PARENT SESSION
Oral Session #12: Landscape Ecology: Theory and application. Presiding: C. Johnston.
Monday, August 6, 2001. 1:00 PM to 5:00 PM. Madison Ballroom D.
Spatiotemporal rates of land cover change since 1973: Regional examples from a national study.
Gallant, Alisa1, Loveland, Thomas1, Sohl, Terry2, 1 2
ABSTRACT- The USGS is applying nearly 30 years of Landsat data for a study of land cover dynamics across the conterminous U.S. Our hypothesis is that changes in land cover vary in time and space. To test this, we have selected random sample sites in each of 84 ecoregions, where we map land cover and measure change for four time periods from 1972-1992 (year 2000 data will subsequently be added). Each rectangular sample is 20 km on a side and is classified into 11 potential categories of land cover. Our goal is to distinguish 1% change in land cover, with 85% precision. Preliminary findings support our hypothesis. In the North Central Appalachians Ecoregion, for example, every land cover type exhibited less than 1% change in total area over time. There, the dynamics primarily revolved around very small, dispersed forest clearcuts. Similarly, in the Southeastern Plains Ecoregion, land cover types also changed little in total coverage, but the forestry in this ecoregion has been on an industrial scale. While 5% of the North Central Appalachians experienced change during the period analyzed, 14% of the Southeastern Plains was affected, astounding considering the size of this region (335,280 km2). We also observed a doubling in the amount of area harvested annually here. There are many dimensions of change, and we have learned that determining the most effective way of communicating the information is challenging.
KEY WORDS: land cover/use dynamics, disturbance, remote sensing