Main projects: Biodiversity - ecosystem functioning (BEF) relationships in multitrophic metacommunities (an SNF Ambizione project in colaboration with Eric Allan at UniBe)
This project aims to understand the complex relationship between biodiversity and ecosystem functioning (BEF). While many studies show a generally positive link between biodiversity and ecosystem functioning, this relationship is context-dependent. This project focuses on the context-dependency of BEF relationships, specifically in regard to multi-trophic interactions, eutrophication, and spatial processes and scales.
To foster our understanding of BEF relationships and their context-dependency, this project combines empirical data from a large grassland experiment (PaNDiv project) and grasslands in the Swiss Alps with a theoretical approach, e.g., bioenergetic food-web modeling. By integrating these methods, the project seeks to uncover the mechanisms driving BEF relationships and provide insights into questions such as optimal spatial configurations of plant communities for maximizing BEF. The ultimate goal is to develop a mechanistic understanding of BEF relationships that can be applied across different ecosystems and inform future ecological research and management practices.
This project focuses on following main questions and topics:
The structure of plant-herbivore networks and their implications for food-web dynamics and ecosystem functioning
Thisproject aims to understand how plant-herbivore interactions shape biodiversity-ecosystem functioning (BEF) relationships. The research will identify key plant and herbivore traits that predict trophic interactions and use these to build a trait-based network model. The project will rely on extensive empirical datasets of thousands of plant-herbivore interactions. Key traits, such as leaf thickness, mouthpart size, body size, feeding type, and nutrient content, will be used to generate network structures and phenomenologicaly parameterize functional responses. The resulting model will be integrated into a bioenergetic food-web framework to simulate biomass dynamics.The organization of food webs varies depending on species' specialization: specialist-dominated communities tend to form linear, "chainy" networks, while generalists create highly connected, "webby" structures. These differences affect energy fluxes and ecosystem functions like primary production. Highly connected food webs may lead to increased energy transfer to higher trophic levels, potentially reducing plant biomass, while weakly connected networks may be more stable. Using trait-based models, the project will compare different food-web structures and evaluate their impact on plant productivity, biomass, and herbivory rates.
Researchers: Leonardo Espinosa, Remo Ryser
In colaboration with Elisa Thébault, Martin Goßner
The interactive effect of food-web structure and nutrient availability on BEF relationships
This project explores how food-web structure and nutrient enrichment interact to shape biodiversity-ecosystem functioning (BEF) relationships. Using bioenergetic modeling and empirical data from the PaNDiv experiment, we investigate how different community compositions influence ecosystem stability and productivity under eutrophication. Network Structure & Eutrophication – Specialized food webs may collapse at lower nutrient levels, while generalist networks persist longer but risk sudden breakdowns. We assess how modularity and generality impact BEF relationships using models and empirical plant-herbivore data. Functional Plant Composition & Stability – Eutrophication destabilizes food webs, favoring certain species while causing extinctions. We test whether a mix of slow- and fast-growing plants with varied trophic interactions buffers these effects. By integrating modeling with real-world data, this project aims to clarify how eutrophication reshapes food webs and ecosystem functioning.
Researchers: Leonardo Espinosa, Remo Ryser
Multitrophic metacommunities in BEF research: the role of space and movement of organisms
This objective examines how spatial processes influence biodiversity-ecosystem functioning (BEF) relationships under eutrophication. Using a combination of empirical data from the PaNDiv experiment and a suite of meta-community models, we assess how the composition and nutrient status of neighboring communities affect ecosystem stability and productivity.Dispersal can either stabilize or destabilize food webs by redistributing biomass between nutrient-rich and nutrient-poor areas. We analyze empirical data and model different spatial scenarios to determine how spatial processes influence plant coexistence and BEF relationships, particularly in low-nutrient environments. Spatial Processes in High Beta-Diversity Systems – Colonization and species dispersal not only transfer biomass but also introduce new traits that shape species interactions. We investigate how plant community assembly, herbivore sharing, and biotic filtering affect BEF relationships in spatially heterogeneous environments, using both theoretical models and real-world PaNDiv data. By integrating spatial ecology with eutrophication research, this project aims to identify key spatial drivers of BEF relationships and inform strategies for enhancing ecosystem resilience.
