DISSERTATION RESEARCH: Carbon allocation strategies in understory native and invasive woody plants

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One of the largest management concerns in natural forests of the Eastern U.S. is the invasion of ornamental shrubs from Europe and Asia. These plants outcompete native species for resources, reducing plant species diversity and altering the cycling of forest nutrients. This project will explore differences in energy use between native and invasive shrub species to advance our understanding of when and why exotic plants will exclude native plants. Research findings will help forest managers make decisions that will best protect U.S. forests in the face of environmental change. The project will support the research and training of a doctoral student, expanding the student's experimental and analytical skills. Undergraduate students from underrepresented groups will participate in hands-on research; through this engagement, the research will foster a new generation of critically thinking young scientists. This project characterizes carbon allocation patterns in native and invasive woody plants growing in deciduous forest understories. It will evaluate the relationship between growth rates and carbon storage allocation, and how allocation to defense mediates this relationship. Researchers will test the general hypothesis that invasive plants allocate more carbon toward growth at the expense of storage allocation in order to outcompete native plants for resources. Storage compounds, in the form of starches and simple sugars, are critical for recovery from tissue damage and protection from frost events. Preliminary data show that invasive species have higher growth rates and produce more leaves in response to leaf removal, but it is unknown whether this comes at a loss of storage compounds that promote survival. An insect feeding experiment on a range of native and invasive species' leaves will be carried out to assess allocation to physical and chemical defenses, and a freezing experiment will elucidate the relationship between stem starch and sugar concentrations in different species and their ability to tolerate cold temperatures. These activities will test the hypothesis that invasive species possess lower carbon storage and defense allocation than native species, and that this difference leads to lower survival in response to leaf removal and freezing events, and lower resistance to herbivore feeding.