Graduate Thesis Or Dissertation
 

Photosynthesis of conifers : influential factors and potentials for remote sensing

Público Deposited

Contenido Descargable

Descargar PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/x346d8819

Descriptions

Attribute NameValues
Creator
Abstract
  • Remote sensing offers the potential for monitoring photosynthesis over large temporal and spatial scales. The purpose of this thesis is to provide information that will help to develop methods to predict photosynthesis from the light reflected by canopies. The studies focused on a simple model of canopy photosynthetic potential: Acanopy = E APAR, where Acanopy is photosynthetic potential, APAR is the fraction of incident visible light that can be absorbed by the canopy, and is the light use efficiency. The first experiment showed that for small canopies of Douglas-fir seedlings, E was not a constant, even though environmental conditions were the same for all measurements of photosynthesis. APAR alone explained 36% of the variability in canopy photosynthesis. Photosynthetic capacity of needles from the top of a canopy was a good indicator of E: A model combining APAR and photosynthetic capacity explained 83% of the variation in canopy photosynthesis. Chlorophyll concentration was positively correlated with photosynthetic capacity, but had no measurable correlation with APAR. Leaf area alone explained most of the variation in APAR (R2 = 0.87). The second study demonstrated that the normalized difference vegetation index (NDVI), derived from amounts of red and near infrared light reflected by a vegetation, was a better indicator of E APAR than of APAR alone. This was because changes in leaf area at constant chlorophyll concentration caused reflectance to change in the near infrared but not the visible region. NDVI, however, was sensitive to both near infrared and visible reflectance. When chlorophyll varied at constant leaf area, NDVI varied but APAR did not. Because of the relationship between chlorophyll and photosynthetic capacity, and because variation in chlorophyll caused changes in the reflectance of red light, NDVI incorporated information about E. The third study demonstrated that in a mature hemlock stand, photosynthetic capacity did not change through the course of a year, despite below-freezing temperatures on two sampling dates, or in response to increased leaf nitrogen after fertilization. Previous studies have shown that many conifers have reduced photosynthetic capacity during the winter, and that photosynthetic capacity is often related to leaf nitrogen. This study points out exceptions that need to be considered in models of whole canopy photosynthesis.
Resource Type
Fecha Disponible
Fecha de Emisión
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Declaración de derechos
Publisher
Peer Reviewed
Language
Digitization Specifications
  • PDF derivative scanned at 300 ppi (256 B&W), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces

Relaciones

Parents:

This work has no parents.

En Collection:

Elementos

Miniatura Título Fecha de subida Visibilidad Acciones
file details Yoder_Barbara_J_1992.pdf 2017-10-20 Público Descargar