Land Use Effects on Grassland Drought Tolerance
The increasing frequency and intensity of drought events is threatening productivity and carbon storage in semi-natural grasslands used for livestock production. Ancient grasslands are characterized by high biodiversity, which is known to enhance drought resilience, but most grasslands represent younger communities established on ex-arable land. How grassland age shapes drought response remains poorly understood. Besides changes in species richness and composition, soil microbial communities and local adaptation processes within plant populations may also contribute to drought resilience but are rarely assessed. Superior drought resilience in ancient grassland soils was associated with changed composition and reduced relative abundance of putative fungal pathogens in the soil. In addition, we found evidence for local adaptation as plants were more productive in their home than unfamiliar soils, and the home advantage was more pronounced in soils with lower pathogen abundance. Our study emphasizes the importance of conserving ancient grasslands to sustain ecosystem functions under changing climate and highlights the significant role of soil microbial communities in shaping grassland drought resilience. Our study comprised 15 grassland sites spanning a 300-year-long successional gradient on the island of Oland, Sweden. Soil DNA was extracted using the PowerMax Soil DNA Isolation Kit (MoBio Laboratories, Inc.) from a 5 g subsample of soil which was collected from each site and used for setting up the drought experiment. To characterise the soil fungal community composition, we amplified the target marker region of the ribosomal ITS2 using the degenerate primer pair fITS7:fiTS7o. The amplified ribosomal ITS2 regions were sequenced by Novogene Company (UK) using a 2 x 250 bp paired-read sequencing approach on an Illumina NovaSeq platform.