201 
m model for 
HIGH SPECTRAL RESOLUTION REMOTE SENSING OF CANOPY 
CHEMISTRY 
Mary E. Martin and John D. Aber 
ic Laboratory 
>n Aerospace 
0 . 
Complex Systems Research Center 
Morse Hall 
University of New Hampshire 
the Airborne 
irkshop, JPL 
Durham, NH USA 03824 
ABSTRACT 
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ration of the 
: in sensors. 
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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ig ‘89, Reno. 
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. 
the Airborne 
s. California. 
KEY WORDS: Remote sensing, canopy chemistry, nitrogen mineralization, carbon bal 
ance 
algorithm for 
atmospheric 
1 INTRODUCTION 
ransfer code 
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.