GEOGRAPHIC INFORMATION SYSTEM BASED ANALYSIS OF CURRENT AND HISTORICAL VEGETATION COMPOSITION IN EAST TEXAS

摘要

A U.S. Forest Service map of a regional survey of forest composition prepared in the mid 1930's was converted to a digital format in a Geographic Information System (GIS) and compared to 1984 vegetation data using spatial analysis. Comparison of the distribution of vegetation types mapped in 1935 with those mapped in 1984 based on data from the 1970's revealed changes in both relative importance and distribution of vegetation types. Some of these changes are due to differences in the manner in which the vegetation was classified, surveyed, and/or inaccuracies within and between the two surveys. Other changes appear to be due to forest management practices and to changes in land-use such as urbanization or conversion of forest to pasture or cropland. Overall, the total area occupied by forested lands in East Texas has declined only slightly, while loss and/or conversion of longleaf pine and bottomland hardwood forests appear to be more pronounced.