MORPHOLOGICAL CHANGES IN REGROWN SALIX ARBUSCULOIDES FOLLOWING CLEAR CUTTING IN THE CANADIAN SUBARCTIC

In a Picea mariana forest near Fort Norman, NWT, Canada, a corridor was cleared in the spring of 1985 to simulate a seismic line or pipeline disturbance. Salix arbusculoides, the dominant erect shrub, was monitored for three growing seasons after canopy harvesting. Leaf area was not consistent between the three years in either the cleared right-of-way or the undisturbed forest control area. Relative to control shrubs, leaves were significantly larger in right-of-way shrubs in 1985, virtually identical in size in 1986, and smaller in the right-of-way shrubs in 1987. In 1986, stem production was so great for right-of-way shrubs that the mean leaf/stem biomass ratio for this sample was smaller than both the other two years for right-of-way samples and the control sample for that year. Right-of-way shrubs were consistently shorter in height than control shrubs; by the third growing season, however, this difference was negligible. Right-of-way shrub canopy volume was significantly less than control shrubs only in the first growing season of recovery (right-of-way shrub volume averaged 85% of control shrub volume). By the second growing season after harvesting, right-of-way shrubs had attained canopy volumes that were no longer significantly less than control shrubs. Although the average canopy volume of right-of-way shrubs approached that of control shrubs as time passed, the right-of-way shrubs maintained a lower, broader morphology, as reflected in the height to mean canopy diameter ratio which was typically lower for right-of-way shrubs. Key words: plant morphology, vegetation disturbance, subarctic, Canada.]