Caribou habitat mapping and fragmentation analysis using Landsat MSS, TM, and GIS data in the North Columbia Mountains, British Columbia, Canada

Fragmentation of critical early winter caribou habitat in the North Columbia Mountains near Mount Revelstoke and Glacier National Parks in British Columbia, Canada, may be occurring as a result of timber harvesting and wildfires. In this research, habitat suitability models derived from Landsat Multispectral Scanner (MSS) imagery for 1975 and Thematic Mapper (TM) imagery for 1997 were developed to represent the landscape for the study area in a past (1975) and more recent condition (1997). A Hybrid Decision Tree (HDT) Classifier was used to combine maximum likelihood decision rules, a brightness differencing technique, and a spatial/contextual rule base. Verified by field samples and aerial photographs, the accuracy of the resulting habitat unit maps was determined to be 91.8% overall in the 1997 TM classification and 89.5% overall in the 1975 MSS classification. Based on a comparative analysis of selected spatial landscape metrics calculated for each time period, changes in the composition and spatial configuration of early winter habitat were quantified. Overall, the amount of suitable winter habitat available in 1997 represented a decrease of approximately 832.88 ha (8.53%) from 1975 levels. In the observed disturbance pattern, early winter habitat patches in 1997 were smaller and more uniform in size than in 1975, as suggested by decreases in mean patch size and patch size coefficient of variation indices. Spatial pattern analysis results indicated a reduction in geometric complexity, interior core area, and mean proximity between 1975 and 1997, while patch density and edge density had increased over time. The interpretation of changes in landscape structure are consistent with those reported in the literature for other regions, and indicate that fragmentation of early winter caribou habitat has occurred in the study area.