Multitemporal characterization and mapping of montane sagebrush communities using Indian IRS LISS‐II imagery

Abstract

The sagebrush landscape of Grand Teton National Park, Wyoming, forms four distinct communities: low sagebrush (Artemisia arbuscula); mountain big sagebrush (Artemisia tridentata); mixed low sagebrush/big sagebrush; and a big sagebrush/bitterbrush (Purshia tridentata) mosaic. Collectively, the sagebrush communities provide a significant source of forage for deer, elk, pronghorn antelope, and bison, particularly in winter. The objective of this research was to characterize seasonal changes in spectral reflectance for four sagebrush communities and to develop a multitemporal mapping procedure for the four sagebrush communities using Indian IRS LISS‐II multispectral satellite imagery. Results indicate that the four sagebrush communities can be best differentiated using visible bands of the IRS‐1B LISS‐II, independent of image date. Near‐infrared reflectance was of value for distinguishing between sites only in late fall (October). Statistically significant differences in NDVI values existed between the four communities only for summer dates (June and August) of imagery. Principal component analysis (PCA) was used to compress eight bands (two dates, four bands per date) of Indian IRS‐IB data into four PCA bands. A euclidean distance clustering algorithm was used to classify the four PCA components into forty spectral clusters. Field data acquired during summer 1996 and from the literature were used to identify and combine spectral clusters to produce a final map of sagebrush community types in Grand Teton National Park. Overall accuracy was 65%, and highest for the mixed big sagebrushAow sagebrush community at 86%.