Final Report Summary - SOILMICROPLANTDIVER (Understanding soil microbially mediated mechanisms that influence plant species co-existence in natural communities) This project (terminated early because Dr Antunes accepted an offer for an Associate Professorship/Research Chair in Canada) aimed to increase our understanding of the factors that determine plant species success, particularly focusing on the many interactions that plants establish with soil microorganisms. Some of these interactions significantly increase plant growth and fitness while others involve pathogens, which cause opposite responses. The main long-term objective of the project was to understand the roles of the soil biota in natural ecosystems. More specifically, to characterise the potential of arbuscular mycorrhizal (AM) fungi and plant-AM fungal-pathogen interactions for influencing plant community structure. Even though the project was terminated prematurely, covering only approximately one year, the work carried out met several of the research objectives laid out at the onset. First, a critical analysis of the literature was undertaken in an attempt to identify mechanisms that enable certain beneficial microbial groups, such as the widespread AM symbiosis, to promote plant growth through pathogen-mediated protection. This work was recently published in an international peered review journal (see below). In collaboration with the group of Professor Florian Jeltsch (specifically with Mr Michael Ristow, a field botanist in his group) at the Institute for Biochemistry and Biology of the University of Potsdam, the plant community structure of a natural grassland near Berlin, Germany (Mallnow Nature Conservation site) was characterised. This effort allowed us to initiate experiments with selected plants species from grassland to test whether they receive pathogen protection from the AM fungal symbiosis and to what extend such interaction is a factor in plant-soil feedback. We found that assemblages of beneficial and pathogenic soil microbial communities may be important determinants of plant community structure in nature. The research indicated that in order to better understand soil microbiota effects on community structure, future approaches should focus on both beneficial and pathogenic groups simultaneously, because their effects are not independent of each other. This work was recently submitted for publication in the Journal of Ecology.The results obtained through the project may be relevant for policymakers that focus on habitat protection and conservation. They are also relevant to the public that is increasingly becoming aware of ecology and how species interactions are valuable in maintaining local diversity and, thus, all the associated unique goods and services.This project allowed the training of highly qualified personnel. One graduate student (who first-authored two publications) and several research technicians were involved. In addition, many undergraduate students that became aware of plant-soil-microbe interactions and their relevance in plant communities through the talks given during the project.