NSW Habitat Link Value (HLV) Index

<strong>What is the NSW Habitat Link Value (HLV) Index?</strong>

The NSW Habitat Link Value (HLV) Index estimates the relative contribution each location across NSW makes to terrestrial habitat connectivity across multiple ecological scales. The HLV Index, when mapped, provides a visualisation of a region's connectivity network. A high HLV indicates that the area may function as an important corridor for a range of species movements and ecological processes such as foraging, dispersal and migration. Since the relative contribution a location makes to habitat connectivity can increase when habitat is lost elsewhere, an increase in HLV does not necessarily indicate an improvement in habitat connectivity. Therefore, the HLV Index should not be used to measure how well-connected habitat is at any location or within a region. The related <a href="https://datasets.seed.nsw.gov.au/dataset/nsw-nhi-index">NSW Neighbourhood Intactness (NHI) Index</a> is best suited to this purpose. The NSW HLV Index is a multi-scale application of the habitat link value (Li) analysis along with the related neighbourhood habitat area (Ni) that underpins the NSW NHI index.

<strong>How are the data created?</strong>

The NSW HLV Index is created using the NSW Habitat Intactness (HI) Index as an input to a multi-scale habitat link value (Li) analysis. Least cost paths between good condition habitats are mapped at different spatial resolutions then averaged at each 90 x 90m pixel location to measure its contribution to habitat connectivity generalised across a range of ecological scales. The NSW HI Index combines direct measures of remotely sensed vegetation cover with measures inferred from other data sources using expert input to estimate terrestrial habitat intactness (See the <a href="https://datasets.seed.nsw.gov.au/dataset/nsw-habitat-intactness-index">NSW HI Index Information Sheet</a> for further details).  

<strong>What data are available?</strong>

Data are initially available annually from 2017, currently with a two-year time lag for the most recent layer due to the availability of NSW Habitat Intactness inputs. Data for other periods may be generated as needed. Layers provide near-complete statewide coverage but are limited by the NSW Habitat Intactness inputs available at the time of each assessment, and their accuracy, currency and completeness.

Data details:   
<ul>
<li>Data type: raster, GeoTIFF, 32bit floating point</li>
<li>CRS: EPSG:3577 - GDA94 / Australian Albers </li>
<li>Pixel size: 90 x 90m</li>
<li>Pixel values: 0.0 (lowest HLV) to 1.0 (highest HLV)</li>
<li>Null value: -9999</li>
</ul>

<strong>What can the data be used for?</strong>

The NSW Habitat Link Value has been used to map ecological connectivity (<a href="https://www.environment.nsw.gov.au/publications/integrated-model-data-fusion-approach-measuring-habitat-condition-ecological-integrity-reporting">Love et al. 2020</a>) and provides a visualisation of a region's connectivity network. This mapping can be used to inform the connectivity strategy (priorities for improving the persistence of biodiversity) by highlighting opportunities for conserving, enhancing and building important habitat networks between concentrations of high-quality habitat. Connectivity can be mapped across structurally distinct habitat types and at various spatial resolutions, for jurisdictional reporting, and in the context of climate-induced shifts to environmental niches (<a href="https://www.sciencedirect.com/science/article/pii/S0304380021003963?via%3Dihub">Drielsma et al. 2022</a>). The HLV can be contextualised with additional sources of information to identify preferred habitat corridors for different contexts.   

Tags: Condition, Habitat connectivity, carrying capacity, connectivity, corridors, ecological connectivity, habitat condition
Organization: NSW Department of Climate Change, Energy, the Environment and Water