O'Connell, Erin2020-05-042020-05-042019-01https://hdl.handle.net/11299/213045University of Minnesota M.S. thesis January . 2019. Major: Integrated Biosciences. Advisor: Jessica Savage. 1 computer file (PDF); v, 66 pages.Many woody invasive plants in North America develop leaves earlier and retain leaves later than their native associates, which could result in greater carbon gain. However, freezing temperatures and low light levels at northern latitudes constrain growing season length, potentially reducing the importance of spring and fall carbon gain. To investigate the costs and benefits of extended leaf phenology, I observed two years of leaf phenology and for one year estimated total carbon gain, measured growth, and tested the freezing tolerance of four native and four invasive woody shrubs growing in Duluth, MN. I conducted my study in a disturbed forest with greater canopy openness than commonly studied late successional forests, in order to explore these traits in a habitat typical of invasive species. The invaders leafed out simultaneously with native species in the spring and demonstrated an equally high freezing tolerance, but retained their leaves later in the autumn. In addition, invasive species assimilated less carbon during the summer than the native species. Therefore, extended fall phenology in invaders was critical to maintaining competitive levels of carbon gain and did not provide an advantage over native species. These findings suggest that invasive species may be able to take advantage of lengthening growing seasons and that freezing temperatures do not currently limit their northern expansion. Continued research should consider geography and latitude when studying woody invasive species phenology and physiology.encarbon gainfreezing tolerancegrowthinvasive speciesphenologyplant physiologyThesis or Dissertation