Merritt, Benjamin , Jones, Josh , Culley, Theresa .
Ecophysiological traits of the Callery Pear (Pyrus calleryana) and their potential to facilitate invasive spread .
The impacts of invasive species on natural ecosystems and the manner in which these organisms become invasive if of great interest to scientists and land managers alike. As only a small number of introduced plant species actually invade non-native regions, their morphological and ecological characteristics are often examined to understand what specific traits facilitate aggressive invasions. The Callery Pear (Pyrus calleryana) provides an opportunity to observe less well-studied traits, such as those relating to ecophysiology. As a popular ornamental tree frequently sold throughout the United States, the Asian P. calleryana has spread within its introduced range through hybridization between different commercially-produced cultivars. We examined the photosynthetic rate, transpiration, and water use efficiency (WUE) within two different generations of this species grown under differing levels of stress over time. Individuals were grown from seed of known cultivars (F1 or 'early generation hybrids') or from wild individuals ('advanced generation hybrids'). All ecophysiological traits were measured under various sampling conditions during a four year period: initially when seedlings were six months old, three-old saplings that were severely root-bound with no fertilization, and those same saplings that were subsequently transplanted into larger pots, followed later by water and nutrient stress. In general, ecophysiology differed significantly between the early and advanced generation hybrids, but the direction and magnitude of significance varied with sampling period. Advanced generation hybrids exhibited greater photosynthetic and transpiration rates in three of the four sampling periods, with the root-bound samples displaying the largest significant difference. In contrast, WUE was lower in the late generation hybrids across all four sampling periods, with significant differences detected in the initial and root-bound sampling periods. Although P. calleryana exhibited moderate levels of photosynthetic rates, transpiration, and WUE, invasive spread in this species may be influenced to a greater extent by other traits such as abundant seed production, early maturation time, and greater leaf retention. Consequently, a single factor may not be the sole source of invasiveness in this species, emphasizing that a more comprehensive approach focusing on a variety of traits, including ecophysiology, may be needed to understand the mechanisms underlying spread in invasive species.
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1 - University of Cincinnati, Biological Sciences, 614 Rieveschl Hall, Cincinnati, OH, 45221-0006, USA
2 - University Of Cincinnati, Department Of Biological Sciences, 614 Rieveschl Hall, Cincinnati, OH, 45221-0006, USA
Presentation Type: Poster:Posters for Sections
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM