关键词: 高寒土壤, 微生物生物量碳, 土壤活性有机碳, 海拔梯度, 季节动态

Abstract: [Objective] The aim of the study was to determine seasonal dynamics of soil microbial biomass carbon (MBC) as affected by altitude in the subalpine-alpine of western Sichuan.[Method] Topsoil cores (0-20cm) were in situ incubated along an altitudinal gradient (3 250-4 098 m).Soil cores were sampled in September,November,March,May and July,respectively. MBC,microbial biomass nitrogen (MBN) and their ratios were analyzed.[Results] During the cold season (from November to March),subalpine-alpine soil MBC in both soil layers kept a high level (1.3g/kg) and decreased with the increase in elevation.While soil MBC at higher altitude were higher than those at lower altitude from May to September.For seasonal variations of soil MBC in different soil depth,MBC were higher in 10-20cm than in 0-10cm at all altitudes during the cold season but the opposite was true in July.MBC in 0-10cm were lower than that in 10-20cm at 3 250mand 3 438min May and September while there was a contrary tendency at high altitude.There were significant differences in MBC/MBN among elevational gradients.The ratios of MBC to MBN in the two soil layers were generally lower than 4at each altitude in September, November and March.However,the values were still lower than 4only at 3 250mand 3 438min both May and July.[Conclusion] There were significant differences in MBC between elevavtions and soil depths (0-10cm and 10-20cm).Moreover,clear seasonality in the ratio of MBC to MBN was observed.

Key words: alpine soil, microbial biomass carbon, soil labile carbon, altitudinal gradient, seasonal dynamic