Effects Of Plateau Pika Clipping On Niche And Interspecifc Association Of Plant Population In Alpine Meadows

Plateau pikas(Ochotona curzoniae)often clip the tall upright plants near active burrow entrances and their trails to detect and avoid natural enemies,which can change the ability of different plants in community to utilize the resource in the clipped area,modifying the relationship between any two plants in the original plant community.Previous studies that examine the effects of plateau pika clipping on plant communities have focused on the apparent characteristics of plant communities,but the mechanism of how changes of these apparent characteristics happen are still unclear.In this study,two sites were used parallely to determine the responses of plant population niche,interspecific association and interspecific correlation to plateau pika clipping,which can present the mutual confirmation,and provide basic information for revealing the internal mechanism of apparent characteristics changes in plant community induced by plateau pika clipping.This study selected the Gangcha County in Qinghai Lake Region and Luqu County in Gannan of Gansu province as survey sites.Following the methods from previous studies,this study designed abandoned burrow entrances as the control area and active burrow entrances were as the clipping area.The differences in ecological niche,interspecific association and interspecific correlation of plant populations between near active burrow entrances and near abandoned burrow entrances were used to clarify the response degree and response rate of plant population to clipping behavior by plateau pika,which is helpful to disclose the cooperative or competitive relationship among plant species within the community.These results can improve the research field of the effect of clipping of small rodent herbivores on grassland plant community,and can provide useful information for the scientific management of plateau pika.The main conclusions are as follows:1.Plateau pika clipping had important effects on the ecological attributes and ecological response rate of plant population by changing the niche width and overlap degree of plant population in plant community.In Gangcha County,plateau pika clipping increased the niche width of 57.7%plant species,decreased the niche width of 42.3% plant species,and changed the relative competitiveness capacity of 15.69% plant species pairs,and the ecological attributes of 7.7% plant species populations.At survey site in Luqu County,plateau pika clipping increased the niche width of 44.4% of plant species,decreased the niche width of 55.6% of plant species,changed the relative competitiveness capacity of species pairs by 16.24%,and the ecological attributes of plant species population by 14.8%.These results from two survey sites showed that plateau pika clipping altered the niche width of all plant populations,but only changed the relative competitiveness and ecological attributes of some plant populations.2.The clipping by plateau pikas enabled the overall interspecific association to transform from non-significant positive association to a significant negative association,decreased the proportion of positive association species pairs and increased the proportion of negative association species pairs.Data from survey sites in both Gangcha County of Qinghai Lake Region and Luqu County of Gannan showed that plateau pika clipping changed the overall association characteristics of plant communities in alpine meadows,indicating that plateau pikas clipping transformed overall interspecific association from non-significant positive association in abandoned entrances to a significant negative association in active entrance,which implied that plateau pika clipping would intensify species competition within the plant community.Plateau pika clipping changed the interspecific association characteristics of 46.46% and 45.30% paired species in Gangcha County and Luqu County,indicating that plateau pikas clipping decreased the number of paired species with positive interspecific associated,and decreased the number of paired species with negative interspecific associated,which implied that plateau pika clipping could not only change the interspecific association properties of plant species pairs,but also change the degree of association between species pairs.3.Plateau pika clipping increased the number of paired species with positive correlated species and decreased the number of paired species with negative correlated in the plant community.The results of Pearson analysis showed that the number of paired species with positive correlation of plant communities in Gangcha County and Luqu County increased from 38.77% and 43.02% in the abandoned entrance area to 42.46% and 45.30% in the active entrance area,respectively,and the number of paired species with negative correlation decreased from 61.23% and 56.98% in the abandoned entrance area to 57.54% and 54.70% in the active entrace area,respectively.However,the results of Spearman analysis showed that the number of paired species with positive correlation of plant communities in Gangcha County and Luqu County increased from 41.23% and 45.30% in the abandoned entrance area to 43.69% and 45.58% in the active entrance area,and the number of paired species with negative correlation decreased from 58.77% and 56.98% in the abandoned entrance area to 54.70% and 54.42% in the active entrance area.Although the results of the two statistical methods were different,the results showed that the clipping by plateau pika increased the number of paired species with positive correlation and decreased the number of paired species with negative correlation in the plant communities of Gangcha County and Luqu County.