USING AERIAL-PHOTOGRAPHY AND GIS TO MAP THE FOREST-TUNDRA ECOTONE IN ROCKY-MOUNTAIN NATIONAL-PARK, COLORADO, FOR GLOBAL CHANGE RESEARCH

Ecotones could be useful locations to monitor the potential effects of global change on the biosphere. The GRASS GIS and scanned, orthorectified aerial photography were used in combination with extensive ground-truthing to map and analyze the major zones (e.g., patch forest, krummholz) and zone limits within the forest-tundra ecotone of Rocky Mountain National Pork in the Colorado Front Range. Only a small percentage of the 1,092-km length of zone limit-lines, and the 49,520 ha within the patch forest and krummholz zones, bears evidence of recent disturbance, in contrast to forest-tundra ecotones in arctic locations. The ecotone is patchy and the scale of patchiness is similar in the krummholz and patch forest zones, although krummholz patchiness is derived more from rock outcrops and meadow/wetland areas and less from natural disturbance than is the case for the patch forest zone. Scanned aerial photography may be useful for GIS analyses of ecotones and detection of global change, but spectral variation among photographs, the need for adequate ground control and DEM precision for accurate ortho-rectification, and the errors introduced through digitizing and interpretation ore limitations.