BRC-BIO: Tracing Impacts of Invasive Woody Plants on Lake Food Webs

About This Grant

Invasive woody plants threaten ecosystems across North America. Some Eurasian species, such as Amur honeysuckle and autumn olive, are rapidly spreading, and understanding their relative impacts is essential for devising management plans that prioritize those species that pose the greatest risk. This project will examine how invasive plants affect aquatic ecosystems in the Iowa Loess Hills, a unique ecoregion of bluffs and ravines carved from one of the world’s deepest silt deposits. The area’s lowland ponds and streams provide important habitat for various species, including sport fish like largemouth bass. Every autumn, leaf litter from surrounding forests accumulates in these water bodies, serving as food for aquatic organisms. However, the quality of this food likely depends on the plant species and their leaf characteristics. In this project, researchers will quantify leaf traits from a variety of species and trace their relative contributions to aquatic food webs, with the goal of determining how the unique characteristics of invasive woody plants shape their impacts. Furthermore, the project will engage nine undergraduate students in hands-on research, providing them with valuable skills for future careers. Finally, public involvement will be promoted through Citizen Science, allowing local communities to participate in data collection and gain insight into the study’s findings and broader applications. To address these research questions, the researchers will (1) quantify the relative influence of leaf litter subsidies from native and invasive woody plants on freshwater food webs and (2) explain these differences in terms of leaf litter traits and the biotic interactions with aquatic invertebrates and microbes within the recipient communities. Field surveys and experiments will be used to compare inputs and decomposition rates of leaf litter from native and invasive woody plants in three small lakes. Furthermore, a combination of bulk and compound-specific stable isotope analysis (δ13C, δ15N, and δ2H) will be used to trace the contributions of organic material from different plant species to the aquatic invertebrate community that serves as the basis for higher trophic levels. These results will be complemented by comprehensive measurements of leaf traits to explain differences in decomposition, and thereby accessibility, of leaf litter between different species. Finally, laboratory microcosm experiments will be used to determine the roles of aquatic invertebrates and microbes in mediating decomposition of leaf litter from native and invasive woody plants. 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.