中文摘要：

采用径流小区法研究天然降雨条件下18年尾叶桉（Eucalyptus urophylla）人工林地、16年马占相思（Acacia mangium）人工林地及采伐迹地2010年降雨集中期内的径流量,径流中各形态氮、磷浓度,氮、磷流失量及动态变化特征。结果表明：监测期内尾叶桉人工林累积径流量（211.28m3/hm2）与采伐迹地（204.05m3/hm2）无显著差异（p〉0.05）,但均显著高于马占相思林（83.76m3/hm2）（p〈0.05）;尾叶桉林、马占相思林和采伐迹地径流总氮平均浓度分别为4.01,2.69,2.97mg/L,总磷平均浓度分别为0.31,0.18,0.19mg/L,不同林地间差异均不显著（p〉0.05）,3种林地氮素径流流失均以铵态氮为主,磷素流失以颗粒态磷为主;尾叶桉林、马占相思林和采伐迹地的总氮累积流失量分别为620.33,196.14,486.15g/hm2,总磷累积流失量分别为40.66,13.64,33.45g/hm2,3种林地之间均存在极显著差异（p〈0.01）;氮、磷流失量均与径流量呈显著（p〈0.05）或极显著（p〈0.01）正相关关系。

英文摘要：

By using runoff plot method,the surface runoff yield,concentrations of nitrogen（N）and phosphorus（P）of different forms in runoff water,accumulative runoff losses of total N and P and their temporal change in 18-year-old Eucalyptus urophylla plantation,16-year-old Acacia mangium plantation and a clear-cutting land in south China under natural rainfall conditions during the rainy season in 2010 were analyzed.Results revealed that during the monitoring period,accumulative runoff yield of E.urophylla plantation land（211.28 m3/hm2）were not significantly different from that of clear-cutting land（204.05 m3/hm2）（p0.05）,but both were significantly higher than that of A.mangiumland（83.76m3/hm2）.The mean total N concentrations of E.urophyllaplantation,A.mangiumplantation and clear-cutting lands were 4.01,2.69,2.97mg/L,respectively,and the respective mean total P concentrations were 0.31,0.18,0.19 mg/L.Both total N and total P concentrations were no obvious difference among the three lands（p0.05）.Nitrogen and P losses via runoff occurred mainly in the form of ammonium and dissolved particulate P,respectively.Accumulative losses of total N in E.urophylla plantation,A.mangium plantation and clearcutting land were 620.33,196.14,486.15g/hm2,respectively,and those of total P were 40.66,13.64,33.45g/hm2,respectively,with both N and P losses being significantly different among the three lands（p 0.01）.Runoff yield exhibited significant positive correlation with total N and P losses.