不同放牧梯度上草原群落植物功能群的结构组成及其变化

以蒙古高原东部克鲁伦河流域的放牧退化草原为研究对象,依照植物水分生态型、生活型进行植物功能群划分,在此基础上,比较了不同放牧退化阶段植物功能群的结构组成、地上生物量和物种多样性的变化。结果显示:植物生活型功能群中,多年生杂类草在轻牧、中牧梯度上都占有明显优势,而一、二年生植物在重牧区占有优势;从生物量分布来看,多年生禾草在轻牧阶段占有绝对优势。植物水分生态型功能群中,旱生植物在轻牧、中牧和重牧状态下均占有明显优势;旱生植物在轻牧阶段生物量最大。从物种多样性指数的变化来看,多年生杂类草和多年生草本功能群多样性指数随放牧梯度的增加呈现减小趋势,一、二年生草本与灌木、半灌木以及中生植物功能群多样性,随放牧强度的加大而呈现递增规律。在群落水平上,轻牧下草原群落的物种丰富度最高,重度放牧区均匀度最高,中牧条件下Shannon-Weaver多样性指数最大。

Study on Structure Composition and Changes of Plant Functional Groups in Different Grazing Gradients

In this paper, we aggregate the plant species into two functional groups based on the moisture ecotype and life form, and compare the structure composition, the above ground bio-mass distribution and the diversity based on the division of plant functional groups in the regres-sive succession of Hulunber Stipa krylovii grassland, Inner Mongolia. The results showe that pe-rennial forbs have a significant advantage in light and moderate grazing areas, but annual or bi-ennial herb have an obvious advantage in heavy grazing areas in life form functional groups. Pe-rennial grasses have the absolute superiority in light grazing areas from the distribution of bio-mass perspective. Xerophyte has the absolute superiority in all of the light, moderate and heavy＆amp;nbsp;grazing areas in moisture ecological functional groups. The distribution of xerophyte is biggest under light grazing areas from the distribution of biomass perspective. In the species diversity in-dex（ H＆#39;） of the variation, the diversity index of perennial herbs and perennial forbs is decreased with the grazing levels increasing, and the diversity index of annual and biennial herbs and shrubs, subshrubs and mesophytes are increased with grazing gradients and showed an increasing regularity. In addition, species richness is highest in moderate grazing areas and the evenness is highest in heavy grazing area, but the Shannon-Weaver index was highest in moderate grazing area at community level.