| 论文摘要： |
Biodiversity plays a critical role in regulating ecosystem functions in the context of global environmental change. However, current understanding remains disproportionately focused on single-trophic-level diversity and function, overlooking the importance of multi-trophic diversity and species interactions in driving multiple ecosystem functions, particularly in freshwater ecosystems. Here, we conducted a full-factorial mesocosm experiment to investigate the effects of three environmental stressors-nitrogen and phosphorus enrichment, dissolved organic carbon input, and fish disturbance-on ecosystem multifunctionality (EMF). All pairwise and three-way interactions in experimental treatments exhibited strictly additive effects on EMF. Linear regression analysis revealed that species richness and co-occurrence network complexity across multi-trophic levels (phytoplankton, zooplankton, and planktonic bacteria) have significant positive correlation with EMF. Structural equation modeling (SEM) further demonstrated that models incorporating multi-trophic biodiversity and network complexity provided the most robust explanations for the observed EMF changes. Random forest models indicated that multi-trophic biodiversity had stronger predictive power than single-taxon biodiversity. Notably, multi-trophic network complexity outperformed biodiversity alone in predicting EMF, highlighting the critical role of species interactions in determining EMF. Our results advance ecological theory by demonstrating multitrophic network complexity involving multi-trophic richness and species connectivity as a critical determination of EMF, which provides a mechanistic framework for freshwater conservation prioritizing cross-trophic network topology rather than mere species counts. |
