期刊
SOIL BIOLOGY & BIOCHEMISTRY
卷 58, 期 -, 页码 50-60出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2012.10.032
关键词
Boreal; Fen; Climate change; Dissolved organic carbon; Peat; Carbon cycle; Nitrogen cycle
类别
资金
- National Science Foundation [DEB-0425328]
- National Science Foundation
- Environmental Protection Agency
- Center for Water Sciences
- Carlsberg foundation
- NSF [DEB-0423442]
- USDA Forest Service [PNWOHV11261952-231]
- Direct For Biological Sciences
- Division Of Environmental Biology [1026415, 0955713, 0955341] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [830997] Funding Source: National Science Foundation
To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 +/- 0.9 mu mol C g(-1) d(-1)) was as high as aerobic CO2 production potential (10.6 +/- 1.5 mu mol C g(-1) d(-1)), while CH4 production was low (mean of 7.8 +/- 1.5 nmol C g(-1) d(-1)). Denitrification enzyme activity indicated a very high denitrification potential (197 +/- 23 mu g N g(-1) d(-1)), but net NO3- reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances of denitrifier genes (nirK and nosZ) did not change across water table treatments. SO42- reduction also did not appear to be an important pathway for anaerobic CO2 production. The net accumulation of acetate and formate as decomposition end products in the raised water table treatment suggested that fermentation was a significant pathway for carbon mineralization, even in the presence of NOT. Dissolved organic carbon (DOC) concentrations were the strongest predictors of potential anaerobic and aerobic CO2 production. Across all water table treatments, the CO2:CH4 ratio increased with initial DOC leachate concentrations. While the field water table treatment did not have a significant effect on mean CO2 or CH4 production potential, the CO2:CH4 ratio was highest in shallow peat incubations from the drained treatment. These data suggest that with continued drying or with a more variable water table, anaerobic CO2 production may be favored over CH4 production in this rich fen. Future research examining the potential for dissolved organic substances to facilitate anaerobic respiration, or alternative redox processes that limit the effectiveness of organic acids as substrates in anaerobic metabolism, would help explain additional uncertainty concerning carbon mineralization in this system. Published by Elsevier Ltd.
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