SUBSTRATE TYPE AND THE DISTRIBUTION OF SUGAR MAPLE AT ITS ELEVATIONALLIMIT IN THE WHITE MOUNTAINS, NEW-HAMPSHIRE

The relationships between tree species distribution and substrate char acteristics were examined at the upper elevational limit of sugar mapl e (Acer saccharum Marsh.) in the White Mountain National Forest, New H ampshire. Four tree species were studied: sugar maple, balsam fir (Abi es balsamea (L.) Mill.), red spruce (Picea alberts Sarg.), and yellow birch (Betula alleghaniensis Britton). At 51 individual trees (greater than or equal to 2.5 cm diameter at breast height) of each species, ' 'substrate type'' was described based on the parent material, soil hor izons, depth and texture of the B and C horizons, nature of surface bo ulders, and the depth to and type of impermeable layer. Substrate type was significantly (p < 0.001) associated with tree species. Sugar map le was relatively more frequent on deep fine and compact tills, less f requent on washed or shallow till, and absent on shallow, organic, or grus (weathered granite) substrates. Red spruce, balsam fir, and yello w birch were less sensitive to substrate type. Red spruce and yellow b irch were most frequent on organic material or grus over rock. Balsam fir most frequently occurred on washed till. As the frequency of subst rates favorable to sugar maple declined with elevation, it is possible that the upper elevational range limit of this species is influenced by substrate availability.