TrophiCH
Studying Swiss Food Webs Across Space
Global changes have been well-documented to lead to the modification of species distributions. However, species in nature are not independent units but interact with each other to form complex ecological networks. Global change drivers like climate and land-use changes can lead to cascading effects on ecosystem functioning because of the trophic interactions in which species - especially keystone species - participate. Mapping the structure of these networks in space and time can help monitor and anticipate the consequences of global changes on biodiversity. However, to date, an understanding of how animal species interact with each other is lacking in Switzerland.
With this project, we aimed to generate a metaweb, a network of all possible interactions between species from a regional pool. Local interaction networks then serve as distinct subsets of the regional metaweb, similar to how local communities can be thought of as subsets of a regional species pool. Using this approach, the robustness of local networks to global changes can be quantified, and novel biodiversity change indicators can be developed to function alongside ongoing monitoring programmes.
To create an extensive metaweb across Switzerland, we first built an empirical metaweb of well-documented species, feeding groups (such as fungi and algae). Then, we used data with lower taxonomic resolution, combined with environmental data, to infer further interactions (Figure 2).
In collaboration with the Swiss Catchment Project, we will infer local networks at the scale of river catchments, which integrate biodiversity within their topographical structure. We can further compare these networks along large-scale abiotic gradients such as climate, topology and land-use intensity to better understand spatial patterns of biodiversity. For selected taxonomical groups where historical records are available, we will additionally investigate the temporal change in the metaweb.
The consequences of global changes are not limited to single species. In fact, the decline of one species can influence entire ecological networks. By comparing how networks change along environmental gradients and over time across the Swiss landscape, we can better understand and predict how ecosystems react to global changes via their trophic interactions.
More details at: external pagewww.merinrejichacko.com
Associated publication
Reji Chacko, M., Altermatt, F., Fopp, F. et al. Catchment-based sampling of river eDNA integrates terrestrial and aquatic biodiversity of alpine landscapes. Oecologia 202, 699–713 (2023). external pagehttps://doi.org/10.1007/s00442-023-05428-4
