围栏封育和自由放牧对克氏针茅草原植被空间异质性的影响

群落组成结构的异质性是群落动态的主要属性。本研究采用样线、样方调查方法,基于物种频度与幂函数法则,分析了内蒙古克氏针茅草原围栏封育和自由放牧条件下群落物种结构与空间异质性的变化。结果表明:在围栏外和围栏内不同利用方式下,物种均呈现集中分布;从水分生态型、生活型、生育型、种子传播型和植物科属等不同功能群类别来看,旱生植物和中旱生植物广泛分布,生活型以多年生草本植物为主,依靠重力传播种子的植物占有相对较大的比例,达到60%以上,禾本科、百合科、菊科和豆科等适牧植物具有相对优势;在围栏保护状态下,物种多样性增加,群落异质性降低,放牧退化草原开始向群落状况良好的草原类型演替。

Effects of exdosure and uncontrolled grazing on spatial heterogeneity of Stipa krylovii steppe vegetation

The heterogeneity of plant community species composition is the main attribute of plant community dynamics.By using line transect and quadrat methods,and based on species frequency and power law,this paper analyzed the variations of plant community species composition and spatial heterogeneity in an Inner Mongolian Stipa krylovii steppe under exclosure and uncontrolled grazing conditions.Inside and outside of the exclosure,the plant species all presented a centralized distribution.In terms of functional groups,xerophytes and mesoxerophytes were widely distributed inside and outside of the enclosure.Perennial herbaceous species dominated in life form.More than 60% of the species spread their seeds by gravity.Gramineae,Liliaceae,Compositae,and Leguminosae had a comparative advantage.Under exclosure,species diversity increased while community heterogeneity decreased,suggesting that the degraded grassland due to grazing was changing better.