Abstract
The total solar eclipse of August 21, 2017 created a path of totality ~115 km in width across the United States. While eclipse observations have shown distinct responses in animal behavior often emulating nocturnal behavior, the influence of eclipses on plant physiology are less understood. We investigated physiological perturbations due to rapid changes of sunlight and air temperature in big sagebrush (Artemisia tridentata ssp. vaseyana), a desert shrub common within the path of eclipse totality. Leaf gas exchange, water potential, and chlorophyll a fluorescence were monitored during the eclipse and compared to responses obtained the day before in absence of the eclipse. On the day of the eclipse, air temperature decreased by 6.4 °C, coupled with a 1.0 kPa drop in vapor pressure deficit having a 9-minute lag following totality. Using chlorophyll a fluorescence measurements, we found photosynthetic efficiency of photosystem II (Fv’/Fm’) recovered to near dark acclimated state (i.e., 87%), but the short duration of darkness did not allow for complete recovery. Gas exchange data and a simple light response model were used to estimate a 14% reduction in carbon assimilation for one day over sagebrush dominated areas within the path of totality for the Western United States.
Highlights
The total solar eclipse of August 21, 2017 was one of the most anticipated astrological phenomena to date, inspiring over 150 million of people from all over the world to observe the rare event[1]
Plants cope with decreasing temperatures, changes in vapor pressure deficit (VPD), and more or less sudden variations of incoming radiation on a daily basis
Photosynthesis and transpiration are synced to the time of the day by the presence of an endogenous clock that responds to environmental cues including fluctuations of light[16,17]
Summary
The total solar eclipse of August 21, 2017 was one of the most anticipated astrological phenomena to date, inspiring over 150 million of people from all over the world to observe the rare event[1]. Plants cope with decreasing temperatures, changes in vapor pressure deficit (VPD), and more or less sudden variations of incoming radiation on a daily basis These factors are considered primary drivers of photosynthesis and transpiration[10] and their fluctuations have been shown to largely influence photochemical activity and evaporative demand[11,12,13,14,15]. Big sagebrush ecosystems support a regionally high species diversity and they represent key contributions to local biogeochemical cycles, with the majority of stored carbon sequestered in above- and belowground woody biomass and soil organic matter[26,27] These distinct communities are characterized by physiological adaptations to semi-arid environments, including hydraulic redistribution of deep ground water reserves and canopy architecture allowing for maximal water-use efficiency[13,28,29,30]. Hydraulic and photosynthetic mechanisms may require minutes to hours to recover to pre-stress levels with the limits of photoprotective mechanisms and significance of photoinhibition still under investigation[40,41,42,43]
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