青海湖流域高原鼠兔扰动对不同地表类型土壤水分特征的影响

为了揭示高原鼠兔扰动对高寒草甸土壤水分变化的影响规律,在青海湖流域,利用动态监测和采样分析的方法,研究高原鼠兔扰动后不同地表类型(草地、新鼠丘、旧鼠丘和秃斑地)土壤水分的差异及其形成原因.结果表明:4种地表类型土壤表层含水量对不同降雨条件具有不同的响应过程,新鼠丘和旧鼠丘的响应比草地和秃斑地迅速;整个生长季4种地表类型土壤含水量垂直分布规律不同,但月变化规律较为一致,总体上草地土壤含水量高于其他地表类型,0 ～ 30 cm深度的差异最明显;造成不同地表类型土壤水分差异的土壤因素主要有土壤黏粒质量分数、土壤有机质和土壤密度,植被因素主要有植被盖度和地上生物量.高原鼠兔扰动初期可以加速水文循环,而后期水文循环则受到抑制.研究对进一步认识高原鼠兔的扰动影响高寒草甸的水源涵养能力具有重要作用,也可为青海湖流域生态系统的管理与保护提供参考.

Effects of plateau pika's disturbance on soil moisture characteristics of different land surface types in Qinghai Lake watershed

[Background] The plateau pika (Ochotona curzoniae) is a keystone species for maintaining the biodiversity on the Qinghai-Tibet Plateau,and its disturbance has an important influence on the function of alpine meadow ecosystem.To date,however,few studies have examined the soil moisture characteristics of different land surface types generated by the plateau pika's disturbance.[Methods] The study was carried out in the Qinghai Lake watershed,northeast of Qinghai-Tibet Plateau.There are four typical land surface types generated by the plateau pika's disturbance:grassland,new mound,old mound and bare land.We investigated the characteristics of soil moisture and its corresponding influence factors (including soil clay content,soil organic matter,soil bulk density,vegetation coverage,and aboveground biomass) among four land surface types,based on the continuous measurement and sampling analysis.Firstly,we analyzed the response of soil moisture to various rainfall events,and the vertical distribution of monthly soil moisture of different land surface types.Then,the redundancy analysis (RDA) was used to get the key factors leading to these differences.[Results] Plateau pika's disturbance often generated various surface types,resulted in the direct and indirect effects on the soil physicochemical properties,and then changed the soil moisture characteristics of alpine meadow ecosystem.The response of soil moisture at shallow layer to various rainfall events was different.The beginning time of new mound and old mound was shorter than that of grassland and bare land,and the changing extent of soil moisture response to various rainfall events had the following trend:new mound ＞ old mound ＞ grassland ＞ bare land.The vertical distribution of soil moisture varied obviously between four land surface types during the whole growing season.With the increase of soil depth,the soil moisture firstly decreased and then increased for grassland,firstly increased and then decreased for new mound,and continually decreased for old mound and bare land.Generally,the soil moisture of grassland was higher than other land surface types,and the difference of soil moisture at the depth of 0-30 cm was the most significant.The key factors resulting in the differences of soil moisture among different land surface types included soil clay content,soil organic matter,soil bulk density,vegetation coverage,and aboveground biomass.[Conclusions] The experimental results showed that the plateau pika's disturbance accelerated the hydrological process in the beginning,and slowed it later.These results are essential in explaining the effect of plateau pika's disturbance on water conservation capacity of alpine meadow,and could also be beneficial to the management and protection of the ecosystem in Qinghai Lake watershed.