Overview of Gap Analysis
Basil G. Savitsky
GAP analysis is a “search for biotic communities and species in need of preservation management” (Davis et al. 1990:56). Gap analysis provides a method for assessing present measures to protect biological diversity and for identifying focus areas for optimal conservation efforts (Scott et al. 1987). Gap analysis is a GIS technique which superimposes species distributions with boundaries of ecosystems and protected areas to identify gaps in the protection of species. GIS is used to overlay maps or layers that are geographically referenced to each other and to create new information through the combination of those map files. Image analysis is used to create the vegetation database that provides the framework for the various GIS data layers. GPS has been used in conjunction with field components of image analysis and is beginning to be utilized as a wildlife data collection technology.
One tool that was developed during this project was the Habitat Conservation Decision Cube. The decision cube is covered in detail in chapter 15, but is introduced at this time as it defined the database design for the USAID project. The decision cube can be represented as a three-dimensional box with eight internal cubes (see figure 15.2). The eight cubes represent possible outcomes when three separate axes are viewed for the presence or absence of the three variables used in gap analysis. The three variables are the presence or absence of a species or group of species of wildlife; the presence or absence of suitable habitat for that species; and the presence or absence of protected areas. Each of the eight types of locations require different policy approaches. For example, gap analysis was designed to identify the locations where species and habitat are present that are outside of protected areas. Such locations adjacent to or between protected areas are prioritized in land acquisitions for conservation purposes.