Response of Polygonum viviparum Species and Community Level to Long-term Livestock Grazing in Alpine Shrub Meadow in Qinghai-Tibet Plateau

Grazing by domestic herbivores is generally recognized as a major ecological factor and an important evolutionary force in grasslands, Grazing has both extensive and profound effects on individual plants and communities, We investigated the response patterns of Polygonum viviparum species and the species diversity of an alpine shrub meadow in response to long-term livestock grazing by a field manipulative experiment controlling livestock numbers on the Qinghai-Tibet Plateau in China, Here, we hypothesize that within a range of grazing pressure, grazing can alter relative allocation to different plant parts without changing total biomass for some plant species if there is life history trade-offs between plant traits, The same type of communities exposed to different grazing pressures may only alter relative species＇ abundances or species composition and not vary species diversity because plant species differ in resistant capability to herbivory, The results show that plant height and biomass of different organs differed among grazing treatments but total biomass remained constant, Biomass allocation and absolute investments to both reproduction and growth decreased and to belowground storage increased with increased grazing pressure, indicating the increasing in storage function was attained at a cost of reducing reproduction of bulbils and represented an optimal allocation and an adaptive response of the species to long- term aboveground damage, Moreover, our results showed multiform response types for either species groups or single species along the gradient of grazing intensity, Heavy grazing caused a 13,2% increase in species richness, There was difference in species composition of about 18%-20% among grazing treatment, Shannon-Wiener （H′） diversity index and species evenness （E） index did not differ among grazing treatments, These results support our hypothesis,

The diversity of soil culturable fungi in the three alpine shrub grasslands of Eastern Qilian Mountains

To understand the diversity of culturable fungi in soil at alpine sites, Rhododendron fruticosa shrubland, Salix cupularis fruticosa shrubland, and Dasiphoru fruticosa shrubland of the Eastern Qilian Mountains were selected to investigate. Three methods, including tradi- tional culturing, rDNA internal transcribed spacer （ITS） sequence analysis, and economical efficiency analysis, were carried out to estimate the diversity of soil culturable fungi of these three alpine shmblands. A total of 35 strains of culturable fungi were cultured by dilution plate technique and were analyzed by rDNA ITS sequence. The diversity indices such as species abundance （S）, Shannon-Wiener index （H）, Simpson dominance index （D）, and Pielou evenness index （3） of Rhododendron fruticosa shrubland, Salix cupularis fruticosa shrubland, and Dasiphoru fruticosa shrubland were ranged between 16 and 17, 2.66-2.71, 0.92, 0.95~）.97 respectively. The results showed that the diversity of soil fungi were abundant in these three types of alpine shrub grasslands, while further study should be done to explore their potential value.