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, orthorecti fied aerial photography were used in combination with extensive ground -truthing to map and analyze the major zones (e.g., patch forest, krum mholz) and zone limits within the forest-tundra ecotone of Rocky Mount ain 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 disturb ance, in contrast to forest-tundra ecotones in arctic locations. The e cotone is patchy and the scale of patchiness is similar in the krummho lz and patch forest zones, although krummholz patchiness is derived mo re from rock outcrops and meadow/wetland areas and less from natural d isturbance than is the case for the patch forest zone. Scanned aerial photography may be useful for GIS analyses of ecotones and detection o f global change, but spectral variation among photographs, the need fo r adequate ground control and DEM precision for accurate ortho-rectifi cation, and the errors introduced through digitizing and interpretatio n ore limitations.