绵羊放牧绢蒿荒漠草地植物群落多样性及其环境解释

对天山北坡放牧条件下的绢蒿草地进行野外调查,以探讨植物群落物种组成、多样性特征及其与环境因子之间的关系。结果表明:1)绵羊放牧过程中形成了明显的放牧强度梯度,草地利用率适中。通过除趋势对应分析 (DCA)将放牧区内的植物群落划分为8个类型,各类型植物群落的物种多样性有显著差异,且群落间存在异质性;2)采用除趋势对应典范分析法(DCCA)中的前项选择,对所获取的9个环境因子进行筛选,最终土壤有机质含量、粪便量、放牧强度、凋落物生物量、海拔、坡向等6个环境因子成为决定物种分布和群落结构组成的主导因素。DCCA排序结果反映出了实际的生态意义,有机质、放牧强度、粪便量在第一排序轴有明显的梯度变化,而坡向和凋落物则在第2轴上呈现出明显梯度变化,物种和群落也沿着上述环境要素的梯度变化而依次分布,很好地解释了放牧条件下绢蒿荒漠草地物种、群落与环境条件之间的关系。

Plant community diversity in grazed Seriphidium semidesert grassland and its relationships with environmental factors

This study investigated plant community species composition and biodiversity in grazed Seriphidium semidesert grassland, to explore the relationship between community structure and environmental factors. The results showed that: 1) Grazed grassland had an obvious grazing gradient by sheep, and the utilization of grassland was reasonable. A detrended correspondence analysis revealed eight plant communities in the grazed area. There were significant differences in species diversity indexes among plant communities, and there was heterogeneity among communities; 2) Six environmental variables (soil organic matter content, amount of feces, grazing intensity, litter biomass, altitude, and slope direction) were chosen by forward selection. The first axis of a detrended canonical correspondence analysis showed gradients of organic matter content, amount of feces, and grazing intensity, while the second axis showed gradients of litter biomass, altitude, and slope direction gradient among communities. The plant species and communities were distributed along gradients of environmental factors. Our results show that quantitative ecological methods provide more detailed information about ecological relationships between vegetation and the environment for grazed Seriphidium semidesert grassland.