Patterns of Picea mariana (Black Spruce) Growth and Raised Bog Development in Victory Basin, Vermont

Abstract

Bubier, J. L. (Botany Department, Field Naturalist Program, University of Vermont, Bur? lington, VT 05405). Patterns of Picea mariana (black spruce) growth and raised bog development in Victory Basin, Vermont. Bull. Torr. Bot. Club 118: 399-4ll, 1991.?In Victory Basin Bog, Vermont, a distinct zonation of Picea mariana (black spruce) occurs from an adjacent stream to the bog center, typifying a pattern in bogs throughout the boreal region. Height and density of P. mariana decrease toward the bog center, but age does not. The growth rate of P. mariana is greatest near the stream and declines away from it. This gradient in the heights of P. mariana accompanies a decrease in the mineral content of bog water toward the ombrotrophic bog center and an associated gradient in plant community composition. Raised bog development and stream incision appear responsible for the bog's elevated and sloping water table. Well data indicate that the slope and seasonal fluctuations of the water table are greater below the faster growing P. mariana than below the stunted P. mariana and open bog areas. Since a minimum of 5 m of peat underlie the entire study area, tree growth rates cannot be influenced by access to nutrients from the underlying mineral substrate. Peat stratigraphy suggests lateral bog ex? pansion and stream migration since peatland initiation in post-glacial times. The dynamic interaction between peatland and stream processes continues to influence patterns of P. mariana growth and stream migration.