EEB Student Dissertation Defense - The role of dominant plants, insects, and climate in shaping communities and ecosystems

Dissertation abstract:
Plant communities are structured by multiple potentially interacting factors, including interactions between plant species, herbivores, and climate. Critically, the independent and potentially interactive effects of plant-plant interactions, insect herbivory, and precipitation on plant community structure and ecosystem function are rarely investigated. My dissertation addresses this research gap through a set of three separate field studies in old fields across Michigan. First, I investigated the role of a dominant plant species in shaping plant species richness, productivity, and the community structure of associated arthropods. Specifically, I found that the dominant plant species Solidago canadensis (Canada goldenrod) indirectly reduced arthropod abundance by reducing the biomass of all of the other plant species in the community, in part by reducing light availability. With this work, I demonstrate that the effects of a dominant plant on communities spans across multiple trophic levels. Next, at the same field site, I implemented a field experiment to study the independent and combined effects of S. canadensis and insects on plant diversity, biomass, subdominant species abundance, microclimate, plant functional traits, and decomposition. Insect presence mediated the effect of S. canadensis removal on plant biomass and richness. Furthermore, the effects of S. canadensis and insects extended belowground and determined the temporal variability of plant biomass. Overall, these results emphasize the importance of considering the effect of insects when trying to understand the role of dominant plants in structuring plant communities and shaping ecosystem function above- and below-ground, as well as overtime. Finally, I examined the combined effects of a generalist insect herbivore and altered precipitation on plant biomass, richness, functional diversity, and the community averaged trends of a suite of plant traits. Altered summer precipitation and the presence of the generalist insect Melanoplus femurrubrum (Red-legged grasshopper) had interactive effects on the plant biomass and on community averaged plant traits, in particular. These results suggest that the traits of the most common species in the community are the most sensitive to altered precipitation and grasshopper herbivory. Taken together, my dissertation comprehensively examines the factors that structure plant communities, and in particular enhances our understanding of the interactive effects of dominant plants, insects, and climate on communities and ecosystems.

This is a hybrid event. Join Zoom Meeting
https://umich.zoom.us/j/94424914774
Meeting ID: 944 2491 4774
Passcode: plants