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乌江流域坡耕地是水土流失的主要来源，以单行稀疏地埂树为主的传统坡耕地农林复合植被类型，除能起到一定的固坡护埂作用外，对坡面径流影响甚微，不能有效控制水土流失。为此，提出了分带营造坡耕地水保防护林的方法，在坡面配置上引入临界坡长的概念，采用临界坡长作为配置防护林带的间距，根据林带间耕地的产流携沙量确定林带宽度。考虑到林带间距较密，遮荫胁地影响突出，因此以林带充分发挥防护功能，在不改进耕作方式的情况下，营建土地单位的粮食总产量不减为前提，确定林带高度的上限值，从而在山区混交农林的研究上第一次找到求算不同耕地类型（基岩特性、坡度、土层厚度等）营造防护林带的带距、带宽和带高上限值，并以此为依据进行合理树种选择和搭配的有效办法。
Slope cropland is the main source of soil and water loss in Wujiang River Basin. The agroforestry vegetation types of traditional sloping farmland dominated by sparsely poplar trees in single row have little effect on slope runoff, Effective control of soil erosion. Therefore, we proposed the concept of zoning to create water conservation shelterbelt of sloping farmland, introduced the concept of critical slope length on the slope configuration, adopted the critical slope length as the spacing of shelter belt, and determined the runoff carrying capacity of cultivated land Forest width. Taking into account the densely spaced forest belts and the prominent impact of shade and threatening, the forest belt should give full play to its protective functions. Under the condition of not improving cultivation methods, the total output of grain for the construction of land units should be reduced on the premise that the upper limit , And for the first time in the research on the mixed agriculture and forestry in the mountainous area, find the upper limit of the belt distance, the bandwidth and the height of belt for different types of cultivated land (bedrock characteristics, slope, soil thickness, etc.) Effective species selection and collocation of effective ways.