The Stress of Life with Light:: a Graeme Berlyn retrospective
Ellum, David .
Using leaf spectral reflectance to compare rapid acclimation and developmental plasticity in forest understory herbs of southern New England.
The seasonal timing of forest canopy removal can influence the survival of geophytic forest understory herbs adapted to persist in shade. Winter canopy removal allows plants to emerge into a full sun environment and respond to increased light through developmental plasticity. Mature plants respond to summer canopy removal through rapid acclimation of fully developed leaves. Leaf spectral reflectance was used in a common garden experiment to compare developmental plasticity and rapid acclimation of Aralia nudicaulis, Maianthemum canadense and Arisaema triphyllum exposed to full sun at different periods of plant development. Reflectance was measured using a Unispec Spectral Analysis SystemÂ®, reflectance spectrum percent was calculated for wavelengths between 400nm and 1000nm and used to calculate, PRI, Chl NDI and red edge position. For all species, individuals that developed in a full sun environment (plasticity) showed decreased PRI, Chl NDI and red edge position in comparison to control plants. For all species, individuals that were exposed to a full sun environment after developing in the shade (acclimation) showed decreased PRI, Chl NDI and red edge position in comparison to pre-exposure condition. A comparison of the two groups shows similarities in the three reflectance measurements after the acclimation plants were exposed to full sun. Results would indicate that for these species the stress of exposure to full sun is equally compensated for through developmental plasticity and rapid acclimation. However, chlorophyll fluorescence data collected on the same plants indicates significant stress only for the acclimation treatment, meaning that spectral reflectance measurements alone may give be insufficient in comparing plasticity and acclimation in this situation.
Spectral reflectance with a view other measureing techniques demonstrate important physiological properties of understory herbs.
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1 - Warren Wilson College , Enviornmental Studies Dept. , Cpo B 6291, Asheville , NC, 92093
New England Forests.
Presentation Type: Symposium or Colloquium Presentation
Location: 554/Convention Center
Date: Wednesday, August 4th, 2010
Time: 11:00 AM