Chin J Plan Ecolo ›› 2008, Vol. 32 ›› Issue (2): 465-476.DOI: 10.3773/j.issn.1005-264x.2008.02.026

• Research Articles • Previous Articles     Next Articles

SOIL MICROBIAL ACTIVITY AND BIOMASS C AND N CONTENT IN THREE TYPICAL ECOSYSTEMS IN QILIAN MOUNTAINS, CHINA

WU Jian-Guo1; AI Li1,2   

  1. 1Chinese Academy of Environmental Sciences, Beijing, 100012, China; 2 University of Science and Technology Beijing, Beijing 100083, China
  • Online:2008-03-30 Published:2008-03-30
  • Contact: WU Jian-Guo

Abstract: Aims Our objectives were to measure the soil microbial biomass carbon (SMB C), soil microbial biomass nitrogen (SMB N) content and soil microbial activity, and determine the relationship between these parameters and other soil properties (including organic carbon, total nitrogen content and water content) in montane forest (dominated by Picea crassifolia), steppe and alpine meadow ecosystems in Qi Lian Mountains, China. 
Methods We measured SMB C and SMB N content using fumigation-incubation method and soil microbial activity using substrate-induced respiration.
Important findings The SMB C content under forest was 60% and 120% higher than under steppe and alpine meadow, respectively, and it was 40% higher under steppe than alpine meadow. The SMB N content was 64% and 111% higher in 0-5 cm soil depth under forest than alpine meadow and steppe, respectively, and it was 29% higher under alpine meadow than steppe. Also, it was 7% and 191% higher in 5-15 cm soil depth under forest than steppe and alpine meadow, respectively, and it was 171% higher under steppe than alpine meadow (p<0.05). The ratio SMB C (SMB C-to-SOC (Soil organic carbon), 0.4%-2.8%) was 32% higher under forest and steppe than alpine meadow, and the ratio of SMB N (SMB N-to-total soil N, 0.5%-2.8%) in 0-5 and 5-15 cm soil depths was 150% higher under forest and steppe than alpine meadow (p<0.05). Soil microbial activity in 0-5 or 5-15 cm soil depth was 26% higher under forest or alpine meadow than steppe, and in 15-35 cm soil depth it was 28% higher under forest than steppe and alpine meadow (p<0.05). The SMB C and SMB N content was positively correlated with SOC content, and the SMB N content or its ratio was also positively correlated with the SMB C content and its ratio (r2>0.30, p<0.000 1). The SMB N content, SMB C ratio, SMB N ratio and microbial activity were significantly negatively correlated with soil pH. The SMB C content, SMB N content and their ratio and microbial activity were positively correlated with soil water content.