Katarina Hedlund

Agricultural intensification and extreme weather events can represent considerable stress to soil microorganisms and their functions by influencing the key players behind the degradation of soil organic matter. A better understanding of the diversity and abundance of microbial functional genes that predict the functional potential of soils, can link the microbial communities to their key ecosystem functions. As there are still gaps in understanding how the functional genetic diversity behind microbial extracellular enzymes is influenced by events like drought and soil carbon management, an agricultural experiment over a range of different climatic conditions and soil properties was set-up across Europe. In Sweden, Germany and Spain, fields with varying levels of soil organic carbon were subjected to a short-term experimental drought. The diversity and composition of genes encoding for carbohydrate-related extracellular enzymes were determined using a ‘captured metagenomics' technique. Functional gene diversity differed among the European regions and to a range of soil factors such as organic carbon and water content. The functional and taxonomic gene composition significantly differed between the climatic regions, while an effect of short-term drought was only observed in Germany. The results indicate that some soil microbial communities and their functional genes displayed a certain degree of resistance. The results suggest that soil microbial communities respond differently to short-term drought mainly due to regional adaptations to already dry environments and differences in their soil physicochemical properties.