The Point Bar Environment in the Mackenzie River Delta

Abstract

Helicoidal flow and sediment sorting along the convex portion of shifting channels in the Mackenzie River Delta cause point bars to be composed of the coarsest material available to plant colonization. Sorting by aeolian action further reduces the fine fraction in point bar soils. Coarse-textured deposits maintain a lower water content and a higher soil temperature than other deltaic surfaces, thus nearly every point bar is colonized by a discrete plant association. This ecosystem is dominated by balsam poplar (Populus balsamifera), and the distribution of well developed poplar stands is restricted to point bars. The successional ecology of this ecosystem is discussed in relation to the point bar environment.