Microbial landscapes: Are microorganisms hidden drivers of species distributions?

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All plants live in places filled with many microbes, like bacteria and fungi, that are invisible to the naked eye. These microbes can help or hurt the plants they live with. For example, some microbes help plants grow in places without many nutrients, while other microbes cause disease. Given humanity's dependence on plants for food, shelter, clear air and fuel, understanding how microbes affect plant health is important, especially as the environment changes. This research will test how soil microbes help or hurt individual plants and how they may determine where groups of plants are found together. The goal is to see if microbes act as "hidden players" that explain patterns long thought to be explained by other things. Understanding microbial effects on plants can also improve how rare plants are managed and conserved, which is relevant because this project will take place in an area with many rare species. The project will provide training in field research for the next generation of scientists, including students from underrepresented groups at the University of Miami. Researchers will work with public school teachers to create nature documentaries and teaching modules to help middle school students learn about the hidden but important role of microbes in the world around them. This project has three main components. The first is to examine the interaction between well-known selection pressures (fire and allelopathy) and soil microbes on individual plant fitness. Next-generation sequencing will be used to determine how the soil microbiome responds to fire and allelopathy. Then, greenhouse experiments will be used to disentangle the role of differences in the soil microbes from differences in soil properties (and the interaction between the two) in governing plant fitness. The second component of the project will combine bioassays determining the effect of soil microbes on plant demographic parameters with existing long-term datasets to examine the demographic pathways and ecological contexts that allow microbes to influence plant population and metapopulation dynamics. This approach will use integral projection modeling to integrate microbial effects and patch-specific environmental parameters to understand the mechanistic basis for the distribution of 11 plant species across a patchy landscape. The final component will incorporate next-generation sequencing of soil microbiomes from ~700 sites into plant species distribution models to examine the relative importance of microbial and abiotic factors in determining the distributions of all ~80 members of the local plant community. Taken together, these new applications of modeling species distributions, demography, and metapopulations, parameterized with data from long-term studies and experiments, will shed light on the important linkages between plant distributions and their microbial associates.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.