Secondary vegetation and floristic succession within a boreal aspen (Populus tremuloides Michx.) clearcut

Abstract

The composition and abundance of vascular plants within a boreal Populus tremuloides Michx. stand in west-central Alberta were assessed three, five, nine, and 20 years after clearcutting. Rapid re-establishment of Populus tremuloides and other species such as Amelanchier alnifolia (Nutt.) Nutt. ex M. Roemer and Rosa acicularis Lindl. occurred primarily in response to vegetative propagation. Some minor compositional variability occurred among the year 3 plots (n = 88), but they were considered members of the same plant community, with 88% of the plots undergoing similar developmental processes during the course of the study. Some dominant species substantially increased in canopy cover, although most species maintained a relatively consistent level of abundance over time. Floristic richness was similar in year 3 (64 species) and year 20 (62 species) with the survival of 52 initiating species in year 20. The variability in floristic richness included the invasion of 32 species and the extirpation of 34 species. Stand development over a 20-year period best fit a tolerance model of succession because of the rapid development of dominant species, the lack of a major understory composition change, and a similar degree of dominance concentration among species. Understory vegetation growth was constrained by overstory shading.Key words: plant community, tolerance model, secondary succession.