Analgzing long-term changes in vegetation with geographic information system and remotely sensed data

Abstract

Geographic information systems and remote sensing techniques are powerful tools in the analysis of long-term changes in vegetation and land use, especially because spatial information from two or more time intervals can be compared more readily than by manual methods. A primary restriction is the paucity of data that has been digitized from earlier periods. The Illinois State Geographic Information System has a number of automated data sets containing land-use information, including original land survey plat maps that show the boundaries of forests, prairies, and wetlands as they existed prior to European colonization in the early 1800s. More recent data include the United States Forest Service inventories of 1948, 1962, and 1985; the United States Geological Survey Land Use Data Analysis; National High Altitude Program photographs of vegetation; and Landsat MSS and TM information. These data can be used to compare vegetation patterns and changes in land use over time and to suggest factors that may have caused or influenced these variations. Profound changes have occurred in the Illinois landscape since European settlement, primarily because of conversion to agricultural use; in certain parts of the state, however, urbanization has been the major factor contributing to changes.