Researchers: Remo Ryser
Scaling up: (how) can insights on BEF relationships gained at the experimental level be transfered to larger scales? A comparison to alpine meadow systems
While most grassland experiments occur at small spatial scales, their findings are often extrapolated to larger agricultural and natural ecosystems. This subproject evaluates the extent to which BEF relationships identified in controlled experimental plots remain valid at broader spatial scales. By adapting the trophic meta-community model, we simulate conditions matching two large-scale mountain meadow fertilization experiments in the Swiss Alps. Using empirical data from these long-term experiments, we assess how spatial dependencies shift when moving from small plots to entire meadows. We expect that key ecological processes—such as species dispersal and the mitigating effect of neighboring communities on eutrophication—may be scale-dependent. This work will help identify which mechanisms maintain their influence across scales and which require reconsideration when applied to real-world agricultural systems.
Researchers: Remo Ryser
In colaboration with Jean-Yves Humbert
Combining theoretical and empirical research - where do we stand with bioenergetic (meta-)food-web modelling?
This project aims to synthesize a biologically realistic trophic meta-community model capable of predicting empirically observed BEF relationships. By integrating multiple ecological processes—including species interactions, movement, home range size, and dispersal, this model will capture spatial dynamics across different scales. The model will be calibrated using data from the PaNDiv experiment, allowing direct comparisons between simulated and empirical results. By systematically switching ecological processes on or off, we can determine the key mechanisms driving BEF relationships. Sensitivity analyses will ensure robust hypothesis testing, providing insights into which processes shape ecosystem responses and what additional empirical measurements could help refine our understanding. This synthesis will offer a powerful tool for exploring biodiversity-functioning dynamics in spatially structured ecosystems.
Researchers: Remo Ryser
Other projects:
Bioeconomics in fisheries
In this project, we combine bioenergetic food-web models with economic models to understand how ecological and economic dynamics interact and test how different fishing strategies affect ecological and economic stocks and yields and their stability.
Researchers: Remo Ryser
In colaboration with EcoNetLab and iDiv
sMars - Synthesis of Movement Across Scales (an sDiv funded research group):
Movement is the key process driving species interactions, community composition, and ultimately biodiversity patterns across scales. However, the geographic scale of biodiversity research does not necessarily match the scale at which animals move and interact. Thus, we are developing an empirically informed unified concept of spatial scale that accounts for the differences in how species experience their spatial environment. Furthermore, we are compiling a general movement database and are developing a mechanistic dispersal model based on energy budgets and metabolism.
Researchers: Remo Ryser
In colaboration with Myriam Hirt
Past projects:
Artificial light at night (ALAN)
Artificial light has a major impact on nocturnal animals and plants and has hence gained increased attention from the global change research community. During my bachelor's and master's studies, I conducted extensive fieldwork on how artificial light impairs plant-pollinator networks. After receiving my PhD, I took up this interest again at iDiv. Here, we created a artificial light experiment (EcoLux) on the iDiv EcoTron experimental platform. Due to the collaborative nature of the project, we were able to holistically measure ecosystem patterns and processes ranging from below-ground microbes to plants and invertebrates. This project furthermore sparked a thematic session at the BES2021 that I organized and chaired. Following this, I contributed to and edited a theme issue on “Light pollution in complex ecological systems” for the Philosophical Transactions of the Royal Society B.
Networks on Networks
During my PhD, I developed a bioenergetic meta-food-web model by extending an allometric trophic network model (ATN) into a spatially explicit framework by coupling local food-web dynamics on patches through dispersal. One, in my opinion, particularly interesting insight from this model was a mechanistic explanation of how habitat heterogeneity can foster biodiversity through the well-known rescue effect and its counterpart that we named the "drainage effect".