SP11: Networks and energy fluxes

点击翻译按钮获取中文摘要

SP11 addresses the quantitative structure and stability of soil food webs along the plant diversity gradients of the Main Experiment and the ResCUE Experiment of the Research Unit 5000. The project is based on the assumption that changes in plant community diversity and composition exert bottom-up effects on the structure of and energy flux through soil food webs. The project builds heavily on the results of the previous phase of the Research Unit, but now focuses on (1) the role of plant diversity for the temporal (seasonal) and spatial (depth distribution) stability of the structure of belowground communities investigated in the framework of the Main Experiment (WP1), (2) the role of plant diversity for the temporal (seasonal) and spatial (depth distribution) stability of energy channelling through belowground communities investigated in the framework of the Main Experiment (WP2), and (3) the response of the structure of and the energy flux through the belowground community to plant diversity and a hot drought disturbance investigated in the framework of the ResCUE Experiment (WP3). As in the first phase of the Research Unit, the energy-flux analyses will be focused on broad functional groups, such as primary and secondary decomposers, herbivores, as well as predators. This will be complemented by more detailed analyses using compound-specific analysis of stable isotopes of amino acids allowing to separate the fluxes into the bacterial-, fungal-, and plant-based energy channels. The resulting data will provide unique insights into variations in the energetic structure of soil food webs as affected by plant diversity. Differences in energy fluxes to belowground consumers will result in significant feedback effects that will be key to mechanistically explain biodiversity–ecosystem function relationships through multi-trophic interactions. Investigations in the framework of the ResCUE Experiment (WP3) will complement the studies in the Main Experiment (WP1 & WP2) by focussing on the response of the belowground food web to a strong disturbance (drought) by plant diversity. Using the iDiv Ecotron facility in this experiment will allow to follow effects of drought on the incorporation of plant carbon (using pulse labelling with 13CO2) and fertiliser nitrogen (using 15N labelled fertiliser) into the belowground food web and to investigate if this is mitigated by plant diversity. Therefore, WP3 will add new dimensions to the investigation of the role of plant diversity for the stability of the structure and functioning of the belowground food web.