Title: Decomposition of soil organic matter from boreal black spruce forest: environmental and chemical controls
Author: Wickland, Kimberly P.; Neff, Jason C.;
Source: Biogeochemistry 87(1):29-47
Publication Series: Scientific Journal (JRNL)
Description: Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a "Well Drained" site where permafrost was absent, and "Moderately well Drained" and "Poorly Drained" sites where permafrost was present at about 0.5 m depth. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the "Well Drained" site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and several unidentifiable compounds) could account for approximately 44% of the variation in mineralization across all sites under ideal temperature and moisture conditions. Based on our results, changes in temperature and moisture likely have similar, additive effects on in situ soil organic matter (SOM) decomposition across a wide range of black spruce forest systems, while variations in SOM chemistry can lead to significant differences in decomposition rates within and among forest sites.
Keywords: Alaska, boreal forest, decomposition, permafrost, pyrolysis, GC/MS, soil, organic carbon
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Wickland, Kimberly P.;Neff, Jason C. 2007. Decomposition of soil organic matter from boreal black spruce forest: environmental and chemical controls. Biogeochemistry. 87(1): 29-47.
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