Vegetation, Soil, and Climate on the Green Mountains of Vermont

Abstract

The Appalachian extension of the Boreal Forest, dominated by balsam fir, red spruce, and white birch, extends down the slope of the Green Mountains to about 2,600 ft (792 m), where it merges with the Eastern Deciduous Forest dominated by sugar maple, beech, and yellow birch. These two forest formations occur as well—developed horizontal bands on the mountains, with a distinctive tension zone forest between them. In this midslope forest the species of neither the deciduous nor boreal forest are able to form well—developed long—lived stands. The contact between the deciduous and boreal forest is climatically, not edaphically, controlled. The current vegetation and soil development is the result of the long—term effects of a vertical climatic discontinuity expressed as a nonlinear decline in the length of the frost—free period across the midslope transitional forest and as a marked increase in the frequency of the cloud base at and above ca. 792 m. This results is increased moisture from fog drip and frequent occurrence of hoar frost in winter. The sharp decrease in the length of the growing season, together with marked changes in icing and atmospheric moisture conditions, limits the upward extension of the beech—maple forest.