Ecological multifunctionality of watersheds increases with tree species richness

Abstract

Watersheds are natural units and meta-ecosystems of the earth’s land surface providing multiple ecological functions. However, little is known about the biodiversity-ecological multifunctionality relationships of watersheds, particularly regarding how these relationships scale to large and complex landscapes. Here, we explore the impact of forest tree species richness on the ecological multifunctionality of watersheds in terms of carbon sequestration, carbon storage, water supply, water regulation, and soil conservation, by utilizing integrated ground-sourced forest inventory datasets comprising 846 forest watersheds from the Global Forest Biodiversity Initiative, the Global Streamflow Indices and Metadata Archive, and remote sensing data products. We find a consistently positive relationship between forest tree species richness and watershed ecological multifunctionality by accounting for factors such as forest structural characteristics and environmental conditions. Furthermore, we find that this biodiversity-multifunctionality link is dependent on spatial scale and climatic context, becoming stronger in larger watersheds but diminishing in arid climatic conditions. These insights enhance our understanding of ecosystem multifunctionality and underscore the importance of considering watershed-scale ecological processes and biodiversity in ecosystem management and conservation strategies.