A comparison of mature with recently clear-cut and scarified lodgepole pine forests in the Lower Foothills of Alberta

Abstract

Mature, even-aged lodgepole pine (Pinuscontorta Dougl. var latifolia Engelm.) forests on upland sites with Orthic Gray Luvisols in the Lower Foothills of Alberta have been clear-cut for pulpwood and scarified by bulldozer since 1958. Undisturbed stands had weak shrub strata, well developed herb – dwarf shrub strata, and continuous feather moss strata.In 25 clear-cut stands 6–12 years old, the average cover of vascular plants was 54% and did not change significantly during the sampled age interval. Cover of tree 'regeneration' (immature size classes) was 5%, increasing slowly, and codominated by lodgepole pine and aspen (Populustremuloides Michx.). Shrub cover was also 5% and dominated by prickly rose (Rosaacicularis Lindl.). Herb – dwarf shrub cover was 44% and dominated by nine species of the mature forest. Bryoid cover was 13 %.The density of young trees stabilized within 6 years after clear-cutting, and the above-ground biomass of both pine and aspen increased rapidly during the sampled age interval.An ordination of the clear-cut stands showed that the distribution and abundance of several important plant species were well correlated with soil moisture on two gravimetric sampling dates in summer.A comparison of dominance–diversity curves and indices for mature and clear-cut stands revealed that the clear-cut community was richer in vascular species (100 cf. 57) and had a more even distribution of cover among species.The early stages of secondary succession after clear-cutting and scarification of lodgepole pine forest are discussed.