Sciences in Cold and Arid Regions ›› 2017, Vol. 9 ›› Issue (6): 554–567.doi: 10.3724/SP.J.1226.2017.00554

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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

YiGang Hu1, ZhenHua Zhang2, ShiPing Wang3,4, ZhiShan Zhang1, Yang Zhao1, ZengRu Wang1   

  1. 1. Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;
    2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai 810008, China;
    3. Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;
    4. CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing 100101, China
  • 收稿日期:2017-06-29 出版日期:2017-12-01 发布日期:2018-11-23
  • 通讯作者: YiGang Hu, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences. No. 320, West Donggang Road, Lanzhou, Gansu 730000, China. Tel: +86-931-4967173, +86-10-84097096; E-mail:huyig@lzb.ac.cn; ShiPing Wang,wangsp@itpcas.ac.cn E-mail:huyig@lzb.ac.cn;wangsp@itpcas.ac.cn
  • 基金资助:
    We thank two anonymous reviewers and the editor for their constructive comments and suggestions to improve this manuscript. This work was financially supported by the Natural Science Foundation Committee of China (41230750 and 41101081), Key Program of the Chinese Academy of Sciences (KFZD-SW-312) and the "National Key Research and Development Program of China" (2016YFC0501802).

The weak effects of fencing on ecosystem respiration, CH4, and N2O fluxes in a Tibetan alpine meadow during the growing season

YiGang Hu1, ZhenHua Zhang2, ShiPing Wang3,4, ZhiShan Zhang1, Yang Zhao1, ZengRu Wang1   

  1. 1. Shapotou Desert Experiment and Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;
    2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai 810008, China;
    3. Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;
    4. CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing 100101, China
  • Received:2017-06-29 Online:2017-12-01 Published:2018-11-23
  • Contact: YiGang Hu, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences. No. 320, West Donggang Road, Lanzhou, Gansu 730000, China. Tel: +86-931-4967173, +86-10-84097096; E-mail:huyig@lzb.ac.cn; ShiPing Wang,wangsp@itpcas.ac.cn E-mail:huyig@lzb.ac.cn;wangsp@itpcas.ac.cn
  • Supported by:
    We thank two anonymous reviewers and the editor for their constructive comments and suggestions to improve this manuscript. This work was financially supported by the Natural Science Foundation Committee of China (41230750 and 41101081), Key Program of the Chinese Academy of Sciences (KFZD-SW-312) and the "National Key Research and Development Program of China" (2016YFC0501802).

摘要: 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.

关键词: fencing, ecosystem respiration, methane, nitrous oxide, Tibetan alpine meadow

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.

Key words: fencing, ecosystem respiration, methane, nitrous oxide, Tibetan alpine meadow

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