放牧模式对祁连山东缘高寒草甸植被特征的影响

Effects of different grazing patterns to vegetationcharacteristics in an alpine meadow on theeastern edge of Qilian Mountains

摘要:

为明晰不同放牧模式对高寒草甸植被特征的影响,以祁连山东缘全年连续放牧(CG)、冷季重度放牧(HG)、冷季轻度放牧(LG)、全年划区轮牧(RG)和全年禁牧(NG)5种不同模式放牧草地为研究对象,系统研究植物群落组成和结构的变化。结果表明:植物群落的盖度、密度、地上生物量、地下生物量、Shannon-Wiener多样性指数、Pielou均匀度指数、丰富度指数和辛普森指数均在RG样地最高,而在CG样地最低。此外,NG样地禾本科植物密度显著提高,莎草科、豆科、杂类草植物密度、群落总密度、植物群落物种数和多样性降低,和RG样地相比,NG样地总物种数减少了20种。因此,为期5年禁牧致使高寒草甸植物群落结构单一化,不利于植物多样性的维持。从提高生产力和植物多样性的角度来看,全年划区轮牧是祁连山东缘高寒草甸生态系统的最佳放牧模式。

Abstract:

Grazing has significant effects on vegetation characteristics of grassland,but the effects of different grazing patterns on the community composition and structure of grassland remain unclear.Therefore,we investigated the height,density,coverage,above- and below-ground biomass,litter biomass and biodiversity in an alpine meadow under five different grazing patterns (continuous grazing (CG),heavy grazing during the dormant seasons (HG),lightly grazing during the dormant seasons (LG),rotational grazing (RG),and non-grazing (NG)) in the Qilian Mountains.The results showed that the all HG,LG,RG,and NG treatments significantly increased the vegetation coverage,density,above- and below-ground biomass,shannon-wiener diversity index,Pielou evenness index,richness index,and Simpson index than the CG treatment.And the highest values were found under the RG treatment.The NG treatment significantly increased the density of Gramineae plants,while significantly decreased the density of Cyperaceae,Leguminosae,forbs,total density,the total species,and biodiversity.There was 20 species plant lost from the community at the NG site,when compared to RG site.Five years of grazing exclusion in the alpine meadow reduced plant biodiversity and density,with the vegetation being dominated by only a few species with strong colonization abilities.Given the high productivity and biodiversity,the rotational grazing would be the best grazing strategy for the alpine meadow in the Qilian Mountains.