Chen, Jing M (Department of Geography, University of Toronto, 100 St. George St., Toronto, Ontario, Canada, M5S 3G3; Phone: 416-978-7085; Fax: 416-946-3886; Email: chenj@geog.utoronto.ca)

Mapping Carbon Source and Sink Distributions in Canada’s Forests and Wetlands Resulting from Disturbance and Non-disturbance Effects

Jing M. Chen, Weimin Ju,

In collaboration with several federal government agencies and universities, annual spatial distributions of carbon sources and sinks in Canada’s forests and wetlands at 1 km resolution are computed for the period from 1901 to 1998 using ecosystem models that utilize remote sensing images and gridded climate, soils, and forest inventory data. GIS-based large fire polygons for most regions of Canada are used to develop a remote sensing algorithm for mapping and dating forest burned areas in the 25 years prior to 1998. These mapped and dated burned areas are used in combination with inventory data to produce a complete image of forest stand age in 1998. Empirical NPP-age relationships were used to simulate the annual variations of forest growth and carbon balance in 1 km pixels, each treated as a homogeneous forest stand. Annual CO₂ flux data from five sites were used for model validation. The Integrated Terrestrial Ecosystem Carbon Cycle Model (InTEC) was developed (Chen et al., 2000) for this carbon source and sink mapping in annual time steps. This model is supplemented by a daily model named Boreal Ecosystem Productivity Simulator (BEPS) for detailed simulations in recent years (Liu et al., 2003). InTEC is recently expanded to include aerobic and anaerobic processes in wetlands, so that the total carbon absorption and release by CO₂ and CH₄ gases are also included (Figure 6). Both disturbance (fire, insect, harvest) and non-disturbance (climate, N, CO₂) factors and their interactions are included the model. The significance of these new national statistics of the carbon budgets of Canada’s forests and wetlands will be discussed in comparison with previous results.