高原鼠兔干扰对川西北高寒草甸植物群落及土壤物理性状的影响

Effects of plateau pika disturbance on plant community and soil physical property of alpine meadow in northwest Sichuan

高原鼠兔(Ochotona curzoniae)是高寒草甸关键物种,在草地生态系统物质循环和能量转化中扮演着重要角色。采用样方法研究了高原鼠兔干扰对川西北高寒草甸植物群落特征及土壤理化性状的影响。结果表明:1)高原鼠兔干扰显著降低了高寒草甸植被盖度、高度、物种丰富度指数、均匀度指数、土壤含水量和紧实度(P<0.05),而显著增加了多样性指数、表层土壤容重(P<0.05);2)随干扰强度增加,植被盖度、高度和土壤紧实度呈显著下降趋势,而丰富度指数、多样性指数、均匀度指数和表层土壤的含水量均呈先上升后下降的趋势,在高原鼠兔有效洞口密度为375~735个/hm;时达到最高;3)高原鼠兔干扰显著降低了禾本科和豆科功能群多样性指数和重要值,而显著增加了杂类草功能群多样性指数和重要值(P<0.05),不同干扰强度下,各植被功能群多样性指数变化明显,其中,豆科功能群多样性指数呈下降趋势,而杂类草功能群多样性呈先上升后下降趋势。综上所述,高原鼠兔的干扰显著改变了川西北高原高寒草甸群落特征和土壤物理性状,适度的高原鼠兔干扰不仅增加了高寒草甸物种多样性,还改善了土壤条件,而高强度的鼠兔干扰降低了高寒草甸物种多样性和土壤含水量。

Plateau pika(Ochotona curzoniae) is a key species in alpine meadow, which plays an important role in material cycle and energy transformation of grassland ecosystem.A field survey was carried out to determine the effects of plateau pika disturbance on plant community characteristics and soil physical and chemical properties of alpine meadow in northwest Sichuan.The survey gave the following results:(1) Plateau pika disturbance significantly reduced the vegetation coverage, vegetation height, species richness index, evenness index, soil water content and compactness of alpine meadow(P<0.05),but significantly increased Shannon index and surface soil bulk density(P<0.05).(2) With the increase of disturbance intensity, the vegetation coverage, vegetation height and soil compactness of alpine meadow decreased significantly, whereas, the species richness index, diversity index, evenness index and surface soil water content all increased first and then decreased, and reached the highest value when the number density of effective holes of pika ranged from 375 to 735 per ha.(3) From the analysis of different functional groups of vegetation, it was found that the disturbance of plateau pika significantly reduced the diversity index and important value of gramineous and leguminous functional groups, but the diversity index and importance value of the functional group of weeds were significantly increased(P<0.05).Further more, the diversity index of each vegetation functional group changed obviously under different disturbance intensity.The diversity index of Leguminosae functional groups showed a downward trend, while the diversity index of weed functional groups showed an obvious initially increased and then later decreased trend with increase of the plateau pika disturbance intensity.In conclusion, the disturbance of plateau pika significantly changed the community characteristics and soil physical properties of alpine meadow in northwest Sichuan Plateau.Moderate disturbance of plateau pika could not only increase the species diversity of alpine meadow, but also improved the soil conditions, while high intensity disturbance reduced the species diversity and soil water content of alpine meadow.