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The weak effects of fencing on ecosystem respiration, CH4, and N2O fluxes in a Tibetan alpine meadow during the growing season
Received:June 29, 2017    Click here to download the full text
Citation of this paper:YiGang Hu,ZhenHua Zhang,ShiPing Wang,ZhiShan Zhang,Yang Zhao,ZengRu Wang,2017.The weak effects of fencing on ecosystem respiration, CH4, and N2O fluxes in a Tibetan alpine meadow during the growing season.Sciences in Cold and Arid Regions,9(6):554~567.
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Author NameAffiliationE-mail
YiGang Hu Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China huyig@lzb.ac.cn 
ZhenHua Zhang Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai 810008, China  
ShiPing Wang Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing 100101, China wangsp@itpcas.ac.cn 
ZhiShan Zhang Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China  
Yang Zhao Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China  
ZengRu Wang Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China  
 
Abstract:Fencing is the most common land-management practice to protect grassland degradation from livestock overgrazing on the Tibetan Plateau. However, it is unclear whether fencing reduces CO2, CH4, and N2O emission. Here, we selected four vegetation types of alpine meadow (graminoid, shrub, forb, and sparse vegetation) to determine fencing effects on ecosystem respiration (Re), CH4, and N2O fluxes during the growing season. Despite increased average monthly ecosystem respiration (Re) for fenced graminoid vegetation at the end of the growing season, there was no significant difference between grazing and fencing across all vegetation types. Fencing significantly reduced average CH4 uptake by about 50% in 2008 only for forb vegetation and increased average N2O release for graminoid vegetation by 38% and 48% in 2008 and 2009, respectively. Temperature, moisture, total organic carbon, C/N, nitrate, ammonia, and/or bulk density of soil, as well as above- and belowground biomass, explained 19%~71% and 6%~33% of variation in daily and average Re and CH4 fluxes across all vegetation types, while soil-bulk density explained 27% of variation in average N2O fluxes. Stepwise regression showed that soil temperature and soil moisture controlled average Re, while soil moisture and bulk density controlled average CH4 fluxes. These results indicate that abiotic factors control Re, CH4, and N2O fluxes; and grazing exclusion has little effect on reducing their emission—implying that climatic change rather than grazing may have a more important influence on the budgets of Re and CH4 for the Tibetan alpine meadow during the growing season.
keywords:fencing  ecosystem respiration  methane  nitrous oxide  Tibetan alpine meadow
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