藏东南巴宜区不同土地利用方式碳氮含量分布特征

Distribution Characteristics of Carbon and Nitrogen Content in Different Land Use Modes in Bayi District,Southeast Tibet

为了研究藏东南巴宜区不同土地利用方式碳氮垂直分布情况,在西藏农牧学院周边选择三种不同利用方式的土壤为研究对象,测定土壤有机碳、全氮等指标。结果表明:(1)土壤全氮含量总体随着土层的深入而降低,3种土地利用方式的土壤全氮平均含量(g/kg)表现为:草地(2.00±0.45)>森林(1.68±0.19)>农田(0.95±0.05),且草地和农田之间差异显著(F=4.61,P<0.05),其垂直空间变异性表现为:草地(68.00%)>森林(34.43%)>农田(16.00%);(2)土壤有机碳含量分布规律与全氮变化特征相似,土壤有机碳平均含量(g/kg)表现为:森林(60.90±3.98)>草地(54.28±11.68)>农田(31.97±1.02),且森林和农田之间差异显著(F=5.41,P<0.05);按垂直空间变异性由大到小的顺序为草地(65.99%)>森林(24.00%)>农田(10.00%);(3)3种土地利用方式下土壤有机碳密度均随土层深度的增加逐渐减小,就平均而言,森林土壤的有机碳密度最大,其次为草地和农田。

In order to study the vertical distribution of carbon and nitrogen in different land use modes in Bayi District,Southeast Tibet,three soils with different utilization modes were selected as the research object around Tibet Agriculture and Animal Husbandry University to measure soil organic carbon,total nitrogen and other indicators.The results showed that the soil total nitrogen content generally decreased with the depth of soil layer,and the average content of soil total nitrogen(g/kg)of the three land use modes was as follows:grassland(2.00±0.45)>forest(1.68±0.19)>farmland(0.95±0.05).There was significant difference between grassland and farmland(F=4.61,P<0.05),and the vertical spatial variability showed as follows:grassland(68.00%)>forest(34.43%)>farmland(16.00%).The distribution law of soil organic carbon content was similar to that of total nitrogen,and the average content of soil organic carbon(g/kg)was as follows:forest(60.90±3.98)>grassland(54.28±11.68)>farmland(31.97±1.02),but there was significant difference between forest and farmland(F=5.41,P<0.05),and the order of vertical spatial variability was grassland(65.99%)>forest(24.00%)>farmland(10.00%).Under the three land use modes,the soil organic carbon density decreased gradually with the increase of soil depth.On average,the organic carbon density of forest soil was the largest,followed by grassland and farmland.