POST-FIRE CHARACTERIZATION OF THE LAND SURFACE AND VEGETATION USING IMAGING SPECTROSCOPY DATA FOR CERRO GRANDE NM AND LEFT HAND CREEK WY

Historically, fire has been among the dominant disturbances in the Rocky Mountain Region of the U.S. Recent occurrences of large wildfires, due in part to the increased abundance of fuels resulting from the past century of wildfire suppression, necessitate that resource managers acquire information on the post-fire state of the land surface to plan erosion hazard mitigation strategies and to guide re-vegetation efforts. This paper reports on the spectroscopic analysis of remotely sensed data collected post-wildfire. Two areas were studied: 1) the May 2000 Cerro Grande fire in Los Alamos NM, and the Left Hand Creek BLM area in Central Wyoming, which has been subject to wild fires in 2000 and 2001. AVIRIS data collected on September 4, 2000, over the Cerro Grande fire were atmospherically corrected and converted to reflectance using a single ground calibration site. The spectral signatures in these data were examined in relation to known spectral responses of vegetation, mineral and post-fire ash materials. The results in this study area indicate that the presence of ash covered surfaces and bare soil/bedrock surfaces can be identified and mapped. Variations in vegetation absorption features arising from chlorophyll and lignin/cellulose indicate that vegetation within fire perimeters can potentially be discriminated into unburned vegetation, fire-killed non-photosynthetic needles/leaves, and regenerated vegetation. Hymap imaging spectrometer data over the Left Hand Creek study site were collected on July 2, 2002. In conjunction with the remote sensing data collection, field measurements of vegetation reflectance and surveys of plant species composition were made for 33 sites within the study area. Measurements of vegetation cover and species composition were made in order to assess the impact of fire on vegetation regeneration in this sagebrush ecosystem. Ongoing efforts in both study areas seek to utilize the post-fire characterization of the land surface in conjunction with in situ studies of erosion and vegetation regrowth to develop predictive models of landscape recovery from wildland and prescribed fires.