• Energy Research

AbstractThe strength of biodiversity–ecosystem functioning (BEF) relationships varies within and across studies, depending on the investigated ecosystem function and diversity facet (e.g., species richness or functional composition), limiting our ability to translate BEF results into recommendations for management and conservation. The variability in BEF relationships is particularly high when considering complex multitrophic communities and can be explained by food web contexts. Here we examine how different plant diversity facets affect biomass stocks and energy flows of each trophic group depending on their position in the trophic network. We used coupled aboveground–belowground multitrophic networks of energy dynamics, assembled across the experimental gradients of grassland plant species richness, functional diversity, and presence of plant functional groups. We compared the strengths of these diversity effects between trophic groups, trophic levels, aboveground versus belowground subnetworks, and types of ecosystem functions. Plant species richness, functional trait diversity, and the presence of legumes and grasses were influential drivers of ecosystem energetics. The effects of plant species richness across the food web often operated through mechanisms of plant functional‐trait diversity. The effects of plant species richness attenuated across trophic levels. Legume presence strengthened the top‐down control (predation) of primary consumers. We found an overall mismatch in the strength of diversity effects on flows versus stocks. Some trophic groups showed even contrasting direction in responses of their stocks and flows to plant diversity. This indicates that plant diversity constrains consumer functioning by means other than only altered consumer biomass. Responses of flows and stocks to plant diversity differed between trophic groups, and aboveground versus belowground parts. Individual stocks and energy flows were responsive to different biodiversity facets, highlighting the importance of the explicit consideration of individual functions and diversity facets for a comprehensive multitrophic understanding. For example, legume presence increased aboveground processes but reduced plant carbon uptake and belowground plant production. Plant communities containing legumes lost more biomass to herbivores, had faster decomposition, and channeled less energy to soil detritus. An important implication of these results is that targeted grassland management would profit from focusing on specific plant diversity facets depending on the ecosystem function or service of interest.

AbstractNetwork ecology provides a systems basis for approaching ecological questions, such as factors that influence biological diversity, the role of particular species or particular traits in structuring ecosystems, and long-term ecological dynamics (e.g., stability). Whereas the introduction of network theory has enabled ecologists to quantify not only the degree, but also the architecture of ecological complexity, these advances have come at the cost of introducing new challenges, including new theoretical concepts and metrics, and increased data complexity and computational intensity. Synthesizing recent developments in the network ecology literature, we point to several potential solutions to these issues: integrating network metrics and their terminology across sub-disciplines; benchmarking new network algorithms and models to increase mechanistic understanding; and improving tools for sharing ecological network research, in particular “model” data provenance, to increase the reproducibility of network models and analyses. We propose that applying these solutions will aid in synthesizing ecological subdisciplines and allied fields by improving the accessibility of network methods and models.

Nature Ecology & Evolution, 4 ISSN:2397-334X

AbstractSpecies extinctions are accelerating globally, yet the mechanisms that maintain local biodiversity remain poorly understood. The extinction of species that feed on or are fed on by many others (i.e. ‘hubs’) has traditionally been thought to cause the greatest threat of further biodiversity loss. Very little attention has been paid to the strength of those feeding links (i.e. link weight) and the prevalence of indirect interactions. Here, we used a dynamical model based on empirical energy budget data to assess changes in ecosystem stability after simulating the loss of species according to various extinction scenarios. Link weight and/or indirect effects had stronger effects on food‐web stability than the simple removal of ‘hubs’, demonstrating that both quantitative fluxes and species dissipating their effects across many links should be of great concern in biodiversity conservation, and the potential for ‘hubs’ to act as keystone species may have been exaggerated to date.