BExudation - Integrating exudation into the root economics space to better understand carbon and nutrient cycling in managed grasslands

• Applicants: Dr. Joana Bergmann; Dr. Maire Holz
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569064921

From a plant perspective fine-roots are the entry point for soil nutrients while leaves are the entry point for carbon (C). From a more systemic point of view though, C is transported from the atmosphere to the soil not only as a structural element of roots but in the form of different root exudates. Up to 21% of photosynthetically fixed C can be released by the plants into the soil as exudates, making it a major C flux with strong implications for ecosystem functioning. Despite its importance, root exudation remains underrepresented in trait-based frameworks like the root economics space (RES) which currently focuses on morphological root traits and plant strategies along conservation and collaboration gradients. The RES conceptualizes root strategies along two axes: the conservation gradient (fast vs. slow traits) and the collaboration gradient (direct uptake vs. mycorrhizal outsourcing). With the higher aim of providing insights into C and nutrient cycling in managed grasslands, we aim to include root exudation into the existing framework of the root economics space. We will perform a large greenhouse experiment on 80 species from the Biodiversity Exploratories to determine species specific exudation rate and chemical composition. For each species, we will quantify exudation rates and chemical profiles - focusing on sugars, amino acids, carboxylates, and phenolics - under standardized conditions. These data will be combined with core root morphological traits and mycorrhizal colonization to build a comprehensive trait dataset. These data will be used to 1) expand the root economics space concept for the missing information on exudates, 2) study the filter effects of soil environmental parameters and land use effects on plant functional biodiversity and 3) investigate the effect of plant-community exudation patterns on ecosystem functions like productivity, C and nutrient cycling and greenhouse-gas emissions. Through this integrative and interdisciplinary approach, the project will close a critical knowledge gap in trait-based plant ecology. It will provide mechanistic insights into how root exudates mediate plant–soil interactions and contribute to C and nutrient dynamics in managed ecosystems. The resulting data will not only extend the conceptual framework of the RES but also enhance our ability to predict how plant communities respond to environmental change and how their traits influence ecosystem processes.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories