祁连山3种典型生态系统土壤微生物活性和生物量碳氮含量

 测定分析了祁连山高寒草甸、山地森林和干草原土壤中微生物活性、生物量碳氮含量。结果显示：就土壤微生物生物量碳含量，森林比干草原和高寒草甸中分别高60%和120%以上，干草原比高寒草甸中高40%以上(p<0.05)。就土壤微生物生物量氮含量，0～5 cm土层，森林比高寒草甸和干草原中分别高64%和111%以上，高寒草甸比干草原中高29%；5～15 cm土层，森林比干草原和高寒草甸中分别高7%和191%以上，干草原比高寒草甸中高171% 以上(p<0.05)。森林和干草原中土壤微生物生物量碳比例比高寒草甸中高32%以上，0～5和5～15 cm土层，森林和干草原中土壤微生物生物量氮比例比高寒草甸中高150%以上（p<0.05）。就土壤微生物活性，0～5和5～15 cm土层，森林和高寒草甸比干草原中高26%以上；15～35 cm土层，森林比干草原和高寒草甸中高28%以上 (p<0.05)。土壤微生物生物量碳氮含量与有机碳含量及微生物生物量氮含量和比例与微生物生物量碳含量和比例呈现正相关（r²>0.30，p<0.000 1）。土壤微生物生物量氮含量、微生物生物量碳氮含量比例、微生物活性与土壤pH值呈显著负相关,土壤微生物生物量碳氮含量及其比例、微生物活性与土壤湿度呈正相关。说明祁连山3种生态系统土壤中微生物生物量和活性受气候要素、植被、有机碳、pH值和湿度等因素 的共同影响。

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

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.