Abstract Detail

Physiology & Ecophysiology

O'Connell, Erin [1], Savage, Jessica [2].

Testing for a Potential Trade-off between Freezing Tolerance and Growth Rate in Invasive Woody Shrubs and their Native Associates.

Early leaf-out provides the advantage of first access to spring nutrients, as well as exposure to light before canopy closure, but may render young leaf tissue susceptible to late frosts. Some plants account for this threat with physiological changes that result in higher freezing tolerance. This is a more expensive investment that often correlates with slower a growth rate. If a plant could leaf out early to extend its growing season and not experience frost damage, while still maintaining a high growth rate, it could increase its competitive advantage. In this study, we investigated whether invasive shrubs are less constrained than native shrubs by a potential trade-off between high freezing tolerance and high growth rate. We selected four invasive shrubs (Berberis thunbergii, Frangula alnus, Lonicera x bella, and Rhamnus cathartica) and the four most closely associated native shrubs (Cornus sericea ssp. sericea, Corylus cornuta, Rubus idaeus var. strigosus, and Viburnum lentago) at Bagley Nature Area in Duluth, Minnesota. We observed leaf phenology of ten individuals for each species during the 2017 growing season and found that there was no difference between average budburst date in the spring for native and invasive species (p > 0.05). In the fall, the invasive species leaves senesced an average of 22 days later that native species leaves (p < 0.01). Since freezing tolerance may constrain leaf phenology, we employed several metrics to assess freezing tolerance on multiple tissue types in a temporal manner. We froze bursting buds, newly unfolded leaves, and late-season mature leaves to multiple temperatures and used visual observations, electrolyte leakage, and chlorophyll fluorescence to measure freezing tolerance. Preliminary results suggest that invasive shrubs’ newly unfolded leaves experience 24% less freezing damage at -8ºC than native shrubs’ young leaves (p< 0.001). We also measured total growing season carbon assimilation, maximum photosynthetic capacity, specific leaf area, and branch elongation as metrics of growth rate and growth potential. Examining the strength of the trade-off between freezing tolerance and growth in invasive species, as compared to natives, will shed light on physiological investment strategies of invasive woody shrubs and help us predict future invasive species influence on native ecosystem biodiversity.

1 - University of Minnesota Duluth, Biology, 1035 Kirby Drive, Swenson Science Building 207, Duluth, MN, 55812, USA
2 - University Of Minnesota - Duluth, Biology, 1035 Kirby Drive, 207 Swenson Science Buildling, Duluth, MN, 55812, United States

Keywords:
invasive plants
phenology
Freezing tolerance
Growth.

Presentation Type: Oral Paper
Session: 39, Ecophysiology
Location: 114/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 10:45 AM
Number: 39011
Abstract ID:631
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation