A Current and Retrospective Landscape-Level C Budget for the Fluxnet-Canada Coastal British Columbia Station (Oyster River).
Abstract
A retrospective carbon (C ) budget for the Fluxnet-Canada coastal BC Station (5 x 5 km Oyster River Area) for the period 1920 to 2005 was developed using the spatially-explicit version of the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). CBM-CFS3 is an inventory-based C budget modeling tool that has been used to simulate forest C dynamics at national, regional, and operational scales. A current (circa 2000) forest inventory map for the Oyster River Area was compiled using data provided by forest companies (TimberWest and Island Timberlands). This inventory was overlaid with historic disturbance maps and orthophotographs to generate a coverage of forest cover polygons with unique disturbance histories. A 1920 timber cruise map was then used to help estimate the volume, cover type, and age of the forest in each polygon in 1920. Data were loaded into the CBM-CFS3 initialization routine and the model was then used to simulate the forest dynamics and C budget for the 85-year period. The C budget of the Oyster River Area is strongly tied to its disturbance history. In 1920, old-growth forest covered the majority of the study area and net C flux was neutral or small. In the 1930's and 40's, ground fires, clear-cut harvesting (using railroad logging), and slash burning resulted in a significant loss of biomass C and a substantial flux of C into dead organic matter, the atmosphere, and wood product pools (area net average C loss 5 - 20 Mg C/ha/yr). A gradual recovery of ecosystem C stocks followed this period of high disturbance activity but the area remained a significant C source, and did not become a net C sink until well into the 1950's. From 1960 through 1987 disturbance was minimal and the area remained a C sink (area average net uptake 2 - 6 Mg C/ha/yr). As harvesting of the second-growth forest began in the late 1980's, the C budget of the area was once again dominated by disturbances, albeit buffered by ongoing C uptake by living biomass in the residual, undisturbed forest. To evaluate the CBM-CFS3 estimates and improve our understanding, future work is planned to compare model estimates with measurements of C fluxes in two stands with flux towers and of ground plot C stocks in those same and other stands. Comparisons are underway with several physiological-based models to examine how variation in climate and atmospheric CO2 levels over this historical period might change the estimated landscape C budget
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.B51C0331T
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0793;
- 1615;
- 4805;
- 0428 Carbon cycling (4806)