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TitleSpatial Distribution of Carbon Sinks and Sources in Canada's Forests Based on Remote Sensing, Climate, Inventory and Tower Flux Data
AuthorChen, J M; Chen, WORCID logo; Liu, J; Cihlar, J; Ou, Y; Pavlic, G; Price, D; Amiro, B D; Frofymow, T; Black, T A; McCaughey, H
SourceInternational Science Conference: The Role of Boreal Forests and Forestry in the Global Carbon Budge, Edmonton, Alberta, Canada, 8-12 May; 2000.
Alt SeriesEarth Sciences Sector, Contribution Series 20042854
AbstractIn order to determine the role of Canada's forests in the global carbon balance, it is necessary to map the spatial distribution of carbon sinks and sources and to understand their temporal dynamics. To this end, we will provide an overview of our methods for mapping leaf area index (LAI), landcover, net primary productivity (NPP), fire scar age, and net ecosystem productivity (NEP) using satellite, climate, inventory and tower flux data. An optical instrument recently developed at CCRS has become a new international standard for ground-based measurements of LAI. A process-based daily canopy NPP model with sunlit/shaded leaf separation was validated using two-level CO2 tower flux data. This new model avoids problems of widely-used big-leaf models for regional applications. Spatial forestry inventory data were co-registered with images from the VEGETATION sensor, and an algorithm for detecting fire scar age up to 50 years was developed. An Integrated Terrestrial Ecosystem Carbon Budget Model (InTEC) was developed to describe the long-term effects of disturbance (fire, insect, harvest) and non-disturbance (climate warming, CO2 concentration, N deposition) on forest carbon cycle and to simulate post-disturbance dynamics of various carbon pools in vegetation and soil. The NPP-age relationship derived from InTEC was validated using inventory data. In mapping NEP, gridded half degree climate data for the last 100 years were bi-linearly interpolated to each pixel at 1 km resolution, and NPP in 1994 and stand age information were used. A 1200 km x 1200 km NEP map covering most of Saskatchewan and Manitoba was compared against the tower flux data acquired in 1994-1996 during Boreal Ecosystem-Atmospheric Study (BOREAS). Using the same methodology, Canada-wide NEP maps were produced, showing south-north gradients in the sink/source strength in addition to large spatial variability. These maps are to be validated using tower flux and soil respiration data currently being acquired in different regions of Canada. Problems, new data requirements and directions for improvement will be discussed.

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