Biodiversity Consistently Promotes Ecosystem Multifunctionality Across Multiple Temporal Scales in an Aquatic Microbial Community

Biodiversity is essential for sustaining ecosystem multifunctionality (EMF), yet its role in natural ecosystems remains uncertain because various environmental drivers, alongside biodiversity, influence EMF, complicating the empirical biodiversity–EMF relationship. Additionally, the effects of biodiversity and environmental drivers on EMF likely vary across temporal scales, making this relationship inherently scale-dependent. Over nine years, we conducted a biweekly sampling, measuring microbial diversity, EMF (via 31 carbon utilisation functions), and various environmental variables in a subtropical freshwater ecosystem. Our analysis across inter-annual, seasonal, and short-term scales revealed that biodiversity consistently enhances EMF at all scales, while environmental drivers such as precipitation, temperature, and phosphate influenced EMF only at specific scales (short-term, seasonal, and inter-annual, respectively). Importantly, biodiversity mediated these environmental impacts, reinforcing its central role in maintaining EMF. These findings highlight biodiversity as a critical pillar for EMF across scales, underscoring the importance of conserving biodiversity to sustain EMF amid multifaceted environmental changes.