PLANT-COMMUNITIES OF A TUSSOCK TUNDRA LANDSCAPE IN THE BROOKS RANGE FOOTHILLS, ALASKA

We present the first vegetation analysis from the Arctic Foothills of northern Alaska according to the Braun-Blanquet approach. The data are from the Imnavait Creek and Toolik Lake regions. We focus on associations of dry and mesic upland surfaces and moderate snow accumulation sites; other upland plant communities, i.e. those of blockfields, nonsorted circles, and water tracks, are briefly described. Summary floristic information is presented in a synoptic table. Five associations and 15 community types are tentatively placed into seven existing syntaxonomical classes. The community descriptions are arranged according to habitat: dry exposed acidic sites, moist acidic shallow snowbeds, moist non-acidic snowbeds, moist acidic uplands, and moist nonacidic uplands. Many of the communities are Beringian vicariants of associations previously described from Greenland and the European Arctic. The described communities have a widespread distribution in northern Alaska. The relationship of the associations to complex environmental gradients are analyzed using Detrended Correspondence Analysis. Community composition is controlled primarily by mesotopographic relationships (slope position and soil moisture), microscale disturbances, and factors related to long-term landscape evolution.