paget M, Donohue R, Giljohann KM, Liu N, Lyon P, Pinner L, Malley C, Deb D and Ferrier S (2023) Habitat Condition Assessment System (HCAS): developing HCAS v2.4 with annual epochs updated to 2021. Publication number EP2023-4902. CSIRO, Canberra, Australia. https://publications.csiro.au/publications/publication/PIcsiro:EP2023-4902.
This technical report provides details about the inputs, processing methods and outputs, with a focus on work leading to development of HCAS v2.4 and comparison with the original HCAS v2.1.
This data collection also includes an update to the National Connectivity Index version 2.0 (NCI v2) using the HCAS v2.4 as an input.
Details are summarised in the product brief provided with this data collection.
Available: 2024-12-16
Data time period: 2001-01-01 to 2021-12-31
Subjects
2001 |
2002 |
2003 |
2004 |
2005 |
2006 |
2007 |
2008 |
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
2015 |
2016 |
2017 |
2018 |
2019 |
2020 |
2021 |
Accounting, Auditing and Accountability |
Commerce, Management, Tourism and Services |
Conservation and Biodiversity |
Engineering |
Environmental Sciences |
Ecological Applications |
Environmental Assessment and Monitoring |
Environmental Management |
Geomatic Engineering |
HCAS |
Habitat Condition Assessment System |
Landscape Ecology |
MODIS |
Photogrammetry and Remote Sensing |
Sustainability Accounting and Reporting |
annual epoch |
bare ground |
biodiversity |
climate |
collection 6 |
ecosystem accounts |
ecosystem condition |
ecosystem integrity |
environmental-economic accounting |
epoch |
fractional cover |
landform |
litter |
persistent vegetation cover |
recurrent vegetation cover |
reference condition |
reference site |
remote sensing |
satellite |
site condition |
soil |
substrate |
surface water |
terrestrial |
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Identifiers
- DOI : 10.25919/5SGF-5G09
- Handle : 102.100.100/659911
- URL : data.csiro.au/collection/csiro:59210
