| Isozyme analysis was used to assess the effects of current forest management practices on the genetic diversity of three understory plant species, Cornus canadensis, Maianthemum canadense and Ribes glandulosum. Populations were sampled in natural stands originating after heavy spruce budworm feeding, and from clearcut stands that were either left to regenerate naturally or planted with black spruce. A chronosequence analysis covering a twenty year period was used to examine changes in genetic diversity over time after human-caused disturbance. Results from thirteen putative loci for C. canadensis and R. glandulosum, and seventeen putative loci for M. canadense indicate that generalizations about genetic diversity of plant populations based on identifiable life history characteristics and ecological traits should be applied with caution to individual species. Overall, C. canadensis was the most variable, followed by M. canadense. R. glandulosum had the lowest values for every estimated diversity measure. The differences among disturbance types and age classes were not statistically significant. However, clear and repeated trends within species indicated that genetic diversity response to major disturbance varies by species. |
