Above- and below-ground biodiversity jointly regulate temperate forest multifunctionality along a local-scale environmental gradient

1. Tree diversity has been shown to promote a broad range of ecosystem functions in forests. However, how important these effects are in driving ecosystem multifunctionality in natural forests, relative to other drivers, such as below-ground biodiversity (e.g., soil microbial diversity), community-level functional traits and environmental conditions, remains poorly understood. Here, we hypothesise that tree species or phylogenetic diversity, stand structure, functional traits and soil microbial diversity jointly regulate temperate forest multifunctionality along a local-scale environmental gradient. 2. Using repeated census data from a 25-ha old-growth temperate forest, we first quantified eight ecosystem functions and properties related to above- and below-ground nutrient cycling. We then used these to estimate ecosystem multifunctionality using both an averaging and multiple thresholds (50, 75, and 95%) approaches. Finally, we used structural equation models to explore how differen...