Dissertation/Thesis Abstract

Photosynthesis and Growth of Invasive Shrubs Across a Light Gradient
by Schack, Brandon, M.S., Southern Illinois University at Edwardsville, 2018, 57; 13420314
Abstract (Summary)

Asiatic honeysuckle (Lonicera mackii) and autumn olive (Elaeagnus umbellata) are two invasive Asiatic shrubs that colonize understories in forests throughout the United States and suppress growth of native species. My research aims to explore the traits of both of these invasive plants in order to better understand the dominance of invasive plant species over native plant species. Both plants’ fruits were collected from Southern Illinois University Edwardsville and, after germination, were randomly transferred to one of five shade enclosures at 20, 40, 60, 80, and 90% light level reduction. After acclimation, plants were analyzed for their photosynthetic capabilities and leaves were harvested and tested for chlorophyll concentration. Dry weights of leaves, shoots, and roots, total leaf count, and stem length were subsequently collected. Light response curves, maximum photosynthetic rate, dark respiration rate, and light compensation point were analyzed for photosynthetic capabilities showing no differences between the two species. Biomass samples showed no difference in allocation potential between species for any plant parts. E. umbellata displayed a large increase in leaf area to total dry mass and specific stem length in the 90% irradiance treatment suggesting an etiolated response to low irradiance. Leaves of L. maackii in the 20% irradiance treatment showed visible signs of photoinhibition followed by a conspicuously large increase to stem RGR, leaf RGR, final leaf count, and longer branch length within the 40% treatment. Both invaders had many traits that were similar, suggesting photosynthetic response to light differs little between the two; however, lower performance of L. maackii in high irradiance and an etiolated response of E. umbellata in low irradiance would suggest that each species has a varying whole plant acclimation potential.

Indexing (document details)
Advisor: Schulz, Kurt
Commitee: Barry, Kelly, Esselman, Elizabeth
School: Southern Illinois University at Edwardsville
Department: Biological Sciences
School Location: United States -- Illinois
Source: MAI 58/04M(E), Masters Abstracts International
Subjects: Botany
Publication Number: 13420314
ISBN: 978-0-438-81934-4
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