Document: BRI-3-89-10

Functional type classification of southern Califonian vegetation using spectral reflectance.

ZUTTA, B.R*, D.SIMS and J.AGAMON

California State University of Los Angeles, Los Angeles, CA 90032 USA ¹

Abstract:
Southern Californian vegetation, exposed to strong seasonal weather cycles and dynamic disturbance regimes, undergo wide variations in photosynthetic fluxes and other ecosystem processes. Sorting vegetation by "functional types," based on their resource use patterns and seasonal response, provides one simplification to help understand changing ecosystem fluxes in these systems. For this approach to be broadly applicable, these functional types must be detectable through remote sensing. Our objective was to measure the seasonal change in spectral reflectance of Southern Californian vegetation and to use the seasonal and spectral variability to categorize species into optically distinct types. A field spectrometer was used to measure reflectance at 1-meter intervals along 100 meter transects in a variety of vegetation types, located in the Santa Monica Mountains of Southern California. Several spectral indices were used in principal components analysis to characterize the variability in spectral reflectance in time and space. Initial results of this study indicate limited power to separate functional groups (e.g. associated with contrasting phenology or photosynthetic rates) when spectra from a single date were used. The ability to separate optical types was enhanced when multiple sampling dates were included in the analysis. Further work is focusing on the physiological characteristics of the optically determined functional groups. Development of this approach may lead to better characterization of functional types and an understanding of the impacts of disturbance and global change on ecosystem processes.

Keywords: Remote sensing, functional types, ecosystem function

This abstract is being presented at: 10:30 AM in session:
REMOTE SENSING