干旱区生态环境知识资源中心

On Axel Heiberg Island, Nunavut, Canada, a banded vegetation pattern occurred on a hillside where patterned ground and unidirectional abiotic fluxes, such as downslope water flow or wind, were not present. The parent material was the obvious source of the plant pattern, as the soils occurred on five distinct types of alluvial deposits. To examine the observed pattern, plants were inventoried and soils were sampled in July 1999. Twelve vascular species of plants, but no non-vascular species, were present at the site. Neither water, often thought to limit plant distribution in the High Arctic, nor any of the other measured soil variables, predicted plant abundance. The best predictor of plant abundance, based on regression tree analysis, was total soil nitrogen; however, higher plant density was associated with lower nitrogen. The five soil types differed in plant density and soil properties. Even though the sand soil always had soil nutrients equal to or lower than the blocky clay soil, the sand and clay soils had the highest plant density and the blocky clay soil the lowest. Although the vegetation pattern is obvious, the underlying mechanism creating the pattern is not.