Forest dynamics and the application of a natural disturbance-based management model in Duck Mountain Provincial Forest, Manitoba.

摘要

The forest industry has been moving towards the adoption of ecosystem-based forest management techniques to achieve sustainable forest management. Different models have been developed in an attempt to incorporate increasingly diverse management goals. This study utilizes data from a pilot Forest Land Inventory (FLI) (i) to identify major successional pathways in Duck Mountain Provincial Forest of western Manitoba, (ii) to analyze tree species cover variability within each pathway, (iii) to assess the successional variability of forest stands originating from large, catastrophic fires that occurred in the 1880s and 1890s, and (iv) to assess the applicability of the three structural cohort natural disturbance based management (NDBM) model, developed for the mixed boreal forest of Quebec. Cluster analyses were performed to classify the upper forest canopy into 3 major successional pathways: Trembling aspen-white spruce, jack pine-black spruce, and black spruce-eastern larch. Ordination analysis was used to determine the relationship among vegetation, environmental, and structural variables within each major pathway. Results suggested that the FLI environmental variables distinguish well among the three major pathways primarily along a moisture/slope gradient, but explain little of the species and structural variability within each pathway. Forest stands originating from large fires in the 1880s and 1890s were analyzed to assess successional variability within each major pathway. Results showed that despite being of similar age, there was a large amount of variability in structural development, but 2-layered canopies with a continuous to discontinuous upper canopy tended to dominate in these stands. The landscape was then classified into structural cohorts. Globally, 59.5%, 34.5%, and 6.0% of the landscape was in cohort 1, 2, and 3, respectively. The three structural cohort management model was applied to the forest under three different scenarios: (1) the current distribution of cohorts, (2) a 110-year fire cycle (current), and (3) a 60-year fire cycle (pre-European settlement). Results suggest that, in terms of forest structure, the current distribution of cohorts in DMPF is closest to the expected distribution under a 60-year fire cycle. The results are compared to findings in other regions of the mixed boreal forest, and the implications for forest management in DMPF are discussed.