Soil Respiration in the Cold Desert Environment of the Colorado Plateau (USA): Abiotic Regulators and Thresholds |
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Authors: | Daniel P Fernandez Jason C Neff Jayne Belnap Richard L Reynolds |
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Institution: | (1) Environmental Studies, University of Colorado at Boulder, CB 397, Boulder, CO 80309, USA;(2) U.S. Geological Survey, Denver Federal Center, Denver, CO 80225, USA;(3) Geological Sciences and Environmental Studies, University of Colorado at Boulder, CB 399, Boulder, CO 80309, USA;(4) Southwest Biological Science Center, U.S. Geological Survey, Resource Blvd, Moab, UT 84532, USA |
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Abstract: | Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems,
which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration
regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding
about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth
measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature,
organic carbon, and nitrogen influence soil respiration and examined whether the inverse-texture hypothesis applies to decomposition.
Within our study site, the effect of texture on moisture, as described by the inverse texture hypothesis, was evident, but
its effect on decomposition was not. Our results show temperature and moisture to be the dominant abiotic controls of soil
respiration. Specifically, temporal offsets in temperature and moisture conditions appear to have a strong control on soil
respiration, with the highest fluxes occurring in spring when temperature and moisture were favorable. These temporal offsets
resulted in decomposition rates that were controlled by soil moisture and temperature thresholds. The highest fluxes of CO2 occurred when soil temperature was between 10 and 16 °C and volumetric soil moisture was greater than 10%. Decomposition-cloth
results, which integrate decomposition processes across several months, support the soil-respiration results and further illustrate
the seasonal patterns of high respiration rates during spring and low rates during summer and fall. Results from this study
suggest that the parameters used to predict soil respiration in mesic ecosystems likely do not apply in cold-desert environments. |
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Keywords: | Cold desert Regression tree Soil carbon Soil respiration |
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