Red and Photographic Infrared Linear Combinations for Monitoring Vegetation

Red and Photographic Infrared Linear Combinations for Monitoring Vegetation

MAY 1978 | Compton J. Tucker
This document, titled "Red and Photographic Infrared Linear Combinations for Monitoring Vegetation," by Compton J. Tucker, evaluates the effectiveness of various linear combinations of red and photographic infrared (IR) radiances in monitoring vegetation biomass and physiological status. The study uses in situ collected spectrometer data from three sampling periods—June, September, and October 1972—to analyze the relationships between these linear combinations and canopy variables such as total wet biomass, leaf water content, and chlorophyll content. The analysis includes regression models for both green and red linear combinations, as well as IR and red linear combinations. The results show that IR and red linear combinations are more significant in regression analyses compared to green and red combinations, with the IR-red difference, vegetation index (VI), transformed vegetation index (TVI), and square root of the IR/red ratio being the most significant. These combinations are particularly sensitive to photosynthetically active biomass or green leaf area. The study also examines the influence of different IR bandwidths on the regression significance for the June data, finding no significant differences among the three bandwidths (0.75-0.80 μm, 0.80-0.90 μm, and 0.75-0.90 μm). Additionally, the phenological considerations are discussed, highlighting the gradual accumulation of standing vegetation from June to October, with the October data representing entirely standing dead vegetation. The conclusions emphasize the utility of IR and red linear combinations in monitoring vegetation, particularly for assessing photosynthetically active biomass.This document, titled "Red and Photographic Infrared Linear Combinations for Monitoring Vegetation," by Compton J. Tucker, evaluates the effectiveness of various linear combinations of red and photographic infrared (IR) radiances in monitoring vegetation biomass and physiological status. The study uses in situ collected spectrometer data from three sampling periods—June, September, and October 1972—to analyze the relationships between these linear combinations and canopy variables such as total wet biomass, leaf water content, and chlorophyll content. The analysis includes regression models for both green and red linear combinations, as well as IR and red linear combinations. The results show that IR and red linear combinations are more significant in regression analyses compared to green and red combinations, with the IR-red difference, vegetation index (VI), transformed vegetation index (TVI), and square root of the IR/red ratio being the most significant. These combinations are particularly sensitive to photosynthetically active biomass or green leaf area. The study also examines the influence of different IR bandwidths on the regression significance for the June data, finding no significant differences among the three bandwidths (0.75-0.80 μm, 0.80-0.90 μm, and 0.75-0.90 μm). Additionally, the phenological considerations are discussed, highlighting the gradual accumulation of standing vegetation from June to October, with the October data representing entirely standing dead vegetation. The conclusions emphasize the utility of IR and red linear combinations in monitoring vegetation, particularly for assessing photosynthetically active biomass.
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