Mineralization responses at near-zero temperatures in three alpine soils |
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| Authors: | Amy E Miller Joshua P Schimel James O Sickman Thomas Meixner Allen P Doyle John M Melack |
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| Institution: | (1) Institute for Computational Earth System Science, University of California, Santa Barbara, CA 93106, USA;(2) Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA;(3) Department of Environmental Sciences, University of California, Riverside, CA 92521, USA;(4) Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA;(5) Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309-0450, USA;(6) Present address: National Park Service, 240 West 5th Ave., Anchorage, AK 99501, USA |
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| Abstract: | Cold-season processes are known to contribute substantially to annual carbon (C) and nitrogen (N) budgets in continental high
elevation and high-latitude soils, but their role in more temperate alpine ecosystems has seldom been characterized. We used
a 4-month lab incubation to describe temperature (−2, 0, 5°C) and moisture 50, 90% water-holding capacity (WHC)] effects
on soil C and N dynamics in two wet and one dry meadow soil from the Sierra Nevada, California. The soils varied in their
capacity to process N at and below 0°C. Only the dry meadow soil mineralized N at −2°C, but the wet meadow soils switched
from net N consumption at −2°C to net N mineralization at temperatures ≥0°C. When the latter soils were incubated at −2°C
at either moisture level (50 or 90% WHC), net NO3
− production decreased even as NH4
+ continued to accumulate. The same pattern occurred in saturated (90% WHC) soils at warmer temperatures (≥0°C), suggesting
that dissimilatory processes could control N cycling in these soils when they are frozen. |
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| Keywords: | Cold-season processes Nitrogen Nitrate consumption Ammonification Soil moisture Sierra Nevada |
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