S-CLIMA · Drought impacts on plant-soil interactions and ecosystem stability

Soils and the communities within them have a central role in numerous ecosystem processes, including complex interactions with biotic and abiotic factors, such as climate. The mechanisms of how soil microorganisms interact with climate remain unknown and there may be ways of mitigating climate change impacts through manipulation of soil microbial processes. Mediterranean habitats are particularly threatened by climate change, and are predicted to experience an increase in annual average temperature, by up to 6oC in summer, and a 30-45% decrease in summer precipitation by the end of this century. This region is a conservation priority as it contains high plant diversity and a high percentage of endemic species. The predicted increase in extreme drought in this ecosystem could have wide-ranging impacts on both natural and agricultural habitats, including loss of biodiversity and land degradation. These negative effects will only be mitigated through a thorough understanding of the relationships between drought, plant communities and soil processes. Plants are linked with the soil community through root exudates, which are compounds released by roots into the soil that interact with other plants and microorganisms. However our understanding of the mechanisms behind these interactions is incomplete. In this project we aim to acquire a fuller understanding of the mechanisms of these interactions and the importance of soil communities for ecosystem stability. Specifically, the project has the following objectives:1) To describe the impacts of drought-driven changes in plant productivity and diversity on the soil community and below-ground plant traits.2) To characterise the interaction between soil fertility and drought on plant-soil interactions with a particular focus on demand for root exudates under low fertility.3) To understand the effect of extreme drought on plant-pathogen interactions, and how that in turn affects plant community composition.