Exploring the relationship between reflectance red edge and chlorophyll content in slash pine

Abstract

Chlorophyll is a key indicator of the physiological status of a forest canopy. However, its distribution may vary greatly in time and space, so that the estimation of chlorophyll content of canopies or branches by extrapolation from leaf values obtained by destructive sampling is labor intensive and potentially inaccurate. Chlorophyll content is related positively to the point of maximum slope in vegetation reflectance spectra which occurs at wavelengths between 690-740 nm and is known as the "red edge." The red edge of needles on individual slash pine (Pinus elliottii Engelm.) branches and in whole forest canopies was measured with a spectroradiometer. Branches were measured on the ground against a spectrally flat reflectance target and canopies were measured from observation towers against a spectrally variable understory and forest floor. There was a linear relationship between red edge and chlorophyll content of branches (R(2) = 0.91). Measurements of the red edge and this relationship were used to estimate the chlorophyll content of other branches with an error that was lower than that associated with the calorimetric (laboratory) method. There was no relationship between the red edge and the chlorophyll content of whole canopies. This can be explained by the overriding influence of the understory and forest floor, an influence that was illustrated by spectral mixture modeling. The results suggest that the red edge could be used to estimate the chlorophyll content in branches, but it is unlikely to be of value for the estimation of chlorophyll content in canopies unless the canopy cover is high.

Non-destructive determination of maize leaf and canopy chlorophyll content

“…However, either biotic or abiotic factors can induce stress in a plant affecting specific processes on individual leaves resulting i n both a loss of Chi and a change i n its distribution pattern (Barton, 2000). Consequently, methods are required for accurate, non-destructive, and simple estimates of Chl content at canopy scales, rather than for individual leaves (Curran et al, 1990). These methods should improve the accuracy of Chl estimation by taking into account the variability in Chl content within and among leaves in the canopy.…”

An Assesesment of Leaf Chlorophyll Concentration of Afforestation Tree Species in South-Eastern, Nigeria

“…Chlorophyll is a key indicator of the physiological status of forest canopy (Curran et al 1990;Curran et al 1995). However, the chlorophyll content of a forest canopy can be an indicator of such measures of physiological status as photosynthetic capacity, developmental stage, productivity, and stress (Ustin et al 1988;Curran et al 1990;Richardson et al 2002;Khaleghi et al 2012).…”

“…However, the chlorophyll content of a forest canopy can be an indicator of such measures of physiological status as photosynthetic capacity, developmental stage, productivity, and stress (Ustin et al 1988;Curran et al 1990;Richardson et al 2002;Khaleghi et al 2012). Chlorophyll is the green pigment in tree leaves which initiates photosynthesis by absorbing energy from sunlight and transfers this energy to other molecules (Lei et al 1996;Spear 1997;Ekanayake et al 2004).…”

“…According to Curran et al 1990;Curran et al 1995;Filella et al 1995;Richardson et al (2002), these are informed by several factors, first, the amount of solar radiation absorbed by a leaf is largely a function of synthetic pigments, and therefore low concentrations of chlorophyll can directly limit photosynthetic potential and hence primary production. Secondly, much of leaf nitrogen is incorporated in chlorophyll, so quantifying chlorophyll gives an indirect measure of nutrient status in plants (Filella et al 1995;Moran et al 2000).…”

“…Thus, chlorophyll is at the centre of photosynthesis oxidation -reduction reaction between carbon (IV) oxide and water (H 2 O) (Richardson et al 2002;Curran et al 1990;Curran et al 1995). When chlorophyll absorbs light energy the molecules enters into a higher energy state in which it easily gives up an electron to the first available electron-accepting molecules nearby (Flagella et al 1995).…”