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HIGH SPECTRAL RESOLUTION REMOTE SENSING OF CANOPY
CHEMISTRY
Mary E. Martin and John D. Aber
ic Laboratory
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Complex Systems Research Center
Morse Hall
University of New Hampshire
the Airborne
irkshop, JPL
Durham, NH USA 03824
ABSTRACT
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Foliar concentrations of nitrogen and lignin are closely related to the ecosystem processes
of litter decomposition and photosynthesis. Large scale assessments of nutrient cycling
and carbon balance in forested ecosystems are important to our understanding of the role
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of forests in global nutrient and energy cycles. Field measurements of these processes have
been made for only a limited number of sites due to the time and expense involved in data
collection and analysis. In this work, we use high spectral resolution remote sensing data
from the Airborne Visible/Infrared Imaging Spectrometer to measure canopy nitrogen
over. 1990a.
ared Imaging
Spectrometer
and lignin over large areas at Harvard Forest, MA and Blackhawk Island, WI. These
measurements are then used with existing models to make spatial estimates of nitrogen
mineralization and carbon balance.
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s. California.
KEY WORDS: Remote sensing, canopy chemistry, nitrogen mineralization, carbon bal
ance
algorithm for
atmospheric
1 INTRODUCTION
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Development of laboratory instruments and procedures over the last twenty years has
resulted in the identification of specific regions of the NIR spectrum which may be used
for determining nitrogen and lignin concentrations in plant materials [1, 2]. In recent
years, similar high spectral resolution visible and infrared data have been available via
Y.O Gallery,
MA.
airborne remote sensing instruments. Using data from NASA’s Airborne Visible/Infrared
Imaging Spectrometer (AVIRIS) we attempt to identify spectral regions correlated with
foliar chemistry at the canopy level in temperate forests.
Two well-studied research sites were used for this study. Harvard Forest is a 1200 hectare
research site in central Massachusetts, USA (Latitude 42°32’N Longitude 72°11’W) con
taining a combination of natural hardwood and mixed hardwood/conifer stands as well
as several plantations of pine, spruce and larch which exhibit a wide range of nitrogen
and lignin concentration. Blackhawk Island in south-central Wisconsin, USA (Latitude
43°40’N Longitude 89°45’W), is a natural area containing a very wide diversity of forest
types including maple, oak, pine and hemlock.
