三江源草地植被群落与土壤性质对不同鼠兔密度的响应

Response of vegetation community and soil properties of grassland to different density gradients of Ochotona curzoniae in the Sanjiangyuan Region

为了探究高原鼠兔(Ochotona curzoniae)对高寒草地的影响,2016年在三江源高寒草原选取4个不同高原鼠兔密度梯度的采样点取样,分别对植被群落特征、地上地下生物量、土壤理化性质与高原鼠兔密度梯度进行相关分析。结果表明,1)植被群落的物种丰富度整体上随鼠兔密度的增加呈现显著下降的趋势,但适量的高原鼠兔能够改变草甸植物群落的组成。2)地上生物量和地下生物量都随着高原鼠兔密度的增加而减少,但其根茎比整体随高原鼠兔种群密度梯度呈逐渐升高的趋势。3)不同土壤属性及其在不同土壤深度上对鼠兔种群密度梯度的响应差异显著,在0–20 cm的土壤中,多数土壤属性值随鼠兔种群密度梯度的增加呈现波动状递减趋势;无鼠兔采样点与高密度和低密度鼠兔采样点的土壤属性整体上差异显著,而与中密度鼠兔采样点的土壤属性值趋于近似。4)通过对所有采集的土壤性质指标与根茎比做热度图分析,发现土壤因子是影响植物根茎比变化的主要驱动力。结果表明,适度的高原鼠兔密度能够改变草原的植物群落结构,改善土壤营养,为草原生态系统的可持续发展做出一定贡献。

In order to explore the impact of rodents on alpine grassland ecosystems,we investigated the effect of different densities of plateau pika(Ochotona curzoniae)in the Sanjiangyuan(Source of the Three Rivers)Region in 2016 on different vegetation characteristics(aboveground biomass,underground biomass,species richness)and soil properties.The testing results indicate that the vegetation species richness decreased as pika density increased,and the plant community composition of meadow could be changed by an appropriate density of pika.In addition,as pika density increased,aboveground biomass and underground biomass decreased,but the root:shoot ratio increased.And there were significant differences for soil properties at different soil depths.Most soil properties showed a fluctuating downward trend at the soil depth of 0–20 cm as pika density increased.The soil properties of the areas without pika were significantly different to the areas with high and low densities of pika.Besides,according to the correlation analysis,it is concluded that soil factors are the main drivers of the changes in root:shoot ratio.The findings highlighted that certain levels of pika populations can change the plant community structure and improve soil nutrients,and consequently contribute to the sustainable development of the grassland ecosystem.