The Law Of Leaf Economic Spectrum Of Alpine Meadow Plants And Its Relationship With Population Time Stability

The research on leaf economic spectrum(LES)has been carried out for more than ten years,and the theory of leaf economic spectrum has been better developed and perfected.However,there are still many disputes about the study of leaf economic spectrum at present.For example,under the influence of long-term disturbance factors,whether or not the plant leaf economic spectrum and the traits of leaf economic spectrum will change adaptively,and what kind of adaptability changes will occur,there are not only few related studies,but also different conclusions.Furthermore,in the context of global climate change and human activities,the rapid loss of biodiversity has greatly affected the functional stability of ecosystems.Therefore,in recent years,the research on the impacts of biodiversity loss on the temporal stability of community and population has become a hot topic.The intrinsic driving force and mechanism of population temporal stability change have also been concerned.After the theory of leaf economic spectrum was put forward,some scholars proposed that the trade-off theory of leaf economic spectrum could be incorporated into the evaluation of the dynamic changes of population temporal stability.Plant functional traits related to leaf economic spectrum traits could provide a powerful framework to predict the changes" of population temporal stability.This is very important for understanding the regulation process of population temporal stability and inferring the models of species coexistence and ecosystem stability.However,few studies have been conducted.Based on the 12-year-long field experiment of clipping and fertilization control on alpine meadow in Qinghai-Tibet Plateau,this study explored and analyzed the changes of plant leaf economic spectrum traits and leaf economic trade-off strategy under long-term clipping and fertilization conditions,verified the wide applicability of leaf economic spectrum theory,and further analyzed the relationship between leaf economic spectrum trade-off theory and population temporal stability dynamics.In order to further understand the regulation process of population temporal stability under disturbance environment and further expand the scope of application of leaf economic spectrum theory.Specific research contents are as follows:(I)What impacts will long-term clipping and fertilization and their interaction have on leaf economic spectrum traits?(2)Will long-term clipping and fertilization lead to the convergent or divergent variation of plant leaf traits?(3)What is the impact of long-term clipping and fertilization on the leaf economic spectrum of plants,i.e.the trade-off strategy of plants?(4)Study on the relationship between the traits of leaf economic spectrum and population temporal stability.The main results are as follows:(1)Clipping and fertilization had different effects on leaf economic spectrum traits,but there was no significant interaction between them.Overall,clipping had no significant effect on leaf dry matter content(LDMC)and specific leaf area(SLA)of most plants,but the results of multiple comparisons showed that LDMC decreased and SLA increased significantly with increasing clipping intensity.Clipping resulted in a significant increase in leaf nitrogen content(Nmass)and leaf phosphorus content(Pmass).Fertilization significantly reduced LDMC and increased SLA,Nmass and Pmass.(2)Long-term clipping treatment did not induce the convergent or divergent response of plant leaf economic spectrum traits,while fertilization did induce the convergent response of them.There was no significant interaction between clipping and fertilization for trait convergence or variation.(3)The law of leaf economic spectrum also exists in alpine meadow affected by clipping and fertilization for a long time.Clipping did not cause significant changes in the trade-off strategy of leaf economic spectrum and leaf economic spectrum.Fertilization has relieved the restriction of soil nitrogen and phosphorus on plant growth in alpine meadow,however,resulting in the transfer of "fast-investment" income-based strategy with low LDMC,small SLA and low Nmass and Pmass content,resulting in significant changes in leaf economic spectrum.(4)There is indeed a correlation between the trade-off strategy of plant leaf economic spectrum and population temporal stability.Generally,species with low LDMC,large SLA,high Nmass and Pmass content had low temporal stability,while that with high LDMC,small SLA,low Nmass and Pmass content had high temporal stability.Clipping had no significant effect on the relational scheme.Fertilizer application would transfer the trade-off strategy to the "fast-investment" income end,resulting in a decrease in population temporal stability.(5)The trade-off between the leaf economic spectrum traits of plants can effectively predict the change of population temporal stability.However,LDMC is not always the best predictor,that is,single leaf economic spectrum traits can not accurately and effectively predict the change of population temporal stability.In order to accurately predict the change of population temporal stability,we need to consider the trade-off strategy of plant leaf economic spectrum comprehensively,that is to say,we need to analyze the change of each leaf economic spectrum trait.In conclusion,this study confirms the wide applicability of the theory of leaf economic spectrum.Long-term clipping does not have a significant impact on the traits of leaf economic spectrum and the strategy of trade-off of leaf economic spectrum.Long-term fertilization treatment will transfer the plant to the "fast-investment" strategy of LDMC reduction,SLA increase,Nmss and Pmass increase,and reduce the temporal stability of the population.Moreover,this study also proves that the trade-off theory of leaf economic spectrum is closely related to the change of population temporal stability.In addition,this study also identified that fertilization was the main driver for the trade-off of LES traits and the relationship between LES and population temporal stability in alpine meadow.The above results provide an important supplement to reveal the adaptation strategy of plants,population temporal stability and the mechanism of species loss under the background of global nitrogen deposition,and expand the research scope of leaf economic spectrum theory.