Integrating food webs and food security to understand the impact of biodiversity loss on ecosystem functions and services

Accelerating biodiversity change is a defining characteristic of the Anthropocene, and evidence accumulated from almost 30 years of research is often invoked to suggest that these changes will have catastrophic effects on ecosystems and the services they provide to humanity. In this thesis I use theory, empirical analysis and their combination to address key remaining issues surrounding the relationship between biodiversity, ecosystem function and ecosystem services. First, while the asymptotic relationship between biodiversity and ecosystem function is substantiated from experiments that randomly assemble plant communities, the response of ecosystems to directional biodiversity loss is highly variable. In the first two chapters I investigate how species level attributes (vulnerabilities, functional contributions) and community dynamics (compensation, non-random extinction) scale to affect individual and multiple ecosystem functions simultaneously. Second, a narrow set of plant-based ecosystem functions have come to dominate the field, and with few exceptions, linking these to the ecosystem services that directly affect human well-being has been challenging. Inland fisheries provid