2020 ESA Annual Meeting (August 3 - 6)

COS 244 Abstract - Microbial community structure in recovering forests of Mount St. Helens

Mia Maltz, University of California Irvine; Center for Conservation Biology, University of California, Riverside, Riverside, CA, Michala Phillips, Botany and Plant Sciences, University of California Riverside, Riverside, CA, Rebecca R. Hernandez, University of California, Davis, Davis, CA, Hannah Freund, Genetics, Genomics, and Bioinformatics, UC Riverside, Riverside, CA, Hannah Shulman, Microbiology & Plant Pathology, University of California, Riverside, Riverside, CA, Jon K. Botthoff, Center for Conservation Biology, UC Riverside, Michael F. Allen, Plant Pathology and Microbiology, University of California Riverside, Riverside, CA and Emma L. Aronson, University of California Riverside
Background/Question/Methods:

The type and abundance of biotic propagules and legacies present in recovering ecosystems are important variables for determining the trajectory of post-disturbance recovery processes. Soil microorganisms regulate biogeochemical cycling and interact with numerous plant and animal species, and thus may support successional pathways by performing numerous functions within severely disturbed ecosystems. The 1980 eruption of Mount Saint Helens had devastating effects on forested ecosystems, including destroying or burying soil microbes and severely impacting biotic communities. Because of the magnitude of this event, monitoring microbes following this severe disturbance may be particularly valuable. Although clear-cut forests were severely affected by the eruption, many organisms survived and likely influenced the trajectory of biotic community assembly. In our study, we not only compared the microbes in old growth and clear-cut forests, but also locations of historic short-term gopher enclosures. Indeed, the pocket gopher, Thomomys talpoides, served as a vector for moving plant propagules, microbes, and mycorrhizal fungi to the surface of pumice plains within the blast area and ashfall zone, creating microsite conditions conducive for primary succession and plant establishment. Using high-throughput sequencing, bioinformatics, and AMF biomass-allocation traits, we examined bacterial, fungal, and AMF communities from the historic locations of short-term gopher enclosures, and in depauperate locations within the Mount Saint Helens blast area, to determine how these variables affected microbial communities.

Results/Conclusions:

We found that bacterial/archaeal 16S, fungal ITS2, and AMF SSU community composition varied between forestry practices and between sites with lupine and gopher enclosures. Our findings suggest that the microbial communities from clear-cuts were less diverse than in remnant old growth forests, likely because of greater mixing of soils found within clear-cuts. Although our methods did not allow us to characterize the successional trajectory, we were able to examine differences in multiple components of the microbial community, as a result of land-use histories. By investigating the role of both forestry practices and small mammals in microbial dispersal, we were able to evaluate how these interactions promoted revegetation and ecological succession within the pumice plains of Mount Saint Helens. In addition to providing valuable data on the influence of these variables on microbial communities, this research may also inform management strategies for promoting ecosystem recovery.