中文摘要：

空间的土壤和在分水岭规模的时间的可变性的 Quantification 在生态的建模，精确农业，和自然资源管理是重要的。在在在在在西南的中国的长江的上面的活动范围的紫色土壤的多山的区域的一个小分水岭( 12.10 km2 )的不同陆地使用下面的土壤氮的时间空间的变化被使用常规统计调查， geostatistics ，并且一个地理信息系统以便为陆地管理和环境问题的控制提供信息。从在分水岭以内的 276 个地点的 552 件土壤样品(0 ～ 15 厘米) 的一个总数在 2011 的 4 月和 8 月被收集，并且为土壤总数氮(STN ) 和硝酸盐氮(NO3-N ) 分析了。我们在 4 月(旱季) 和 8 月(雨季) 在不同陆地使用以及时间的变化下面比较了 STN 和 NO3-N 的空间变化。结果证明 STN 内容被陆地使用类型深深地影响；中部的 STN 价值从 0.94 ～ 1.27 g

英文摘要：

Quantification of soil spatial and temporal variability at watershed scale is important in ecological modeling, precision agriculture, and natural resources management. The spatio-temporal variations of soil nitrogen under different land uses in a small watershed （12.10 km^2） in the hilly area of purple soil at the upper reaches of the Yangtze River in southwestern China were investigated by using conventional statistics, geostatistics, and a geographical information system in order to provide information for land management and control of environmental issues. A total of 552 soil samples （o to 15 cm） from 276 sites within the watershed were collected in April and August of 2o11, and analyzed for soil total nitrogen （STN） and nitrate nitrogen （NO3-N）. We compared spatial variations of STN and NO3-N under different land uses as well as the temporal variations in April （dry season） and August （rainy season）. Results showed that STN contents were deeply affected by land-use types; median STN values ranged from 0.94to 1.27g.kg-I, and STN contents decreased in the following order： paddy field 〉 foresfland 〉 sloping cropland. No significant difference was found for STN contents between April and August under the same land use. However, NO3- N contents were 23.26, 10.58, and 26.19 mg·kg^-1 in April, and 1.34, 8.51, and 3.00 mg·kg^-1 in August for the paddy field, sloping cropland and forestland, respectively. Nugget ratios for STN indicatedmoderate spatial dependence in the paddy field and sloping cropland, and a strong spatial dependence in forestland. The processes of nitrogen movement, transformation, absorption of plant were deeply influenced by land use types; as a result, great changes of soil nitrogen levels at spatial and temporal scales were demonstrated in the studied watershed.