Drought neutralises plant–soil feedback of two mesic grassland forbs

• Published in: Oecologia Vol. 186; no. 4; pp. 1113 - 1125
• Main Authors: Fry, Ellen L., Johnson, Giles N., Hall, Amy L., Pritchard, W. James, Bullock, James M., Bardgett, Richard D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Science + Business Media 01-04-2018; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Climate Change; Conditioning; Drought; Droughts; Ecology; ECOSYSTEM ECOLOGY – ORIGINAL RESEARCH; Factorial design; Flowers & plants; Forbs; Grassland; Grasslands; Herbivores; Hydrology/Water Resources; Hypotheses; Interactions; Life Sciences; Microorganisms; Mineral nutrients; Nutrient availability; Nutrient uptake; Nutrients; Photosynthesis; Plant communities; Plant Sciences; Plant species; Plants; Scabiosa columbaria; Soil; Soil conditions; Soil microbiology; Soil microorganisms; Soil properties; Species; Uptake; Water demand; Soil; Plant functional traits; Resource capture; Plant–soil feedbacks; Drought
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-018-4082-x

Plant–soil feedbacks (PSFs) describe the effect of a plant species on soil properties, which affect the performance of future generations. Here we test the hypothesis that drought alters PSFs by reducing plant–microbe associations and nutrient uptake. We chose two grassland forb species, previously shown to respond differently to soil conditioning and drought, to test our hypothesis. We conditioned unsterilised grassland soil with one generation of each species, and left a third soil unconditioned. We grew a second generation consisting of each combination of plant species, soil, and drought in a full factorial design, and measured soil microbial community and nutrient availability. Scabiosa columbaria displayed negative PSF (smaller plants) under non-droughted conditions, but neutral under drought, suggesting that drought disrupts plant–soil interactions and can advantage the plant. Photosynthetic efficiency of S. columbaria was reduced under drought, but recovered on rewetting regardless of soil conditioning, indicating that PSFs do not impede resilience of this species. Sanguisorba minor showed positive PSFs (larger plants), probably due to an increase in soil N in conspecific soil, but neutral PSF under drought. PSF neutralisation appeared to occur through drought-induced change in the soil microbial community for this species. When S. minor was planted in conspecific soil, photosynthetic efficiency declined to almost zero, with no recovery following rewetting. We attributed this to increased demand for water through higher demand for nutrients with positive PSF. Here we show that drought neutralises PSFs of two grassland forbs, which could have implications for plant communities under climate change.