Tree diversity across multiple scales and environmental heterogeneity promote ecosystem multifunctionality in a large temperate forest region

Abstract Aim Biodiversity across different scales provides multidimensional insurance for ecosystem functioning. Although the effects of biodiversity on ecosystem multifunctionality are well recorded in local communities, they remain poorly understood across scales (from local to larger spatial scales). This study evaluates how multiple attributes of biodiversity maintain ecosystem multifunctionality from local to regional scales, across diverse environmental gradients. Location North‐eastern China. Time Period 2017. Major Taxa Studied Woody plants. Methods We define multifunctionality using both averaged and modified multiple‐threshold approaches. Multiple dimensions of biodiversity across varying spatial scales were measured within the framework of Hill–Chao numbers. Using variance decomposition, linear mixed models and structural equation modelling, we explored how multiple attributes of tree diversity at varying spatial scales affect multifunctionality, and how these relationships are modulated by environmental drivers. Results We found that both α‐ and β‐diversity are critical for regional community multifunctionality, while the relationships between species, functional and phylogenetic diversity and multifunctionality decoupled across spatial scales and thresholds of ecosystem functioning. Phylogenetic β‐diversity and species α‐diversity are, respectively, more important for promoting high‐ and moderate‐threshold multifunctionality (e.g. EMF T90 and EMF T50 ) in regional communities. Environmental drivers typically have stronger effects than biodiversity on multifunctionality. Soil and climatic conditions had either direct effects on multifunctionality or indirect ones mediated by species α‐diversity. Environmental heterogeneity is important for high‐threshold multifunctionality, exerting directly and indirectly through phylogenetic β‐diversity. Latitude not only directly influences multifunctionality but also modulates it through species α‐diversity and phylogenetic β‐diversity. Main Conclusions This study underscores the positive effects of biodiversity on multifunctionality across multiple dimensions. Based on our findings, we conclude that any design of a forested landscape that is aimed at maximizing multifunctionality should consider maintaining high local diversity as well as forest community heterogeneity at varying scales.