TY - JOUR
T1 - Soil carbon distribution in Alaska in relation to soil-forming factors
AU - Johnson, Kristofer D.
AU - Harden, Jennifer
AU - McGuire, A. David
AU - Bliss, Norman B.
AU - Bockheim, James G.
AU - Clark, Mark
AU - Nettleton-Hollingsworth, Teresa
AU - Jorgenson, M. Torre
AU - Kane, Evan S.
AU - Mack, Michelle
AU - O'Donnell, Jonathan
AU - Ping, Chien Lu
AU - Schuur, Edward A.G.
AU - Turetsky, Merritt R.
AU - Valentine, David W.
N1 - Funding Information:
This assessment, and the workshop which led to the creation of the soil carbon database used in the assessment, was sponsored by the U.S. Geological Survey funded research on “Assessing the Role of Deep Soil Organic Carbon in Interior Alaska: Data, Models, and Spatial/Temporal Dynamics”. The help of Deb Agarwal and Catharine Van Ingen from Lawrence Berkeley National Labs and Microsoft Research were essential for the creation and logistical support of the soil carbon database. We also acknowledge the very helpful reviews given by Bronwen Wang, Shuguang Liu, Ingeborg Callesen and one anonymous reviewer.
PY - 2011/11
Y1 - 2011/11
N2 - The 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.
AB - The 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.
KW - Alaska
KW - Arctic
KW - Boreal
KW - Permafrost
KW - Soil carbon
KW - Soil forming factors
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U2 - 10.1016/j.geoderma.2011.10.006
DO - 10.1016/j.geoderma.2011.10.006
M3 - Article
AN - SCOPUS:80055044410
SN - 0016-7061
VL - 167-168
SP - 71
EP - 84
JO - Geoderma
JF - Geoderma
ER -