中文摘要：

本文采用通用水土流失方程USLE得到牡丹江市退耕还林前后水土流失量,并借助GIS空间分析得到退耕还林前后各侵蚀等级的转移矩阵、地形要素的分布指数以及各用地类型的侵蚀强度指数,全面、科学地揭示了退耕还林前后水土流失的演变规律及其空间分布特征。结果表明：（1）退耕后剧烈侵蚀面积大量减少,由退耕前的3161.52km2减少到退耕后的672.38km2;极强度侵蚀面积大量增加,由退耕前的691.32km2增加到退耕后的2822.72km2。（2）退耕后,中山地带因植被覆盖增强其水土流失大大减弱;山前平原因耕地资源减少,人为加大土地开发利用强度而导致更容易发生水土流失。（3）〉15°坡度是退耕还林的主要发生范围,因林龄较低,其水土保持能力较弱,在强降雨等条件下更容易发生极强度和剧烈侵蚀。（4）退耕后,水田、草地和未利用土地土壤侵蚀强度指数增加,旱田、林地和建设用地土壤侵蚀强度指数减少。总体来讲,退耕还林有效遏制了研究区严重的水土流失状况,但退耕后轻度、中度和强度侵蚀还不稳定,容易向负向生态环境方向演化,且山前平原地带以及〉15°的退耕幼龄林区更易发生水土流失,因此水土保持工作依然不容松懈。

英文摘要：

Using the USLE （Universal Soil Loss Equation）, this study firstly got the soil loss quantity before and afterthe returning farmland to forest project（RFFP）,and then it obtained the soil erosion transfer matrix,distribution index of DEM and soil erosion intensity index in land use type.It revealed the develop mechanism of soil erosion and its spatial distribution.The results showed that：（1） the severe erosion area decreases sharply from 3161.52 km2 to 672.38 km2 after the RFFP; the very intense erosion area increases obviously from 691.32 km2 to 2822.72 km2.（2） The erosion weakens greatly in the middle mountain because the vegetation coverage there improves; on the contrary, soil erosion more easily occur in the plain area because people strengthen the farmland exploitation in the case of farmland decreasing.（3） The RFFP mainly takes place in 15°extent, and the forest age is so small that its soil and waterconservation ability is quite limited.Very intense erosion and severe erosion will occurmore frequently if there is heavy rainfall.（4） The soil erosion intensity of paddy field, grass andunusedlandincrease;contrarily, the soil erosionintensity of dry land, forestandbuildings decrease.Generally speaking, the RFFP relieves the severe soil erosion and improve the environment obviously, but the soil and water conservation should not be weakened because the slight erosion, middle erosion and intense erosion converse to worse more easily and in the plaint and young forest that distributed in 15°, the soil erosion could occur more frequently.