黄土丘陵区不同坡向及坡位草本群落生物量及多样性研究

以黄土丘陵区纸坊沟流域内的大范家沟阴阳坡和拐沟阴坡坡面主要草本群落为研究对象,分析不同坡向及坡位的草本群落盖度、地上生物量及物种多样性关系。结果表明,阴坡草本群落的物种20多种,较阳坡高30%。阴阳坡面上草本群落生物量和盖度从坡下至坡上逐渐减小。在水分和养分条件好的地段均有灌木入侵。阳坡Margalef和Menhinick丰富度指数均随坡位升高而降低;而阴坡Mafgalef指数随坡位升高而降低,Menhinick指数却随坡位升高而增大;3个均匀度指数和多样性指数在阴阳坡均随坡位的升高而减小。不同坡位引起的植被盖度、Margalef丰富度指数和Alatalo均匀度指数存在显著差异（P〈0.05）。坡位与Margalef丰富度指数和Alatalo均匀度指数呈显著相关（P〈0.05）,与Shannon-wiener多样性指数呈极显著相关（P〈0.01）。描述或评价群落多样性、丰富度及均匀度时,应多选几个指标参数,避免单一指标带来的片面性。掌握草本群落自身喜阴阳特性、生境特征、植被组成及多样性特征,充分认识植被演替条件和演替规律,对指导该区植被和生态系统恢复与重建具有重要意义。

Biomass and species diversity of herbosa at different position and aspects of slope in the Hilly-gully Region of Loess Plateau

Based on the investigation of herbasa of different positions and aspects of slope in the Dafanjiagou and Guaigou of Zhifanggou watershed on the Loess Plateau,the indices of coverage,above-ground biomass and species diversity were analyzed.The results showed that the number of species reach to twenty in the shady slope,thirty percent more than that of sunny slope.The biomass and coverage of herbosa is decreasing from upper slope to the lower slope both on the sunny and shady slope.The shrubs appears in the batter condition with more water and nutrients.Margalef and Menhinick richness indices are decreasing with slope position raising in the sunny slope,while Mafgalef index in the shady slope has the same law,but Menhinick index in the shady slope is increasing with slope position raising.The three eveness indices and biodiversity indices are all decreasing with raising of slope position.There are significant difference among herbosa coverage,Margalef and Alatalo indices of different slope positions（P＜0.05）.Meanwhile,there are also significant positive correlation between slope position and Margalef index,Alatalo index（P＜0.05）,also extremely significant positive correlation between slope position and Shannon-wiener index（P＜0.01）.In order to avoid one sidedness causing by using signal index,it would be better to choose more biodiversity indices to describe or evaluate diversity,richness or evenness of herbosa in practice.Mastering the characters of herbosa,its habitats and recognizing succession condition and discipline are very important for guiding the ecosystem restoration.