Rethinking Chlorophyll Responses To Stress: Fluorescence and Flectance Remote Sensing in a Coastal Environment
ENGINEER RESEARCH AND DEVELOPMENT CENTER ALEXANDRIA VA
Pagination or Media Count:
Chlorophyll fluorescence and hyperspectral reflectance were used to evaluate physiological responses to two common stressors in coastal environments. Chlorophyll content is one indicator of drought and salinity vegetation stress because of its direct role in the photosynthetic process and electron transport. Recent advances in fluorescence spectroscopy have led to the development of numerous reflectance indices that estimate fluorescence emission of vegetation for mapping vegetation stress as chlorophyll content andor carotenoid content changes. Photoprotection via xanthophyll changes and non-photochemical quenching qN have been well correlated to the photochemical reflectance index PRI which has been successfully applied at multiple scales and most commonly associated with drought stress. Our objective was to evaluate chlorophyll responses to drought and salinity induced stress in a common shrub species in laboratory experiments and relate to field collected data. Our results indicate that some species do not breakdown chlorophyll during periods of stress, which may be an adaptive in a highly dynamic environment. Variations in PRI were not related to changes in chlorophyll content or the carotenoidschlorophyll ratio. PRI is an indicator of chronic salinity stress and may be used as an early signal for associated changes due to sea-level rise associated with climate change. Remote sensing of vegetation allows for providing biophysical measurements across landscapes with limited access. However, not all species respond via chlorophyll changes with moderate to high levels of stress and this must be considered as remote sensing of plant signals is applied globally across species.
- Organic Chemistry