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IDENTIFYING CRITICAL HABITAT |
Most non-game species and communities of conservation concern have specific habitat requirements. Habitat requirements may relate to foraging for food, protection from enemies, reproduction, or a combination of all three factors. Knowing where habitat for the species or community exists permits land managers to identify those areas most likely to contain the species or community. Similarly, being able to predict changes in habitat is often the first step in predicting impacts on the species or community of concern.
For example, at Fort Knox, Henslow's sparrow (Ammodramus henslowii) is a species of concern. This continental migrant bird will only nest in large areas of clumped, prairie-like grasses where the ground is not inundated during the nesting season and where there are few woody plants. Such habitat provides food and shelter from predators for the ground nesting bird. Without such habitat the bird cannot successfully reproduce.
Management of the Henslow's sparrow becomes a matter of protecting existing patches of habitat, which implies knowledge of the location of such patches. Although there are many grassy areas on Fort Knox, the only area previously known to be suitable habitat was near the Godman Army Airfield. Identifying other areas would involve some type of field survey based on a map of vegetation on the base. Using a geographformation system (GIS) we developed a habitat model for the Henslow's sparrow at Fort Knox, based on generally available geographical data such as a satellite image and county soil maps. This model predicts the locations of potential habitat. Field surveys can be focused on those areas identified by the model, thereby reducing the amount of time and effort required for field work. We produced a similar model for thecerulean warbler (Dendroica cerulea) at Fort Knox.
Another use of habitat models is to determine the impact of training or land management activities on species or communities of concern. We produced a habitat model for cedar barrens (or slope glades) at Fort Knox, based on several geographic layers (including land cover, soils, and geology). In order to determine whether and to what extent these barrens (glades) were at risk from tank training, we also developed a model of where tanks were most likely to go based on topography, the presence of suitable land cover, and the absence of wetlands [see Hargrove et al. (submitted)]. A video flyover shows the interaction between tank training sites and cedar barrens (glades).
Hargrove, W. W., T. L. Ashwood, L. K. Mann, and A. W. King. Deductive and inductive mapping of potential rare species habitat on military lands using a geographic information system. (submitted).
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