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cje ›› 2004, Vol. ›› Issue (6): 25-28.

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Effects of nitrogen supply and demand status of soil and herbage system on vegetation succession and grassland degradation in alpine meadow

CAO Guangmin, WU Qin, LI Dong, HU Qiwu, LI Yuemei, WANG Xi   

  1. Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xi'ning 810001, China
  • Received:2003-12-10 Revised:2004-03-10 Online:2004-12-10

Abstract: Four typical pastures which represented different degradation stage of alpine meadow were selected at Haibei station of alpine meadow ecosystem.Thus,the studies on soil nitrogen supply ability due to its mineralization and herbages' demand for nitrogen were conducted.Consequently,effects of nitrogen supply and demand status of soil and herbage system on vegetation succession and grassland degradation in alpine meadow was discussed.The results showed that during the herbages growing period from May to August,through nitrogen mineralization,soil supplied 15.86 g穖-2.However,with the aggravation of grassland degradation,the dominate population in the communities was succeessed fromGramineae to Gramineae and Cyperaceae,and then to Kobresia,and forb.During the process of succession,the herbages' total demands for nitrogen were 22.86,24.87,37.3 and 14.96g穖-2,respectively.Only at the stage of soil nitrogen supply can meet the demands of herbage's growth.Therefore,nutrient is one of the most important driving factors that lead to vegetation succession and pasture degradation in alpine meadow region.

Key words: Eringonidium graminicola Sundevall, Adonia variegata Goeze, Nabis sinoferus Hsiao, Predation function, Helicoverpa armigera Hubner

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