SIMULATING CARBON DYNAMICS OF THE BOREAL FOREST IN PUKASKWA NATIONAL-PARK

The development of forests in Pukaskwa National Park, Ontario, Canada, was simulated over 150 years to investigate boreal carbon dynamics an d to test the feasibility of simulating large tracts of heterogeneous boreal forest. Pukaskwa National Park, located on the north shore of L ake Superior, encompasses 1835 km(2) of the Superior Section of the bo real forest. We developed a patch model, called BOPAS (BOreal PAtch Si mulator), to simulate the development of carbon pools as a function of environmental parameters, Using GIS techniques, we divided the park i nto patches defined by a unique combination of forest type, age, clima tic variables, soil type and topography, then used a forest gap model to develop biomass-over-time relationships for each patch type. BOPAS uses these relationships to simulate the development of carbon pools f or trees, moss and litter/humus. We report results for constant climat e, but BOPAS can be easily adapted to changing climate scenarios. Good results were obtained for predictions of carbon storage in trees. The initial value was 3.61 kg C m(-2), which agrees closely with literatu re values. With no disturbance, tree carbon increased to a maximum of 3.97 kg C m(-2) at 30 years then slowly declined. Carbon storage was s tabilized by introducing fire as a disturbance with a return interval of 100 years. Predicted forest floor carbon density, however, was much lower than expected, being less than half that of trees. It was antic ipated to be substantially higher than tree carbon density based on a preliminary survey in the park and values reported in the literature. Published data, however, are very limited in coverage and give such a wide range of values that it was impossible to draw any firm conclusio ns about the validity of the model. BOPAS also showed that the forest floor carbon pool was relatively constant over the timescales of the s imulation, but no published data were available to test this predictio n. In summary, this work has demonstrated the feasibility of the BOPAS approach, but has high-lighted the necessity for more extensive data on forest Boor carbon storage and dynamics.