Plant Water Relations in Montane and Tussock Tundra Vegetation Types in Alaska

Abstract

Plant water potentials and related environmental factors in different montane tundra types occurring in a gradient of snow accumulation and in tussock tundra were measured in order to relate tundra vegetation to environmental gradients in Alaska [USA]. Plant water potentials, air and soil temperatures, air humidities and solar irradiance were measured through the day every 2 wk during the 1977 growing season in central Alaska and between 27 July and 5 Aug. in Eriophorum vaginatum tussock tundra in central, western, and northern Alaska. The vegetation types studied included tussock tundra, fellfield, lichen heath, deciduous shrub, forb-grass, evergreen shrub (Cassiope), and sedge-moss. The Cassiope zone had the shortest growing season, determined by late-lying snow and water stress, the highest temperatures, but the lowest seasonal temperature sums. Plant water potentials in the fellfield and lichen heath were moderate. Water potentials in tussock tundra in central, western, and northern Alaska were similarly high. In most vegetation types, water potentials were moderate, low water potentials occurred only in shallow rooted shrubs and in the Cassiope zone.