Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Environmental Research Letters

DOI:https://doi.org/10.1088/1748-9326/8/3/035028· OSTI ID:1095721

Johnson, Kristopher D ^[1]; Harden, Jennifer ^[2]; McGuire, A. David ^[3]; Clark, Mark ^[4]; Yuan, Fengming ^[5]; Finley, Andrew ^[6]

---

1. University of Alaska, Fairbanks
2. United States Geological Service (USGS), Menlo Park
3. University of Alaska
4. United Stated Department of Agriculture (USDA), Natural Resources Conservation Service
5. ORNL
6. Michigan State University, East Lansing

Permafrost is tightly coupled to the organic layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence (PF) and organic layer thickness (OLT) in more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between PF, OLT, and other topographic factors were investigated using structural equation modeling in a multi-group analysis. Groups were defined by slope, soil texture type, and shallow v. deep organic layers. Permafrost probability sharply increased by 0.32 for every 10-cm OLT increase in shallow OLT soils (OLTs) due to an insulation effect, but PF decreased in deep OLT soils (OLTd) by 0.06 for every 10-cm increase. As temperature warmed, sandy soils varied little in PF or OLT, but PF in loamy and sandy soils decreased substantially. The change in OLT was more heterogeneous across soil types in some there was no change while in others OLTs soils thinned and/or OLTd soils thickened as temperature warmed. Furthermore, the rate of thickening with warming for OLTd soils was on average almost 4 times greater than the rate of thinning for OLTs soils across all soil types. If soils follow a trajectory of warming that mimics the spatial gradients found today, then heterogeneities of permafrost degradation and organic layer thinning and thickening should be considered in the regional carbon balance.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1095721
• Journal Information: Environmental Research Letters, Vol. 8, Issue 3; ISSN 1748-9326
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English