Food web diversity and ecosystem energetics

Food webs or the networks of feeding links, provide the basis for fundamental ecosystem functions, including energy and nutrient flows. However, the structural complexity of food webs has not been fully incorporated in ecosystem studies. While community ecologists focus on the diversity and structure of species interactions in food webs, ecosystem ecologists often investigate energy dynamics in simplified, chain-like trophic systems. It remains challenging to integrate biodiversity and structure of food webs with ecosystem energy and nutrient dynamics. Our research aims to develop such an integrated framework.

We ask: (i) How do biodiversity and network structure influence energy and nutrient dynamics within food webs? (ii) What determines the energy transfer efficiency across trophic levels? (iii) How do energetic and stoichiometric constraints shape the diversity and functioning of food webs? We address these questions by combining theoretical models, field surveys and manipulative experiments.

Biodiversity and ecosystem stability across spatial scales

Biodiversity is not only declining in many local ecosystems, but is also becoming increasingly homogenized across space. Although the negative effects of biodiversity declines on ecosystem functioning and stability have been well documented, the effects of biotic homogenization are less understood. To address this issue, we have developed a theoretical framework to study ecosystem stability across spatial scales, and used metacommunity models and empirical data to show that biotic homogenization impairs ecosystem stability at large scales. Our ongoing work aims to further understand ecological factors driving patterns of biodiversity and stability across scales.

We ask: (i) How do species coexist in heterogeneous landscapes? (ii) How do functional traits mediate species coexistence and ecosystem stability across spatial scales? (iii) Do biotic and abiotic factors regulate the spatial scaling of ecosystem stability? We address these questions using theoretical models and re-analyses of existing datasets.

Integrating mechanisms underlying the causes and consequences of biodiversity

The past decades have seen substantial progresses in understanding the causes and consequences of biodiversity change. In particular, modern coexistence theory offers a unified framework to understand the mechanisms of species coexistence (causes), and research on biodiversity-ecosystem functioning or stability provides insights on how species interactions regulate ecosystem functioning and stability (consequences). Yet, the causes and consequences of biodiversity are almost separately addressed in the literature. Our research attempts to bridge these intrinsically related, yet separated topics.

We ask: (i) How do mechanisms of species coexistence relate to those of biodiversity-functioning and biodiversity-stability relationships? (ii) How will environmental changes modulate all these mechanisms and alter the relationships between them? To address these questions, we develop theoretical models, conduct mesocosm experiments, and perform synthesis and meta-analyses.