A Study On The Relationship Between The Temporal Stability Of The Alpine Meadow Population And The Temporal Stability Of The Community

Biodiversity plays an important role in maintaining and improving the stability of ecosystem functions.In recent years,scholars both at home and abroad have done a lot of researches around the selection effects and complementary effects that maintain the temporal stability of community and the functions of ecosystem,they also explored the relationship of species diversity,the temporal stability of population and the temporal stability of community.However,there are still a lot of controversies about them.Theoretical research shows that the relationship between the temporal stability of population and the temporal stability of community is related to the variations of population caused by increasing species diversity,and it can determine the relevant correlation between the temporal stability of population and community.This change is also closely related to the mechanisms that determine the temporal stability of community.In our study,we choose the alpine meadow in the Qinghai-Tibet Plateau as the research object.Based on 11 years of species cover data,we explore the influence of disturbance of clipping and fertilization on the temporal stability of population and the temporal stability of community.We also explore the relationship among species diversity,the temporal stability of population and the temporal stability of community.We hope to verify the theoretical prediction of Tilman's about the relationship between the temporal stability of population and community.Our investigation include the following aspects:(1)the effects of clipping and fertilization disturbance on species diversity;(2)the effects of clipping and fertilization on the temporal stability of community;(3)the effects of clipping and fertilization on the temporal stability of population;(4)the relationship among species diversity,the temporal stability of population and the temporal stability of community under clipping and fertilization disturbance;(5)the relationship between the temporal stability of dominant species and the temporal stability of community;(6)the relative contributions of various factors to the temporal stability of community.The results of the study are as follows:(1)Clipping and fertilization have opposite effects on species diversity.Clipping increases species diversity while fertilization reduces species diversity,and fertilization has greater impact on species diversity than clipping.(2)Clipping can improve the temporal stability of community and fertilization can reduce it,fertilization has also greater impact on the temporal stability of community than clipping.Clipping improve the portfolio effect,asynchrony effect and the temporal stability of population by increasing species diversity,these effects can improve the temporal stability of community.Fertilization reduces species diversity,portfolio effects,the temporal stability of mean population and the temporal stability of dominant and subdominant species,therefore it reduces the temporal stability of community.(3)Clipping has no direct effect on the temporal stability of mean population,but it improves the temporal stability of mean population indirectly by increasing species richness.Fertilization can reduce the temporal stability of mean population directly,and it can also reduce the temporal stability of community indirectly by reducing species richness or increasing the summed variance of species coverage.(4)There is portfolio effect in community and the regression slope z>2,increasing species diversity improves the temporal stability of population and the temporal stability of community,it confirms Tilman's theoretical predictions.There is positive correlation among species diversity,the temporal stability of population and the temporal stability of community.(5)Clipping had no significant effect on the temporal stability of dominant species,subdominant species and the combination of dominant species and subdominant species,while fertilization reduced the temporal stability of the three significantly.Besides,we found that the dominance effect did not become the dominant effect of maintaining the temporal stability of community under the disturbance of fertilization.The population factors that maintained the linear relationship between the temporal stability of mean population and the temporal stability of community were mainly subdominant species rather than dominant species.It shows that subdominant species can also play an important role in maintaining the temporal stability of community.(6)Path analysis shows that the temporal stability of mean population,Shannon-Wiener index and species richness are the three most important factors that determine the temporal stability of community,all of them are positive related to the temporal stability of community.Besides,increasing species diversity reduces the summed variance of species coverage,as well as the stability effect of dominant species driven by clipping directly can also improve the temporal stability of community.Asynchrony effect has weak influence on the temporal stability of community.In summary,when confronting the disturbance of clipping and fertilization,the temporal stability of community of alpine meadow is simultaneously regulated by the species diversity effect and dominance effect.It depends on the temporal stability of mean population,dominance effects,and portfolio effects directly.The temporal stability of mean population is the important factor among them.Increasing species diversity can increase the temporal stability of population and the temporal stability of community,it confirms Tilman's theoretical predictions that the positive correlation between the temporal stability of population and the temporal stability of community.