Plant communities and soils in cryoturbated tundra along a bioclimate gradient in the Low Arctic, Alaska

摘要: Nonsorted circles and earth hummocks are important landscape components of the arctic tundra. Here we describe vegetation on these frost-heave features at seven study sites along a N-S-transect from Arctic Ocean to Foothills, Alaska. We established 117 releves in surrounding tundra classified according Braun-Blanquet sorted-table method. used Detrended Correspondence Analysis analyze relationships between environmental variables. identified nine communities: Braya purpurascens-Puccinellia angustata community (dry nonsorted circles, subzone C); Dryas integrifolia-Salix arctica tundra, Sal ic i rotundifol iae-Caricetum aquati l is ass. nov. (moist coastal Junco biglumis-Dryadetum integrifol iae D); Dryado bigelowii Walker et al. 1994 Scorpidium scorpioides-Carex aquatilis (wet Cladino-Vaccinietum vit isidaeae hummocks, E); Sphagno-Eriophoretum vaginati Anthelia juratzkanaJuncus biglumis E). The DCA ordination displayed types with respect complex gradients. first axis corresponds bioclimate/pH gradient, second disturbance/soil moisture gradient. Frost-heave dominated by lichens, whereas adjacent supports more dwarf shrubs, graminoids mosses. have greater thaw depths, bare ground, thinner organic horizons lower soil than morphology changes climatic large, barren dominating northern vegetated, less active dotting southern sites. Thawing permafrost possible shift plant composition due global warming could lead decline result loss heterogeneity.