APPLICATION OF A MOOSE HABITAT SUITABILITY INDEX MODEL TO VERMONT WILDLIFE MANAGEMENT UNITS
Habitat Suitability Index (HSI) models translate existing knowledge of a species’ habitat requirements into quantitative measures of habitat quality. The HSI is a numerical index that represents the ability of a given habitat to provide life requisites for a species on a scale from 0 (unsuitable habitat) to 1 (optimal habitat). Habitat Suitability Index models are useful in natural resource planning for predicting the impacts of resource management practices on wildlife habitat. Many moose (Alces alces) HSI models require the labor intensive collection of ground-level browse density data, which limits their applications for analyzing large landscapes required by moose. Some, however, have been developed utilizing remotely sensed data to analyze large study areas. I tested the usefulness of one of these models, created for the Lake Superior region, to 2 Wildlife Management Units (WMUs) in Vermont. Areas of study WMUs, “E1” and “I”, were 680 km2 and 729 km2, respectively. The model quantified 4 landscape-scale habitat variables representing annual cover types required by moose: percent area of regenerating forest, non-forested wetland, spruce/fir forest, and deciduous/mixed forest. Model analyses were performed using a Geographic Information System (GIS). The model was useful in estimating relative habitat suitability of both WMUs, identifying within-WMU habitat variation, quantifying change in habitat suitability following a natural habitat-altering event, and predicting temporal change in moose habitat due to changes in forest management practices. The model revealed significant differences in habitat suitability of 0.64 for WMU E1 and 0.34 for WMU I. To determine within-WMU habitat variation, both WMUs were divided into 25-km2 evaluation units, which approximated the annual home range of moose in New England, and a HSI was calculated for each unit. Habitat suitability of 81 km2 of WMU I increased from 0.30 to 0.53 due to an increase in regenerating forest following heavy canopy damage from an ice storm in January 1998. A reduction in habitat suitability from 0.81 to 0.35 of Silvio O. Conte National Fish and Wildlife Refuge lands within WMU E1 was observed following a simulation in which all timber harvesting as a forest management practice was eliminated. Initial validation of this model for analyzing moose habitat at the WMU scale is supported by correlation of HSI output to moose harvest data for WMU E1 25-km2 evaluation units and by comparison of HSI to estimated moose densities for both WMUs.
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