Quantifying the microbial contribution to community recovery from drought

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Understanding how ecological communities recover from extreme weather events can improve our ability to manage and enhance their productivity and services. Extreme droughts are predicted to increase in many regions, and may be critically important in arid and semi-arid drylands, which are often more sensitive to drought than wetter ecosystems. This project leverages previously NSF-funded infrastructure for creating experimental drought in dry grasslands in order to determine how much soil microbes aid in the recovery from extreme drought. Prior research has uncovered two key results that have yet to be united in contemporary research. First, drought leaves a legacy in the soil by changing the composition of microbes; this legacy can persist long after drought has ended. Second, additions of microbes can speed community recovery after disturbance. Combined, these two results suggest that soil microbes could drive the pace of ecological recovery from drought, but experimental studies are needed. This project will use microbial experiments in the field and greenhouse to determine the magnitude of drought impacts on drylands and elucidate how much soil microbes matter to recovery and resilience. This project trains the next-generation of diverse scientists by supporting a female Hispanic postdoctoral researcher, two female graduate students (one Hispanic), and independent research experiences for undergraduates, including partnership with the Southwestern Indian Polytechnic Institute. A new inquiry-based laboratory module reaches biology majors at a Hispanic-serving institution, and a drought-focused K-12 unit enhances next-generation science standards. The project has global importance because drylands occupy a large (~45%) and rapidly expanding percentage of land area and contribute greatly to global carbon fluctuations. Nearly 40% of people live in the world's drylands, and improved understanding of the processes by which drylands recover from drought may enable rapid restoration via microbial amendments, delivering new land management strategies. This project addresses the ecological question: How do microbes promote the recovery of plant communities and ecosystem functions following drought? While prior studies have documented the legacy effects of climate disruptions, the proposed work would be among the first to use microbial experiments to quantify how much microbes contribute to the recovery process. This project manipulates surface microbes (biological soil crusts) and soil microbes to evaluate their influences on ecological recovery from experimental drought. A microbial reciprocal transplant experiment will test how restoration of pre-drought microbes speeds recovery relative to microbes with a drought legacy. A fungal loop experiment will evaluate whether fungal networks that link surface biocrusts with plant roots promote faster recovery than if these networks are disrupted. Finally, a greenhouse plant-soil feedback experiment will determine whether drought intensifies (or weakens) feedbacks that affect the resilience of plant productivity. The project generalizes to dry grasslands worldwide by including variation in plant life history, growth form and resource requirements, as well as variable microbial compositions and edaphic contexts. Research activities integrate evolutionary processes (drought alters genotype frequencies in dominant producers), community dynamics (of both plant and microbe assemblages), and ecosystem processes (soil carbon and nutrients) to elucidate the pathways through which microbes contribute to recovery from extreme weather events.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.