Relationship Between Plant Community Diversity And Ecosystem Multifunctional In Inner Mongolia Grassland

Global climate change is threatening biodiversity at an unprecedented rate in this century,elevating the importance of understanding the relationship between biodiversity and ecosystem function.Ecosystem multifunctionality,the ability of an ecosystem to sustain multiple functions at the same time,can provide more comprehensive information than the single ecosystem function.Research on the relationship between diversity and ecosystem multifunctionality has been a hot topic in recent years.However,previous studies were mostly limited to the single aspect or scale of diversity,the relationship between multiple aspects and scales of diversity to ecosystem multifunctionality remains unclear.In this study,194 sites set along the aridity gradient across the Inner Mongolia grassland.We investigated species,functional,and phylogenetic aspects of diversity at ? and ? scales,and measured four key plant functional traits reflecting plant ecological strategies(plant height,leaf area,leaf dry mass,specific leaf area)and eight ecosystem functions related to ecosystem cycle and storage of carbon,nitrogen,phosphorus(aboveground productivity,soil organic carbon,total soil nitrogen,total soil phosphorus,soil available nitrogen,soil available phosphorus,soil carbon-nitrogen ratio,and soil nitrogen-phosphorus ratio)at each site.Our study aims to comprehensively assess the relationship between multiple aspects and scales of plant diversity and ecosystem multifunctionality along an aridity gradient across the Inner Mongolia grassland.The main results are as follows:(1)Diversity and ecosystem multifunctionality tend to decrease as the increase of aridity from the southwest to the northeast in the Inner Mongolia grassland.(2)The diversity of species,functional,and phylogenetic aspects at the ? and ? scales are all significantly positively related to the ecosystem multifunctionality.(3)As for different aspects of diversity,functional diversity has the highest explanation power for ecosystem multifunctionality,explaining 52% of its variation,followed by species diversity,and explaining 16% of its variation.Phylogenetic diversity has the lowest explanation power for ecosystem multifunctionality,explaining 3% of its variation.(4)As for different scales of diversity,the combined effect of the diversity at ? and ? scales contributes to the multifunctionality best,explaining 34% of its variation.(5)Aridity has the direct and indirect effects on the ecosystem multifunctionality,of which the direct effect is-0.65,and the indirect effect is-0.45.The indirect impacts of aridity on multifunctionality were mediated by species and functional diversity.Species diversity does not directly affect ecosystem multifunctionality,but indirectly affects ecosystem multifunctionality by affecting functional diversity.The above results indicate that diversity at both ? and ? scales have an essential role in affecting ecosystem multifunctionality,and buffering the adverse effects of aridity.This study emphasizes the heterogeneity among communities(diversity at ? scale),especially the aspect of functional traits,which should receive more attention in Inner Mongolia grassland.