Uncovering the mechanisms underpinning divergent environmental change impacts on biodiversity and ecosystem...

Environmental change drivers (ECDs) impact ecological communities in various ways, from enrichment that increases species' performance and abundance, to stressors that reduce their reproduction and growth. These effects can affect species coexistence as well as impact ecosystem functioning and the relationship between biodiversity and ecosystem function (BEF). Predicting the impact of ECDs on communities and BEF relationships requires understanding how ECDs affect fundamental population parameters, including intrinsic rate of increase (r), carrying capacity (K), and interspecific interactions ( $$ ). Here, we use numerical simulations based on theoretical models to show the explicit links between these parameters and the nature of BEF relationships. Depending on the mean and variance of the effects of ECDs on community members, BEF relationships increase or decrease in both their intercept and slope. We further derive hypotheses about how BEF relationships will be affected by multiple ECDs or when we consider multiple ecosystem functions. Our simple approach to understanding how ECDs affect BEF relationships provides a robust framework to explain why disparate studies and meta-analyses come to opposing conclusions about resilience or sensitivity of BEF relationships to anthropogenic influences. We show that modeling approaches offer a generalized and predictive understanding to guide biodiversity conservation, restoration, and green infrastructure design under environmental change.