Investigating the Landscape Scale Carbon Implications of 100 Years of Land Management in the Sooke Lake Water Supply Watershed, Victoria, British Columbia
Investigating the Landscape Scale Carbon Implications of 100 Years of Land Management in the Sooke Lake Water Supply Watershed, Victoria, British Columbia
Previously Published Material: Approximately 50% of this research was presented at the AGU 2014 Fall Meeting December 15-19 in San Francisco. Specifically, the baseline carbon budget and dissolved organic carbon parameterization was presented in poster form. This research has not yet been submitted to a scientific journal.
Abstract ID#: 33479
English Abstract:
To address how natural disturbance, forest harvest, and deforestation from reservoir creation affect landscape-level carbon (C) budgets, a retrospective C budget for the 8595 ha Sooke watershed from 1911-2012 was developed using historic spatial inventory and disturbance data. A baseline C budget was prepared using a spatially-explicit version of the C Budget Model-Canadian Forest Sector (CBM-CFS3), an inventory-based model used to simulate forest C dynamics at multiple scales. To examine management effects, two alternate management scenario C budgets were developed in CBM-CFS3: (S1) no reservoir raising (flooding) or sustained yield forestry and (S2) reservoir raising but no sustained forestry. In 1911 the watershed was dominated by mature/old Douglas-fir forests with aboveground biomass C (ABC) of 262 Mg C/ha and net biome production (NBP) of 0.38 Mg C/ha/yr. Successive dams were built, land cleared, and reservoir area expanded from 370 to 450 ha in 1915, 610 ha in 1970, 670 ha in 1980 and 810 ha in 2002. Early fires and logging from 1911-1953 were followed by sustained forestry from 1954 -1998, with a minimum ABC of 148 Mg C/ha in 1991. By 2012 ABC (177 Mg C/ha) had increased though still less than in 1910. Cumulative NBP (ƩNBP) for the baseline recovered from a low of -167 Mg C/ha in 1994 to -142 Mg C/ha in 2012. In contrast, the minimum ƩNBP for S1 was -85 Mg C/ha in 1956 and recovered to -35 Mg C/ha by 2012. Minimum ƩNBP for S2 was also in 1956 (-88 Mg C/ha) and increased to -49 Mg C/ha by 2012. Even with elimination of sustained forestry, deforestation alone did temper the ability of the landscape to recoup C losses earlier in the century. Over 100 years in the baseline run, 2430 ha of forest was cut and replanted, 640 ha deforested and 882,746 Mg C exported as harvested wood products (HWP). Total HWP export was decreased by 46% and 60% in S2 and S1, respectively, from the baseline. The effects of accounting for storage of C in HWP will be discussed.