放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制

Effects of grazing patterns on grasshopper community biodiversity and its mechanism on the alpine meadow

为明确不同放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制,本研究调查牛放牧、羊放牧、牛羊混合放牧和休牧4种模式下高山草地植物群落特征、蝗虫群落组成和数量,分析蝗虫群落生物多样性特征,利用冗余分析方法分析植物群落与蝗虫群落的相关性,采用结构方程模型分析放牧模式对蝗虫群落的影响路径。结果显示,与休牧相比,牛放牧、羊放牧、牛羊混合放牧模式显著影响高山草地植物群落高度、植物群落覆盖度和禾本科牧草高度,但对植物群落生物多样性影响不显著。4种放牧模式下共捕获蝗虫13种,不同放牧模式下,高山草地的生物指示种不同。与休牧模式相比,牛放牧、羊放牧、牛羊混合放牧模式显著影响高山草地Shannon-Wiener指数、Simpson优势度指数和Pielou均匀度指数;在牛放牧、羊放牧和牛羊混合放牧模式下,高山草地蝗虫群落Shannon-Wiener指数分别为0.36、0.35和0.29,高山草地蝗虫群落Simpson优势度指数分别为0.45、0.45和0.35,高山草地蝗虫群落Pielou均匀度指数分别为0.33、0.33和0.24。高山草地植物群落高度、覆盖度和禾本科牧草高度与红翅皱膝蝗Angaracris rhodopa、鼓翅皱膝蝗A.barabensis、青海痂蝗Bryodema miramae等呈负相关,与狭翅雏蝗Chorthippus dubius呈正相关。结构方程模型分析表明不同高山草地放牧模式主要通过改变植物群落高度间接影响蝗虫群落生物多样性。

To understand the effect of grazing patterns on grasshopper communities and its mechanism,the characteristics of plant community,composition and number of grasshopper community were investigated.The grasshopper community biodiversity was calculated;redundancy analysis was performed to analyze the relationships between plant and grasshopper communities during the periods of yak,sheep,yak-sheep grazing and rest grazing,and the structural equation models were constructed to reveal the pathway of grazing patterns influencing grasshopper community.The results showed that,compared with rest grazing,the yak,sheep,yak-sheep grazing patterns significantly changed the height,coverage of plant community and forage grass height but did not change the biodiversity.A total of 13 species of grasshoppers were caught during the study period.The biological indicator species of alpine meadow were different under different grazing patterns.Compared with rest from grazing,the yak,sheep and yak-sheep grazing patterns significantly affected the grasshopper community indices:Shannon-Wiener index 0.36,0.35 and 0.29,Simpson dominance 0.45,0.45 and 0.35,and Pielou evenness 0.33,0.33 and 0.24,respectively.The plant community height,coverage and forage grass height had negative correlations with Angaracris barabensis,A.rhodopa and Bryodema miramae,and had a positive correlation with Chorthippus dubius.The structural equation modeling showed that the indirect effect of plant community height on grasshopper community was the main way influencing the structure of grasshopper community by grazing patterns in alpine grasslands.