摘要：The distribution of alpine tundra in the Adirondack Mountains of New York was investigated through a combination of field mapping and GIS analysis. Alpine tundra vegetation covers 26.3 ha (65 acres). Tundra patches are rare below an elevation of 1350 m although significant differences exist in mean tundra elevation between summits reflecting overall summit morphology. Tundra is generally more abundant, and extends to lower elevations on windward slopes with northerly and northwesterly aspects. Tundra patches on leeward slopes are found at higher elevations and are considerably larger, reflecting increased fragmentation on windward slopes and development of snowbank communities on leeward slopes. At a regional scale, the percentage of high-elevation land covered by tundra decreases from the northwest to southeast across the study area, suggesting that mountains upwind along the prevailing winter wind vector shield downwind summits, underscoring the role of exposure in limiting the upward growth of trees. Because exposure exerts a fundamental control over patch boundaries, shifts in the balance between arboreal and non-arboreal vegetation over time could be expected if changes occur in the frequency of icing events, the severity of winter storms, temperature, cloudiness, or prevailing wind directions.
