Spatial distribution in forest soil nutrients and its relationship with ecological factors on the up stream of Taihu lake basin

To examine the role of the forest in non-point source pollution control in the Taihu lake region, the soil profile nutrients including nitrate, hydrolyze nitrogen(HN), available phosphorus(AP), total nitrogen(TN), total phosphorus(TP) concentration of 26 forest sample plots along the Xitiaoxi River from upstream to downstream were measured through July to August 2009, the relationship between vegetation type and topographic factors and soil nutrients was analyzed. results show that: (1) All of five soil nutrients concentration decreased with increasing soil depth; (2) Soil nutrients of different soil depth is intermediate variability, the coefficient of variation of AP, TN, HN, TP were increased with the increasing of soil depth, and the coefficient of variation of nitrate was decreased with the increasing of soil depth. (3)Soil HN content under plots with an average tree height above 10m was significantly higher than plots with an average tree height less than 10m; (4) Soil AP, RN, TN, TP content was first decreased and then increased with the increasing of elevation. .In summary, the soil nutrients of different soil depth was found to be closely related to vegetation type, community age, structure, fertilization and topographic features in the upstream of Taihu lake basin.