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Acta Prataculturae Sinica ›› 2016, Vol. 25 ›› Issue (11): 25-33.DOI: 10.11686/cyxb2015215

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Changes in organic carbon and nitrogen storage in alpine meadows under different grazing management regimes

LI Wen, CAO Wen-Xia*, SHI Shang-Li, LI Xiao-Long, CHEN Jian-Gang, XU Chang-Lin   

  1. Grassland Science College of Gansu Agricultural University, Grassland Ecosystem Key Laboratory of Ministry of Education, Si-no-U.S. Research Centers for Sustainable Grassland and Livestock Management, Lanzhou 730070, China
  • Received:2015-04-23 Online:2016-11-20 Published:2016-11-20

Abstract: A study has been undertaken to investigate changes in organic carbon and nitrogen storage under different grazing regimes in the alpine meadow ecosystem of the eastern margin of the Qinghai-Tibetan plateau. Organic carbon and nitrogen storage was measured in above-ground biomass, litter, roots and the 0-80 cm soil layer (divided 8 layers, and each layer was 10 cm) at four sites that represent different grazing management regions: non-grazing (NG), grazing rest during the growing stage (RG), traditional grazing (TG) and continuous grazing (CG). The results indicated that organic carbon and nitrogen in the 0-80 cm soil layer, roots, above-ground tissue and litter were significantly higher in NG, RG and TG than in CG. In general, the proportion of organic carbon in the alpine meadow ecosystem was the largest in soils (88.859%-98.242%), followed by roots (1.563%-8.742%), vegetation (0.172%-1.430%) and litter (0.022%-0.969%); similarly, the proportion of nitrogen was the largest in soils (97.331%-99.633%), followed by roots (0.316%-2.071%), vegetation (0.047%-0.442%) and litter (0.003%-0.157%). There were obvious differences in the vertical distributions of soil organic carbon and nitrogen storage under the four grazing regimes, with these differences mainly affecting the 0-40 cm layer and with no significant effect on deeper layers. Organic carbon and nitrogen storage was mainly distributed in the 0-40 cm layer, with grazing tending to move this storage to deeper layers. NG, RG and TG significantly increased storage in the alpine meadow ecosystem, while CG significantly reduced storage and was associated with a loss of carbon and nitrogen. Non-grazing and seasonal rest grazing can thus contribute to achieving carbon and nitrogen sinks on the eastern margin of the Qinghai-Tibetan Plateau and are important grazing management regimes for this and similar areas.