Abstract:
The optical reflectance spectra of living vegetation are controlled by the detailed chemistry and physics of the leaves and other parts of the plant. Modern hyperspectral sensors can measure the reflectance over wide areas allowing regional and worldwide monitoring of vegetation status. For example, satellite images record the spring 'greening' of eastern North America. The work described in this paper seeks to measure how leaf reflectance changes with season, species, and location. A pilot project in 2007 established the laboratory procedures for measuring leaf reflectance, but was limited to three trees at Hanscom AFB, Massachusetts. A very limited data set was collected in 2008 due to use of the field spectrometer for other projects. The attached 2008 SPIE paper describes the 2007 measurements and field and laboratory procedures.
The research goal for 2009 is to extend the leaf reflectance measurements to multiple sites in eastern Massachusetts, beginning at leaf-out in early Spring and continuing to Autumn (potential sites: Hanscom AFB; Drumlin Farm, Lincoln; Acton Arboretum; Harvard Forest). We want to establish the geographical and temporal variability of commonly used remote sensing measures of vegetation status. One such quantity, the red edge inflection point, is controlled by the chlorophyll content of the leaf, and has been found to be an indicator of plant stress such as drought and water contamination. A particular interest is to try to use optical spectra to distinguish wetland and upland species.
We welcome collaboration with other investigators. On one hand, if you know of a site that will allow leaf sampling (approximately 10-15 leaves per measurement), we would like to extend the geographic range of our experiment. In addition, we would be most interested in knowing of any biochemical measurements that could be related to leaf reflectance. Examples are leaf water and chlorophyll content.
