Measures of foliar chemical content provide us
with indicators of plant productivity (e.g., levels of
chlorophyll); rate of litter decomposition (e.g., levels
of lignin); and availability of nutrients (e.g.,
nitrogen) in space and time. By making such estimates
remotely we have the potential of studying the quality of the vegetation and a portion of
several nutrient cycles on a local to a global scale.
A number of U.S. organizations and government
agencies have stated that their research goals for
the 1990s include the study of global biogeochemical
cycling, and that remote sensing is a tool
needed to achieve this goal (NASA, 1984; Committee
on Global Change, 1986; NSF, 1987; Earth
System Science Committee, 1988). For example,
the 1990 U.S. agenda for the study of global
change is very specific about the role that remotely
sensed information on foliar chemistry can
play. "New, high spectral resolution remote sensing
techniques show promise of estimating canopy
chemical composition parameters that can be used
to elucidate ecosystem properties. Basic understanding
and wider validation of this approach are
needed" (Committee on Earth Sciences, 1989,
p. 58).