中文摘要：

以中国科学院海伦农田生态系统国家野外科学观测研究站的长期定位试验为平台,研究不同植被覆盖下土壤微生物量碳在作物生长季节的动态变化及其与土壤有机碳的相关性。结果表明,微生物量碳的变化趋势呈单峰型曲线,7月19日达到峰值,9月3日降到最低。不同植被覆盖下,土壤微生物量碳的平均含量以草地最高,作物覆盖居中,而裸地最低,三种农作物大豆、玉米和小麦在生长旺盛期达到最大值,分别为452.26 mg kg-1,371.05 mg kg-1,484.98 mg kg-1。不同植被覆盖下,不同土层有机碳含量的变化趋势为：0~10 cm〉10~20 cm,其中0~10 cm土壤有机碳和微生物量碳的相关性显著（P〈0.05）。微生物熵的变化趋势大致为：草地〉小麦〉玉米〉大豆〉裸地,说明长期自然恢复有利于土壤有机碳向微生物量碳的转化,有利于改善土壤质量。

英文摘要：

The effect of long-term black soil on the dynamics of microbial biomass carbon（MBC） of National Observation Station of Hailun Agroecosystem under different vegetations cover,and the correlations between MBC and organic carbon was studied.The results showed that with the variation of seasons,MBC changed as a single-peak curve,the peak appeared on the 19th July,and the minimum was on the 3th September.The content of MBC was highest in grassland,and the lowest was in bareland.The maximum of soybean,maize and wheat appeared in vigorous growth period and were 452.26 mg kg-1,371.05 mg kg-1 and 484.98 mg kg-1 respectively.Under different vegetation types,the trend of soil organic carbon（SOC）in different soil layers was： 0 ~ 10 cm 10 ~ 20 cm,and SOC in 0 ~ 10 cm had the maximum correlation with microbial biomass carbon.The variation trend of microbial quotient was： grassland wheat maize soybean bare land,which illustrated that long-term natural restoration was advantageous to the transformation of soil organic matter to microbial organic carbon.