黄土丘陵沟壑区封禁流域立地因子对植物群落特征的影响（摘要）

目的]研究黄士丘陵沟壑区封禁流域立地因子对植物群落特征的影响。方法]通过对陕西吴起县内封禁流域进行植被调查,研究了不同立地类型内植被群落特征和物种多样性的差异。结果]调查区域内植被群落以旱生草本植物为主,物种组成相对单一,结构简单。地带性植被类型为铁杆蒿（Artemisia sacrorum）＋茭蒿（Ar-temisiagiraldii）群落;植物多样性在不同地貌部位表现为梁顶〉沟底〉梁坡〉沟坡,在不同坡向表现为：半阴坡〉阴坡〉半阳坡〉阳坡的顺序;阳坡多样性指数随坡度的增加表现为＂S＂形变化趋势,37°左右达到最大值。结论]为黄土丘陵沟壑区的植物恢复提供了理论依据。

Effect of Site Factor on Plant Community Characteristic in Closed Watershed in Loess Hilly and Gully Region

Objective] The aim was to study the effect of site factor on plant community characteristic in closed watershed in loess hilly and gully region.Method] Based on the investigation of vegetation in the closed watershed of Wuqi County in Shaanxi Province,the difference of plant community characteristic and species diversity under various site types was researched in our paper.Result] In the investigation area,xerophytic herb was the main community,with sole species composition and simple community structure.Zonal vegetations were Artemisia sacrorum and Artemisia giraldii community;for plant diversity,the order of diversity index was ridge top>gully bottom>ridge slope>gully slope in various landform positions and semi-shady slope>shady slope>semi-sunny slope>sunny slope in various slope aspects;with the increase of gradient,the diversity index of sunny slope changed with "S" type,and it reached maximum value at 37°.Conclusion] Our study could provide theoretical foundation for vegetative restoration in loess hilly and gully region.