The Arc Habitat Suitability Index is a geographical information system (GIS) model that estimates the ability of an area to meet the food and cover requirements of an animal species. ArcHSI is a tool intended to inform planners of the probable impacts on wildlife for the alternatives they develop. It is a tool that should augment, not supplant, the expertise of resource specialists with site-specific knowledge.
ArcHSI has several advantages over tabular summaries of habitat coefficients appearing in early versions of habitat capability models. Retaining prior analyses and modeling vegetation changes over time allows fairly easy assessment of cumulative effects.
The GIS output, even for species for which model components are not spatially explicit, allows users to visually display habitats for species and to make spatial inferences. For example, an analysis area can have uniformly moderate quality habitat or a mix of high quality and low quality habitats but have the same area-weighted average HSI. Identical treatment applied to these landscapes could have very different effects on HSI.
Therefore, we discourage using ArcHSI to influence land or resourcemanagement actions on the basis of model numeric output alone. We also discourage tabulating average HSI values and reporting them without considering the spatial distribution of habitats relative to the land area over which the modelis being applied.
We have included a demonstration that provides a step-by-step tour of the software, including setting up the first run; interpreting, formatting, and analyzing output; and identifying and solving the most common problems experienced by new users.
Primary input to a model is from the COVER_TYPE and HAB_STRUCT_ STAGE items of the Rocky Mountain Region Resource Inventory System (RMRIS Data Dictionary 1988). Data from these items are concatenated and matched (COVSS column) to a table of coefficients (table 1) to provide the FV and CV components. The tables of coefficients for all species and seasons of use are contained in a single file. As in the Habcap and ArcHabcap systems, coefficients range from zero for the poorest, to one for the best habitats.
ArcHSI output consists of an ArcINFO coverage, an INFO summary table, and when run in interactive mode, an open ArcVIEW project. The project displays the coverage and table in ArcVIEW automatically when ArcHSI is launched from its desktop shortcut. ArcVIEW displays the input vegetation coverage, the input roads coverage and the ArcHSI output coverage.
Project summary data are displayed in a table beneath the map. Table items are the number of vegetation units and number of acres in the area analyzed, mean FV, mean CV, mean HDV, and mean HSI. All means are weighted by the areas of the individual vegetation units. The default project categorizes HSI values as poor (0 to 0.33 HSI), fair (>0.33 to 0.67 HSI), or good (>0.67 HSI). This is a preliminary classification, useful as a starting point, but users are encouraged to explore more useful groupings.
A legend file, ELKHSI.AVL, specific to Black Hills elk has classification cutoffs at 0.30, 0.45, and 0.70 between poor, fair, good and excellent, respectively. We developed these cutoff points using cluster analyses of ArcHSI output and verified them with locations of elk from radio telemetry (Rumble and others, in press). Also included are legend files to display cover values (CV.AVL), feed values (FV.AVL), habitat distribution values (HDV.AVL), and vegetation cover type and structural stage (COVSS.AVL).
The components and parameters of the ArcHSI model occur in tables and can be easily edited or otherwise modified. ArcHSI runs on personal computers with the full installation of ArcGIS (Version 8.2+). System requirements are platform specific, but a typical system requires 512 megabytes RAM and a 1 gHz CPU. A Unix ArcINFO version is also available.
ArcHSI is a tool intended to inform planners of the probable impacts on wildlife for the alternatives they develop. It is a tool that should augment, not supplant, the expertise of resource specialists with site-specific knowledge. We discourage using ArcHSI to influence land or resource management actions on the basis of model numeric output alone. We also discourage tabulating average HSI values and reporting them without considering the spatial distribution of habitats relative to the land area over which the model is being applied.
ArcHSI should be applied to areas large enough to encompass the home ranges of individuals of the species under consideration. For example, elk in the Black Hills require a minimum home range of approximately 2,500 acres (1,012 ha) (Benkobi and others 2005). Consequently, the minimum area for which the elkmodel should be applied is approximately 2,500 acres.
Similarly, for any analysis to be meaningful, the area impacted by management must be large relative to the area of the entire project. Retaining prior analyses and modeling vegetation changes over time allows fairly easy assessment of cumulative effects.
Manual is from 2006.