Rethinking Chlorophyll Responses to Stress: Fluorescence and Reflectance Remote Sensing in a Coastal Environment

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 and/or 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 carotenoids/chlorophyll 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. Conference Name: 4th INTERNATIONAL WORKSHOP ON REMOTE SENSING OF VEGETATION FLUORESCENCE, VAL Conference Date: November 15, 2010 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 and/or 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 carotenoids/chlorophyll 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. RETHINKING CHLOROPHYLL RESPONSES TO STRESS: FLUORESCENCE AND REFLECTANCE REMOTE SENSING IN A COASTAL ENVIRONMENT Julie C Zinnert (Naumann), Jean D Nelson, Jaclyn K Vick, Ava M Hoffman, Donald R Young (1) US Army Corps of Engineers ERDC 7701 Telegraph Road Alexandria, Virginia USA, [email protected] (2) Virginia Commonwealth University, Department of Biology, 1000 West Cary Street Richmond, Virginia USA