Landsat MSS-derived land-cover map of northern Alaska: extrapolation methods and a comparison with photo-interpreted and AVHRR-derived maps

Vegetation maps of Arctic areas are needed for a variety of tundra ecosyste m and climate change studies and for extrapolating from relatively small, w ell-known sites to broader regions. We made a preliminary land-cover map of northern Alaska by extrapolating a Landsat Multi-Spectral Scanner (MSS)-de rived classification of the Kuparuk River Region (KRR) to all of northern A laska. We used a 26-scene mosaic that was previously made by the EROS Data Center, and a K-means unsupervised classification algorithm to produce eigh t broad land-cover categories. The northern Alaska-MSS map (NA-MSS) has the following land-cover categories and respective percentage coverage within the 200 000km(2) Arctic Slope: Dry Prostrate-shrub Tundra and Barrens, 8%; Moist Graminoid, Prostrate-shrub Tundra, 22%; Moist Tussock-graminoid, Dwar f-shrub Tundra, 4%; Moist Dwarf-shrub, Tussock-graminoid, Tundra, 28%; Mois t Low-shrub Tundra and other Shrublands, 19%; Wet Graminoid Tundra, 9%; Wat er, 6%; Clouds and ice, <1%; Shadows, 4%. Ancillary data were used to impro ve the classification for a region of sandy tundra not encountered in the K RR and to separate shadows in the mountains from water and wetlands elsewhe re. The NA-MSS map helps to define the distribution of a recently described moi st nonacidic (calcareous) tundra and areas of shrublands that are of broad interest to the tundra- and climate-change modelling communities. A boundar y separating moist acidic tundra from moist nonacidic tundra stretches acro ss all of northern Alaska (about 850 km). Shrub-dominated tundra is prevale nt in the southern and western (warmer, wetter) portions of the map. We cre ated difference maps for comparing the northern Alaska-MSS (NA-MSS) map to the Major Ecosystems of Alaska (MEA) map and a map derived from a time seri es of Advanced Very High Resolution Radiometer images (NA-AVHRR). Compared to the other maps, the NA-MSS map provides more detailed information for mo ist tundra areas and shows more shrub-dominated vegetation with different s patial distributions than the other two maps. An accuracy assessment of the map will be performed in 1999.