Simulated predictions of forest dynamics in Fundy National Park, Canada

Abstract

Ecosystems in recently established parks and wilderness areas commonly show their dynamic nature through rapid changes after protection from major human intervention. Within Fundy National Park, located in eastern Canada and designated in 1948, forested stands had been selectively harvested for 150 years and insect defoliation had killed large areas of mature balsam fir trees in the late 1970s and early 1980s. Our objective was to develop long-term quantitative predictions of change in forest composition as an aid to park managers. A dynamic simulation model was calibrated to the climatic conditions and then validated over a short-term forest species-composition data-set that had been collected on permanent sample plots. The model appeared to mimic these stand dynamics with sufficient accuracy that permanent sample-plot compositions were simulated for 150 years into the future. Most of the recently disturbed forest stands in Fundy National Park are relatively young compared to the life-span of the major tree species. Thus, for most of the stands over the short term (25 years), it is predicted that there will be minor changes in stand composition. Over a greater time-period, almost all stands will show a decline in total biomass and in the number of stems. Only those permanent plots in warmer habitats that support sugar maple will maintain species composition. All other forest compositions showed a more dynamic nature. Stands with dominant species such as black spruce, white birch, and white spruce will tend to decline so that they become co-dominant with other species, particularly red spruce, or more commonly, balsam fir. Permanent sample plots that now contain red spruce will tend to remain dominated by red spruce, but balsam fir will become an increasingly important component, especially in terms of the number of stems. Simulation approaches such as outlined here are useful to the park manager in that they provide a long-term quantitative framework of forest composition change. The simulations suggest which major forest types will have stable composition and which will change rapidly. If these predictions are unacceptable to the park managers in light of other management concerns, then a range of interventions could be simulated, and the most acceptable chosen and then implemented. Continuing field-monitoring is necessary to ensure the validity of the simulation model.