The Stress of Life with Light:: a Graeme Berlyn retrospective
Berlyn, Graeme , Thorhaug, Anitra , Marek, Nancy , Poulos, Helen Mills .
Using Spectral Reflectance for Estimating Leaf Functional Traits and Plant health.
In our laboratory we first studied spectral reflectance of individual leaves using a modified incident light microspectrophotometer in the 1980s (Berlyn et al., 1989). Since that time commercial instruments have become available and the power of the technique and the analysis of the measurements have developed rapidly, especially over the past decade. We also measured leaf functional traits using spectral transmittance and fluorescence of individual leaves (Berlyn et al., 1996), but this technique is yet to be fully exploited, possibly because it is not as easily connected to remote sensing analyses. The power of spectral reflectance is based on two fundamental bases. First is Einstein’s fundamental discovery that light consists of particles, i.e., photons (see Rigden, 2005). The second basis stems from the fact that “light is not really affected by surfaces” (Feynman, 1985). When a photon is incident on a leaf it interacts with electrons throughout the leaf. The photon is scattered and a new photon emitted because electrons can absorb a photon and emit a photon. The consequence is that the “reflected” light has the signature of the pigments in the leaf. If it just struck the surface and bounced off it would not show the characteristic reflectance spectra. These reflectance spectra have a fundamental identity, but the quality and quantity of leaf pigments of a species depends on the physiological state of the leaf and plant. Similarly different species can differ in the types and amounts of leaf pigments and thus the reflectance spectra may be used to characterize plant communities. Spectral reflectance can provide high resolution information on the effect of various stressors such as elevation and latitudinal gradients, acid rain, radiation, gaseous pollutants, salinity, heavy metals, herbivory, and pesticides.
Light , the most fundamental of plant living responses, has been measured by a variety of instruments and for a variety of physical properties. This is a relatively new instrument , which is capable of working in field and laboratory conditions and on the widest variety of plant materials. It has shown excellent applications and has a very great variety of potential future applications, particularly with integrating results with remoting sensing data for large-scale plant community mapping. A variety of types of measurements, their results and implications will be given so the breadth and depth of the types of discoveries which can be made will become apparent as well as the theory behind this type of measurement. The physical theory of both the instrument and the measurement itself will be discussed. The two scientists who have done the most and varied measurements will be giving meta talks about data, anaylsis and implications.
Log in to add this item to your schedule
1 - Yale University, School of Forestry and Environmental Sciences, Greeley Laboratories 375 Prospect St., New Haven, Connecticut, 06901, USA
2 - Yale University School of Forestry & Environmental Studies, 1359 SW 22 TER, Miami, Florida, 33145, USA
3 - Yale University, School of Forestry, 375 Prospect St., New Haven, CT, 06901, usa
4 - Wesleyan University , Environmental Sciences, Shamklin Laboratories 205, Wesleyan Universtiy, Middletown, CT, 06459, usa
Presentation Type: Symposium or Colloquium Presentation
Location: 554/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:15 AM