Collaborative Research: Role of soil microbiome resilience in ecosystem recovery following severe wildfire

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Wildfire is a natural feature of healthy forest ecosystems. There is concern because the frequency and intensity of these events are increasing as our climate warms. Among their many impacts, wildfire disturbances impact the microorganisms present in forest soils that catalyze a series of key ecosystem processes, ranging from the establishment of tree seedlings to the cycling of carbon and nitrogen. Research to date has revealed that the composition of soil microbiomes is altered by wildfire, but critical information is lacking on how increasingly severe wildfires in western US forests will affect the recovery of soil microbial communities, with cascading impacts on forest ecosystems. This research uses a unique series of burn pile scars in a lodgepole pine forest in northern Colorado as a proxy for the decadal recovery of the soil environment following severe wildfire. The work will use diverse microbiological and geochemical analyses to determine how soil chemistry and microbiomes change up to 50-years following fire. Insights gained here will assist with forest management following severe wildfire in the western US and will be incorporated into new educational opportunities at the participating research institutions. The project will enrich a variety of courses taught by the researchers, include training opportunities for undergraduate and graduate students, and provide cooperative extension to forest managers as well as public outreach activities.There is an increasing appreciation that changing wildfire regimes may drive long-term alterations in both above- and below-ground ecosystem structure. This research will investigate the resilience of soil microbiomes (i.e., their ability to return to pre-fire levels) following severe wildfire in lodgepole pine forests, (2) the functional implications of shifts in microbiome structure, and (3) the ability of altered soil microbiomes to support tree regeneration via rhizosphere interactions. Together, this research will test the hypothesis that altered soil chemical and physical properties drive the soil microbiome to an alternate steady state following severe wildfire, with implications for the establishment of new pine seedlings and subsequent ecosystem recovery. To test this, the work leverages a unique experimental opportunity consisting of burn pile scars throughout a forest ecosystem, thus ensuring that the chrono-sequence controls for fuel type and load, elevation, climate, and aspect. Furthermore, the approach integrates diverse analytical tools including metagenomic interrogations of soil microbiomes, mass-spectrometry characterization of soil chemistry, and vegetation manipulation greenhouse experiments. Together, our results will represent the first insights into the extent of resilience of burned soil microbiomes across a 50-year post-fire recovery period, and the ability of lodgepole pine seedlings to recruit beneficial rhizosphere communities that aid in tree re-establishment.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.