Estimating the effects of functional diversity and composition on the spatial variability of ecosystem multifunctionality in a large temperate forest region

Abstract Functional diversity and composition have been shown to significantly influence the temporal variability of ecosystem functioning. However, their impact on the spatial variability of multiple ecosystem functions (multifunctionality) is still unknown. Therefore, this study aims to explore how functional diversity and composition affect the spatial variability of ecosystem multifunctionality (EMF-SV) under different environmental conditions in a temperate forest region. Regional communities representing specific spatial scales were established by assembling different numbers of sample plots. The EMF-SV was represented by the ratio of the standard deviation to the mean value of ecosystem multifunctionality within each regional community. Linear mixed-effects models were used to evaluate the effects of functional diversity and composition on the EMF-SV at different spatial scales. Structural equation models were applied to explore the direct and indirect pathways of functional diversity and composition influencing the EMF-SV. Our results show that functional diversity and composition had significant effects on the EMF-SV, and these effects changed with spatial scales and environmental conditions. They affected the EMF-SV directly or indirectly through species asynchrony and population stability. Our results demonstrate the role of functional traits in regulating the EMF-SV across spatial scales and explore the main impact mechanisms. This will contribute to our understanding and protection of ecosystem multifunctionality in temperate forests.