Interactions among temperature, moisture, and oxygen concentrations in controlling decomposition rates in a boreal forest soil
Determining environmental controls on soil organic matter decomposition is of importance for developing models that predict the effects of environmental change on global soil carbon stocks. There is uncertainty about the environmental controls on decomposition rates at temperature and moisture extre...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/14/703/2017/bg-14-703-2017.pdf |
| Summary: | Determining environmental
controls on soil organic matter decomposition is of importance for developing
models that predict the effects of environmental change on global soil carbon
stocks. There is uncertainty about the environmental controls on
decomposition rates at temperature and moisture extremes, particularly at
high water content levels and high temperatures. It is uncertain whether
observed declines in decomposition rates at high temperatures are due to
declines in the heat capacity of extracellular enzymes as predicted by
thermodynamic theory, or due to simultaneous declines in soil moisture. It is
also uncertain whether oxygen limits decomposition rates at high water
contents. Here we present the results of a full factorial experiment using
organic soils from a boreal forest incubated at high temperatures (25 and
35 °C), a wide range of water-filled pore space (WFPS; 15, 30, 60,
90 %), and contrasting oxygen concentrations (1 and 20 %). We found
support for the hypothesis that decomposition rates are high at high
temperatures, provided that enough moisture and oxygen are available for
decomposition. Furthermore, we found that decomposition rates are mostly
limited by oxygen concentrations at high moisture levels; even at 90 %
WFPS, decomposition proceeded at high rates in the presence of oxygen. Our
results suggest an important degree of interaction among temperature,
moisture, and oxygen in determining decomposition rates at the soil core
scale. |
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| ISSN: | 1726-4170 1726-4189 |