| Summary: | A two year study was conducted to evaluate the consequences of human trampling and elevated summer temperature on moist and dry arctic tundra. Field manipulations of trampling were applied in 0.75m2 plots and small, temporary greenhouses were erected to warm the soil and air temperatures. Plots were trampled at approximately peak seasonal biomass production at levels of 25, 75, 200 and 500 passes. At the end of the first season, 500 trampling passes resulted in approximately 50% cover loss in the dry tundra (Dryas octopetala dominated) and 70% cover loss in moist tundra (Eriophorum spp. and Carex spp. dominated). Relative height of the vegetation decreased in the moist tundra with increasing trampling intensity but was not as affected in the dry tundra. After two growing seasons, warmer summer temperatures resulted in increased percent cover, decreased leaf nitrogen, and increased leaves per ramet in D. octopetala.
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