COMPARISON OF BROAD-BAND AND NARROW-BAND RED AND NEAR-INFRARED VEGETATION INDEXES

An experiment has been conducted in which narrow-band field reflectanc e spectra were acquired of a roofed pinyon pine canopy with Fee differ ent gravel backgrounds. Leaf area teas successively removed as the mea surements were repeated. From these reflectance spectra, narrow-band a nd broad-band (AVHRR, TM, MSS) red and near-infrared (NIR) vegetation index values were calculated. The performance of the vegetation indice s was evaluated based on their capability to accurately estimate leaf area index (LAI) and percent green cover. Background effects were foun d for each of the tested vegetation indices. However the background ef fects are most pronounced in the normalized difference vegetation inde x (NDVI) and ratio vegetation index (RVI). Background effects can be r educed using either the perpendicular vegetation index (PVI) or soil a djusted vegetation index (SAVI) formulations. The narrow-band versions of these vegetation indices had only slightly better accuracy than th eir broad-band counterparts. The background effects were minimized usi ng derivative based vegetation indices, which measure the amplitude of the chlorophyll red-edge using continuous narrow-band spectra from 62 6 nm to 795 nm.