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Acta Prataculturae Sinica ›› 2011, Vol. 20 ›› Issue (6): 135-142.

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Seasonal dynamics in soil microbial biomass and enzymatic activities under different alpine brushlands of the Eastern Qilian Mountains

YANG Cheng-de1, LONG Rui-jun2, CHEN Xiu-rong1, XU Chang-lin1, XUE Li1   

  1. 1.College of Pratacultural Science, Gansu Agricultural University; Key Laboratory of Grassland Ecosystem (Gansu Agricultural University), Ministry of Education; Sino-U.S. Center for Grazingland Ecosystem Sustainability, Lanzhou 730070, China;
    2.College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
  • Received:2010-09-08 Online:2011-06-25 Published:2011-12-20

Abstract: The soil microbial biomass and enzymatic activities were studied under Rhododendrons alpine brush lands (RB), Salix cupularis alpine brush lands (SB) and Dasiphoru fruticosa alpine brush lands (DB) of the Eastern Qilian Mountains in the Qinghai-Tibetan Plateau, China. The seasonal trend of soil microbial biomass carbon (SMBC) increased significantly from May to July (P<0.05), and then fell significantly from July to September (P<0.05), before increasing again until November across all three sites. However, the soil microbial biomass nitrogen (SMBN) and the soil microbial biomass phosphorus (SMBP) significantly decreased from May to September then increased again after September except that the SMBN under SB decreased from May to November. The seasonal dynamics of SMBC/soil organic matter (SOM), SMBN/soil total nitrogen (STN) and SMBP/soil total phosphorus (STP) showed similar trends to the SMBC, SMBN and SMBP, respectively. The annual mean ratio of SMBC/SMBN was 5.79-10.31: this was higher in the lower than in the upper layer. The maximum was in July and the minimum in September. Urease activities gradually increased from May to July, and then decreased after July across all three sites. The seasonal dynamics of neutral phosphatase activities (NPA) increased from May to July, but significantly (P<0.05) decreased from July to September, and then gradually increased after September at RB. At SB, the NPA gradually increased from May to November while at DB, it increased from May to September, and then decreased after September.

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