Remote detection of air pollution stress to vegetation - Laboratory-level studiesAn experimental investigation of the role of leaf chemistry, anatomy, moisture content, and canopy density on spectral reflectance in healthy and pollution stressed western conifer needles and broad-leafed species of California coastal sage scrub is presented. Acid mist at a level of pH 2.0 is found to more severely effect chlorophyll loss and leaf death than ozone at a level of 0.2 ppm for a four-week period. Both pollutants cause water loss, affecting Bands 4 and 5 in nonlinear ways. The infrared bands initially rise as free water is lost, and subsequently, scattering and reflectance decline. The net effect is shown to be a reduction in TM 4/3 and a rise in TM 5/4 with pollution stress. Under more severe pollution stresses, the decline of leaf area indices due to accelerated leaf drop accentuates the expected TM 4/3 and TM 5/4 changes.
Westman, Walter E. (NASA Ames Research Center Moffett Field, CA, United States)
Price, Curtis V. (NASA Ames Research Center Moffett Field, CA, United States)
August 13, 2013
January 1, 1987
Earth Resources And Remote Sensing
CONTRACT_GRANT: NASA TASK 199-30-72-05 CONTRACT_GRANT: NASA TASK 677-21-35-08