The Maine GAP analysis project: Final report

Krohn, William; Boone, Randall; Sader, Steven; Hepinstall, Jeffrey; Schaefer, Sandra; Painton, Stephanie

From the executive summary: "The Maine Gap Analysis Project (ME-GAP) was initiated in 1992 as a cooperative effort between the Biological Resources Division of the US Geological Survey (USGS) and state, federal, and private natural resources groups in Maine. The objectives of ME-GAP were to: (1) produce databases for use in Geographic Information Systems (GIS) at a scale of 1:100,000 to describe current land cover, distributions of native species of terrestrial (i.e., non-fish, nonmarine) vertebrate species, ownership of conservation and public lands, and land management status; (2) identify land cover types and vertebrate species that currently are not represented or are under-represented in areas managed for long-term maintenance of biodiversity (i.e., identify conservation gaps); and (3) facilitate cooperative development and use of information so that institutions, agencies, and private land owners may be more effective stewards of Maine’s biological resources. ME-GAP is a preliminary step toward the more detailed studies and efforts needed for the long-term conservation of biodiversity in Maine. The system used to classify the land cover consisted of 37 types (19 upland types, 16 wetlands, 2 water). This classification was a compromise between the habitats needed to predict vertebrate distributions and those classes that could be discerned from satellite imagery and ancillary GIS databases. Landsat Thematic Mapper (TM) imagery from 1991 and 1993, in conjunction with aerial videography, was used to identify and map the water and upland types. Wetland polygons came primarily from the US Fish and Wildlife Service’s National Wetlands Inventory (NWI). NWI maps of Maine were done at 1:24,000 and based on aerial photographs mostly from the mid- and late-1980s. To facilitate the predicting of vertebrate species’ distributions, NWI wetland types, defined largely in terms of physiographic locations on the landscape, were re-labeled so types related to the occurrences of vertebrates in terms of vegetative and structural characteristics. A comparison of vegetation and land cover types mapped from TM data to aerial videography had an overall accuracy of 88.1% at the level of superclasses. For groups of Forestland classes, accuracy levels range from 45% to 80%; accuracy by types also varied geographically across the state as different TM scenes were used in various parts of the state."

The Maine GAP analysis project: Final report

See also