Carbon stocks of western redcedar and western hemlock stands in Canada's inland temperate rainforests.

This study was conducted to fill a knowledge gap in forest ecosystem carbon (C) stocks for managed/harvested and unmanaged old-growth stands of Interior Cedar Hemlock (ICH) biogeoclimatic zone forests, also known as Inland Temperate Rainforests' (ITRs), in central British Columbia (BC). Carbon stocks of live tree (with accounting for heart-rot and hollow) and dead organic matter (snag, coarse woody debris, and forest floor excluding mineral soil) were quantified in three study sites designated as ICHwk3 or ICHvk2. The C stocks were evaluated among stands treated with three different harvesting methods: clear-cutting (CC), group retention (GR, 30% retention), group selection (GS, 70% retention), and uncut (UN, 100% retention). Mean total forest C stocks (excluding mineral soil) in old-growth stands were 455 ± 156 Mg C ha⁻¹ (± 95% confidence interval) similar to regional average forest C stocks for the Pacific Northwestern USA, demonstrating the important C reservoirs in this ecosystem despite the high incidence of heart-rot in cedar. Live-tree and dead-organic-matter C stocks accounted for 76 and 24% of the total C, respectively. Tree biomass allometric equations were the largest contributor to total uncertainty in live-tree C stocks. This indicates the need to develop ITR-specific tree allometric equations for more accurate assessment of live-tree C. Old ITRs were found to be vulnerable to intensive harvesting (CC and GR), losing the total C stocks of 78 and 65% below those of uncut old-growth stands. In contrast, low-intensity harvesting (GS) reduced the C stocks of only 13% below those of uncut old-growth stands and thus provides a good compromise between forest harvesting to provide wood products and maintenance of forest C stocks at all sites. High spatial variability observed in the total forest C stock also stresses the importance of recognizing landform-related productivity gradients (i.e., toe slopes) in the old ITRs. In the face of continued greenhouse gas accumulat