Green Mountains, Vermont

Green Mountain study plots. The Green Mountains of Vermont run north-south through the entire length of the state and include several peaks exceeding 1200 m. In 1964, Thomas Siccama (currently at Yale University) surveyed one transect along an elevational gradient on the western slope of each of four of the tallest of the Green Mountains: Mt. Abraham (44°07’N, 72°56’W, 1221 m), Bolton Mountain (44°27’N, 72°50’W, 1121 m), Camels Hump (44°19’N, 72°53’W, 1244 m), and Jay Peak (44°55’N, 72°32’W, 1177 m). We resurveyed these four transects during the summer of 2004 in order to compare the distribution of tree species over the intervening 40 years. These slopes were initially selected for study because they share similar exposure, a lack of secondary ridges above 550 m, and the absence of significant recent disturbance. Unfortunately, we were not able to use the transect on Jay Peak because it has been extensively disturbed by logging and recreational activities (ski slopes) since the initial survey.

These study sites share similar, distinctly zoned, overstory vegetation, with northern hardwood forest, dominated by sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Ehrh.), and yellow birch (Betula alleghaniensis Britton), on the lower slopes giving way to spruce-fir boreal forest, dominated by red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea Mill.), and montane paper birch (Betula papyrifera var. cordifolia (Regel) Fern), at upper elevations. The deciduous-boreal ecotone (DBE), a narrow band containing species of both lower and upper elevations, occurs between about 700 m and 900 m. Balsam fir forms almost monotypic stands from about 1100 m to treeline on Mt. Abraham and Camels Hump, and to the wooded summit on Bolton Mt., with trees taking krummholz growth form near treeline. The study plots established in 1964 were located every 60.96 m (200 ft) of elevation rise along a transect from 549 to 1158 m on Mt. Abraham and Camels Hump, and from 549 to 1097 m on Bolton Mountain, as the summit is lower than 1158 m.