【摘要】 选取半干旱黄土丘陵沟壑区相似气候、土壤和立地条件下的4种密度白榆人工林为研究对象,通过调查林下物种组成和结构,比较不同密度人工林下的物种组成、结构特征及其差异,评价人工林林下植被的发育状况.结果表明:白榆林下共有维管束植物43种,分属18科35属;群落乔木层结构比较简单,灌木层优势种主要以建群种的幼苗和达乌里胡枝子为主,草本层物种较多,优势种为菊科、禾本科;当林分密度为1 667株/hm2时,乔木、灌木及草本层的物种丰富度、多样性、均匀度指数均较高.更多还原

【Abstract】 Choosing Ulmus pumila plantations of four kinds of densities planted in similar climate,soil and site conditions as study targets,the species and composition of understory were investigated to evaluate the development status of understory vegetation.The results showed that there were 43 species in understory of Ulmus pumila plantations,belonging to 35 genera and 18 families.The structure of tree layer was simple,the dominant species in shrub layer were seedlings of constructive species and Lespedeza davurica,the species in herbaceous layer was abundant with Compositae and Gramineae as the dominant families.Under the planting density of 1667 trees/hm2,the richness,diversity and evenness index of tree layer,shrub layer and herbaceous layer were all high.更多还原