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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D1, 8147, doi:10.1029/2001JD001244, 2003

Modeling soil thermal and carbon dynamics of a fire chronosequence in interior Alaska

Q. Zhuang

Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, USA


A. D. McGuire

U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, Fairbanks, Alaska, USA


K. P. O'Neill

Forest Inventory & Analysis, North Central Research Station, USDA Forest Service, St. Paul, Minnesota, USA


J. W. Harden

U.S. Geological Survey ms 962, Menlo Park, California, USA


V. E. Romanovsky

Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA


J. Yarie

Department of Forest Science, University of Alaska Fairbanks, Fairbanks, Alaska, USA


Abstract

In this study, the dynamics of soil thermal, hydrologic, and ecosystem processes were coupled to project how the carbon budgets of boreal forests will respond to changes in atmospheric CO2, climate, and fire disturbance. The ability of the model to simulate gross primary production and ecosystem respiration was verified for a mature black spruce ecosystem in Canada, the age-dependent pattern of the simulated vegetation carbon was verified with inventory data on aboveground growth of Alaskan black spruce forests, and the model was applied to a postfire chronosequence in interior Alaska. The comparison between the simulated soil temperature and field-based estimates during the growing season (May to September) of 1997 revealed that the model was able to accurately simulate monthly temperatures at 10 cm (R > 0.93) for control and burned stands of the fire chronosequence. Similarly, the simulated and field-based estimates of soil respiration for control and burned stands were correlated (R = 0.84 and 0.74 for control and burned stands, respectively). The simulated and observed decadal to century-scale dynamics of soil temperature and carbon dynamics, which are represented by mean monthly values of these variables during the growing season, were correlated among stands (R = 0.93 and 0.71 for soil temperature at 20- and 10-cm depths, R = 0.95 and 0.91 for soil respiration and soil carbon, respectively). Sensitivity analyses indicate that along with differences in fire and climate history a number of other factors influence the response of carbon dynamics to fire disturbance. These factors include nitrogen fixation, the growth of moss, changes in the depth of the organic layer, soil drainage, and fire severity.

Published 14 December 2002.

Index Terms: 1615 Global Change: Biogeochemical processes (4805); 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0330 Atmospheric Composition and Structure: Geochemical cycles.

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Citation: Zhuang, Q., A. D. McGuire, K. P. O'Neill, J. W. Harden, V. E. Romanovsky, and J. Yarie (2002), Modeling soil thermal and carbon dynamics of a fire chronosequence in interior Alaska, J. Geophys. Res., 107, 8147, doi:10.1029/2001JD001244, [printed 108(D1), 2003].