The Impact of Black Spruce (Picea mariana) Plantation on Carbon Exchange in a Cutover Peatland in Western Canada

Northern peatlands are sinks for atmospheric carbon (C), but peat extraction converts these ecosystems to C sources. Due to a dry regional climate, undisturbed bog peatlands in western Canada often have a tree cover of Picea mariana (Mill.) B.S.P. Thus, coniferous forest plantation may be an appropriate land-use for cutover peatlands. This study determined the effect of a seven-year-old P. mariana plantation on C balance of a cutover peatland. We measured C stored in P. mariana biomass and carbon dioxide (CO2) and methane (CH4) fluxes from bare peat at each of four fertilizer doses. Carbon stored in biomass of Betula papyrifera (March.) that had spontaneously colonized the post-fertilized site was also determined. Given that the water table remained very deep, and that the Sphagnum-moss/ericaceous shrub peat-accumulating vegetation was not present, the site remained a source of C when only the planted P. mariana trees were considered, primarily in the form of CO2 emissions by soil respiration. However, C accumulation in trees, including B. papyrifera biomass resulted in a net C sink in fertilized plots. Results from this study indicate that tree plantation on cutover peatland results may be a suitable land management strategy on sites difficult to effectively rewet.

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