植物群落的本质特征之一是群落中的植物和环境之间存在一定的相互关系。湿润的丘陵地区是由水侵蚀而形成的包含各种干扰频率的生境复合体，作为中尺度的地形单位，可以通过侵蚀前线划分为上部坡面和下部坡面两个小尺度的地形单位，而上部坡面可以进一步划分为顶坡、上部边坡、谷头凹地等微地形单元，下部坡面可以进一步划分为下部边坡、麓坡、泛滥性阶地及谷床等微地形单元。上部坡面发育的是气候顶极群落，沿顶坡向谷头凹地， 群落发生逐渐、连续的变化，下部坡面发育的为地形群落，其物种组成、结构以及其它生态特征与上部坡面具有显著的差异，而其微地形单元之间植被的变化不明显。干扰作用是不同地形植被分异的控制因子，也是地形植被维持和更新的关键因子。下部坡面以相对积极的土壤侵蚀、滑坡和崩塌等过程为特征，其植被更新依赖于频繁的地面干扰，而上部坡面长期稳定，其植被更新依赖于林窗动态。地形是影响植被格局的最重要的也是最基本的生境因子， 其引起的生境生态位分化为物种的共存提供了条件，导致了小尺度空间内高生物多样性的形成和维持。
The relationship between plants and environmental conditions is one of the most basic characteristics of plant communities. The humid hilly regions are a complex habitat that has various degrees of disturbance related to water erosion. At an intermediate_scale level, the region can be divided into an upper and lower hillslope area divided by an erosion front. At a more detailed_scale, the sections can be divided further into micro_scale geomorphological units. The upper hillslope area contains a crest slope, upper sideslope and head hollow etc. and the lower hillslope contains a lower sideslope, foot slope, flood terrace and river bed etc. The upper and lower hillslopes are two basic functional land area types for assessing species composition and forest structure. On the upper hillslope area, the vegetation changes gradually and continuously from the crest slope, to upper sideslope and head hollow. On the lower hillslope, however, the micro_landform units have little effect on vegetation structure as disturbance plays the most important role in regulating vegetation patterns. The lower hillslope area is characterized by active soil erosion, landslides and slope failures. Thus, the plant communities that develop on it are early successional communities, and their regeneration depends on active surface disturbance. However, the plant communities that develop on the upper hillslope areas are climate climax communities as it has been stable for a long time, and their regeneration can be explained based on the gap dynamic theories. Topography is the most basic and important habitat factor affecting vegetation patterns. Habitat niche differentiati on related to topographic variation supports the coexistences of species and results in high species diversity at small spatial scales.