Biogeosciences

An Interactive Open Access Journal of the European Geosciences Union

| Contact |
Volumes and Issues  Contents of Issue 6  Special Issue  
Biogeosciences Discuss., 4, 4507-4538, 2007
www.biogeosciences-discuss.net/4/4507/2007/
© Author(s) 2007. This work is licensed
under a Creative Commons License.

Wetland succession in a permafrost collapse: interactions between fire and thermokarst

I. H. Myers-Smith1,*, J. W. Harden2, M. Wilmking3, C. C. Fuller2, A. D. McGuire4, and F. S. Chapin III1
1Institute of Arctic Biology, 311 Irving I Bldg., University of Alaska Fairbanks, Fairbanks, Alaska, 99775, USA
2US Geological Survey, 345 Middlefield Rd. MS 962, Menlo Park, California, 94025, USA
3Institute for Botany and Landscape Ecology, Grimmer Strasse 88, Greifswald University, 17487, Greifswald, Germany
4U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, Univ. of Alaska Fairbanks, 214 Irving I Bldg., Univ. of Alaska Fairbanks, Fairbanks, Alaska, 99775, USA
*now at: Department of Biological Sciences, CW 405, Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada

Abstract. To determine the influence of fire and thermokarst in a boreal landscape, we investigated ~600 years of vegetation succession from peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate that succession proceeded from a terrestrial forest to a sedge-dominated wetland over 100 years ago and to a Sphagnum-dominated bog in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing season temperature record from Fairbanks. The concurrent wetland succession and reduced growth of black spruce trees indicates a non-linear ecosystem-level response to a change in regional climate. In 2001, fire was observed coincident with permafrost collapse and resulted in lateral expansion of the bog. These observations and the peat profile suggest that future warming and/or increased fire disturbance could promote permafrost degradation and bog expansion, and increase carbon storage in the collapse; however, the development of drought conditions could reduce the success of black spruce and Sphagnum, decreasing long-term ecosystem carbon storage in the adjacent landscape.

Discussion Paper (PDF, 7606 KB)   Interactive Discussion (Closed, 7 Comments)   Final Revised Paper (BG)

Citation: Myers-Smith, I. H., Harden, J. W., Wilmking, M., Fuller, C. C., McGuire, A. D., and Chapin III, F. S.: Wetland succession in a permafrost collapse: interactions between fire and thermokarst, Biogeosciences Discuss., 4, 4507-4538, 2007.   Bibtex   EndNote   Reference Manager

Search BG


News

Recent Papers