Browsing by Subject "plant hydraulics"

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    Ecological and physiological implications of vascular structure and function in oaks
    (2019-12) Teshera-Levye, Jennifer
    A plant's ability to transport water is one of its most critical physiological functions. Indeed, plant vasculature has been described as the ”backbone” supporting the productivity of terrestrial ecosystems. In my dissertation research I have investigated connections between plant hydraulics and ecological function at at two scales: first, the role that whole-plant water movement plays in how three oak species partition a hydrologic gradient, and second, the ways leaf level vascular structure can offer insights into overall plant function when studied through a framework informed by network theory. I will discuss results from a study testing how differences in water-use traits might permit three oak species to co-exist in a small geographic area, where we have shown that whole-plant hydraulic conductance is one of several characteristics that explains their local distribution. I will then introduce "LeafGrapher," a software tool I have developed to apply a network analysis approach to leaf venation architecture. Finally I demonstrate the validity of these metrics by looking at the relationships between these network-derived venation traits and known plant functional traits measured on North American and European oaks in a common garden. This work gives us some novel insights into the role plant vascular biology plays in a broader eco-physiological framework.
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    Investigation of vascular limitations on floral water loss in temperate woody species
    (2018-12) McMann, Natalie
    In temperate biomes, limitations imposed by vascular physiology may influence floral water use in woody species. Freeze-thaw induced embolism in the xylem can reduce vascular transport capacity in the early spring, potentially limiting growth. To investigate whether xylem transport capacity impacts floral physiology, I quantified inflorescence water loss rates and stem hydraulic conductivity of five woody species that flower before producing leaves. I found inflorescence size and ambient temperature at flowering positively correlated with water loss. However, I detected no correlation between branch level floral water loss and stem hydraulic conductivity within species. Furthermore, a comparison of branch level water loss rates from inflorescences and leaves showed that leaf water loss is 2–4 orders of magnitude greater than that of flowers. To evaluate whether flowers were primarily phloem or xylem hydrated, I modeled the amount of water brought in during floral development and full bloom. Despite their relatively low rates of water loss, the model indicates that flowers in this study obtain the majority of their water from the xylem. Overall, the data suggest that within species floral water loss may not be limited by the xylem during flowering, but large differences in floral water loss and stem conductivity among species could explain hydraulic trait variation between large and small flowered plants.