中文摘要：

选择不同种植林龄和代次的杨树人工试验林地,2009年2至12月分层采集土壤样品分析了土壤微生物量氮（SMBN）的年动态变化规律和剖面分布特征。结果表明：所有试验林地SMBN的年动态变化规律相似,2月份SMBN含量最低,各试验林地SMBN的平均含量为48.36 mg/kg（0～10 cm）、38.74 mg/kg（10～20 cm）和22.64 mg/kg（20～40 cm）,10月份含量最高,平均为23.32 mg/kg（0～10 cm）、17.91 mg/kg（10～20 cm）和8.18 mg/kg（20～40 cm）。随着杨树种植林龄和代次的增加,SMBN的含量呈下降趋势。结果还显示,在动态采样期内,随着土层的加深SMBN含量降低,CK、F1、F2、S1及S2表土层（0～10 cm）SMBN的含量平均比10～20 cm和20～40 cm土层的分别高出11.50 mg/kg和24.83 mg/kg（CK）,13.40 mg/kg和25.30 mg/kg（F1）,9.34 mg/kg和19.53 mg/kg（F2）,7.17 mg/kg和19.00 mg/kg（S1）,5.65 mg/kg和14.48 mg/kg（S2）。相关分析显示,SMBN含量与土壤有机质和全氮呈显著相关关系（相关系数分别为0.665 4和0.829 6）。

英文摘要：

Different stand ages and rotations polar plantation sites were selected for investigating the dynamics and the distribution characteristics of soil microbial biomass nitrogen（SMBN） from February 2009 to December 2009.The results showed that SMBN annual change dynamics of all experimental sites was similar.The content of SMBN at February were the lowest and the average contents of all sites at different soil profiles were 48.36 mg/kg（0-10 cm）,38.74 mg/kg（10-20 cm） and 22.64 mg/kg（20-40 cm）,while the content of SMBN at October were the highest and the average contents of all sites at different soil profiles were 23.32 mg/kg（0-10 cm）,17.91 mg/kg（10-20 cm） and 8.18 mg/kg（20-40 cm）,respectively.With stand age and rotation of poplar plantation increase,SMBN content decreased.The results also displayed that SMBN content decreased with soil profile depth increase,SMBN average content at 0-10 cm was 11.50mg/kg and 24.83 mg/kg higher than that at 10-20 cm and 20-40 cm for CK,13.40 mg/kg and 25.30 mg/kg for F1,9.34 mg/kg and 19.53 mg/kg for F2,7.17 mg/kg and 19.00 mg/kg for S1,5.65 mg/kg and 14.48 mg/kg for S2,respectively.The correlation analysis indicated that there existed significant correlations between SMBN and soil total nitrogen and organic matter（correlation coefficient were respectively 0.665 4 and 0.829 6）.