黄土丘陵区植物群落多样性及生物量随土壤水分梯度变化特征

了解土壤水分与物种多样性及生物量的关系对探究植物群落特征与分布具有重要意义。以陕北黄土丘陵区吴起、米脂、府谷、定边4个典型区域为研究对象,对比分析降水量影响下的土壤水分梯度对自然恢复植物群落多样性、生物量的影响,为黄土丘陵区植被恢复和生物多样性管理提供科学依据。结果表明:随降水量自东南向西北逐渐减少土壤水分呈降低趋势,吴起、米脂、府谷和定边平均土壤含水量分别为9.77%、9.40%、7.91%和6.40%;4个区域调查统计到植物24科56属71种,其中禾本科、菊科、豆科植物占多数且以草本植物为主;随着土壤含水量降低,4个典型区域植物群落物种组成具有较低的相似性,说明物种组成随土壤水分变化而更替;同时,群落生物量、Margalef指数、Shannon指数以及Pielou指数均表现出逐渐降低趋势,且群落生物量、Margalef指数、Shannon指数与浅层土壤含水量呈显著正相关。研究表明,土壤水分变化对群落物种组成、植物群落多样性及生物量有重要的影响,研究区植被恢复建设必须要考虑土壤水分承载力。

The variation of plant community diversity and biomass along a soil water gradient in loess hilly region

Understanding the relationship between soil moisture and species diversity and biomass has great significance for exploring plant community characteristics and distribution. We examined the effects of soil water gradient on the diversity and biomass of naturally restored plant communities in Wuqi,Mizhi,Fugu and Dingbian which are located in typical loess hilly region in Northern Shaanxi. The aim of this study was to provide scientific basis for vegetation restoration and biodiversity management in loess hilly area. The results showed that soil water content exhibited a decline trend with the decrease of precipitation from southeast to northwest. The average soil water contents in Wuqi,Mizhi,Fugu and Dingbian were 9.77%,9.40%,7.91% and 6.40%,respectively. A total of 71 species,belonging to 56 genera and 24 families were recorded in the study sites. Among all those species,species from Gramineae,Asteraceae and Leguminosae were dominated and herb species accounted for the large proportion. With the decreasing soil water content,plant community composition had low similarity among the four study sites,indicating that species composition changed with soil water content. Meanwhile,community biomass,Margalef index,Shannon index and Pielou index all showed a decreasing trend with decreasing soil water content.Additionally,community biomass,Margalef index and Shannon index had significant positive correlation with water content of shallow soil. Our results indicated that soil water had an important effect on plant community species composition,diversity,and biomass,and that soil water carrying capacity should be considered in vegetation restoration and construction in this area.