Using trophic network analysis to reveal impacts of plant diversity loss on above- and below-ground functions and ecosystem stability.



Oksana Buzhdygan, in cooperation with Jana Petermann and The Jena Experiment Group


The relationship between the loss of biodiversity and ecosystem functions has been shown predominantly for the separate specific levels of ecosystems, for example for primary producers. Yet, the effect of biodiversity losses is likely to depend on the complexity of the whole ecosystem impacted as a result of emergent properties. In the current project, it is proposed to integrate the holistic trophic-network approach into the framework of biodiversity-ecosystem functions relations by using an Ecological Network Analysis (ENA) tools applied to the empirical long-term and large-scale biodiversity experiment data on grassland ecosystems. With this study, we will elucidate the hidden effects of biodiversity loss on material and energy flows through the above- and below-ground trophic networks and ultimately its impacts on ecosystem stability.

The platform for the project is the large-scale empirical database on experimental grasslands “The Jena Experiment”, which is one of the longest-running biodiversity experiments in Europe. Within the project the above- and below-ground trophic networks (biomass-based flow webs) will be constructed and assessed for the 80 experimental grassland ecosystems (study plots), varying in plant species richness (1, 2, 4, 8, 16, and 60 species) and plant functional group richness (1, 2, 3, and 4 functional groups). The biomass dynamics of experimental grassland ecosystems will be modeled on a scale large enough to preserve meaningful ecological details and to produce an adequate analysis of large-scale complexity that exists as a fundamental property in real-world ecosystems.

The among-plot multicomparative analysis of the trophic functions (such as, cycling and homogenization of matter among the organisms; system indirect effects; development capacity and maturity of ecosystem; system benefit-cost properties) will generate empirical evidence for biodiversity-ecosystem functions relationships in terms of trophic dynamics of the study grasslands. Our results will give us important insights into how ecosystems, in respect to above- and below-ground trophic networks, respond to species extinctions, and more generally to stress. We must be able to understand the patterns of how and why changing plant diversity produces cascading changes at other trophic levels, as well as in total system trophic dynamics.

On the other hand, the comparison of the network properties among themselves will show which trophic functions are the most sensitive in response to biodiversity losses. Vice versa, the most tolerant of trophic properties will illuminate the ecosystem functions which help community to resist species extinctions. Consequently we will be able to understand ecosystem stability/instability patterns that are a result of changing biodiversity.


The project is funded under the Dahlem Research School's Postdoc Fellowship Program at Freie Universität Berlin within the DCPS Program – co-financed by the German Excellence Initiative and the Marie Curie Program of the European Commission.