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Soil carbon distribution in Alaska in relation to soil-forming factorsAuthor(s): Kristofer D. Johnson; Jennifer Harden; A. David McGuire; Norman B. Bliss; James G. Bockheim; Mark Clark; Teresa Nettleton-Hollingsworth; M. Torre Jorgenson; Evan S. Kane; Michelle Mack; Johathan ODonnell; Chien-Lu Ping; Edward A.G. Schuur; Merritt R. Turetsky; David W. Valentine
Source: Geoderma. 167-168: 71-84
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
PDF: Download Publication (1.19 MB)
DescriptionThe direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-order assessment of data gaps and spatial distributions of SOC was conducted from a recently compiled soil carbon database. Temperature and landform type were the dominant controls on SOC distribution for selected ecoregions. Mean SOC pools (to a depth of 1-m) varied by three, seven and ten-fold across ecoregion, landform, and ecosystem types, respectively. Climate interactions with landform type and SOC were greatest in the uplands. For upland SOC there was a six-fold non-linear increase in SOC with latitude (i.e., temperature) where SOC was lowest in the Intermontane Boreal compared to the Arctic Tundra and Coastal Rainforest. Additionally, in upland systems mineral SOC pools decreased as climate became more continental, suggesting that the lower productivity, higher decomposition rates and fire activity, common in continental climates, interacted to reduce mineral SOC. For lowland systems, in contrast, these interactions and their impacts on SOC were muted or absent making SOC in these environments more comparable across latitudes. Thus, the magnitudes of SOC change across temperature gradients were non-uniform and depended on landform type. Additional factors that appeared to be related to SOC distribution within ecoregions included stand age, aspect, and permafrost presence or absence in black spruce stands. Overall, these results indicate the influence of major interactions between temperature-controlled decomposition and topography on SOC in high-latitude systems. However, there remains a need for more SOC data from wetlands and boreal-region permafrost soils, especially at depths > 1 m in order to fully understand the effects of climate on soil carbon in Alaska.
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CitationJohnson, Kristofer D.; Harden, Jennifer; McGuire, A. David; Bliss, Norman B.; Bockheim, James G.; Clark, Mark; Nettleton-Hollingsworth, Teresa; Jorgenson, M. Torre; Kane, Evan S.; Mack, Michelle; O'Donnell, Jonathan; Ping, Chien-Lu; Schuur, Edward A.G.; Turetsky, Merritt R.; Valentine, David W. 2011. Soil carbon distribution in Alaska in relation to soil-forming factors. Geoderma. 167-168: 71-84.
Keywordssoil carbon, soil-forming factors, Arctic, boreal, permafrost, Alaska
- Modeling the effects of fire severity and climate warming on active layer thickness and soil carbon storage of black spruce forests across the landscape in interior Alaska
- Decomposition of soil organic matter from boreal black spruce forest: environmental and chemical controls
- The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: implications for post-thaw carbon loss
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