Foliar uptake of fog in coastal California shrub species
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Understanding plant water uptake is important in ecosystems that experience periodic drought. In many Mediterranean-type climates like coastal California, plants are subject to significant drought and wildfire disturbance. During the dry summer months, coastal shrub species are often exposed to leaf wetting from overnight fog events. This study sought to determine whether foliar uptake of fog occurs in shrub species and how this uptake affects physiology and fuel condition. In a controlled greenhouse experiment, dominant California shrub species were exposed to isotopically labeled fog water and plant responses were measured. Potted plants were covered at the base to prevent root uptake. The deuterium label was detected in the leaves of four out of five species and in the stems of two of the species. While there was a minimal effect of foliar water uptake on live fuel moisture, several species had lower xylem tension and greater photosynthetic rates after overnight fog treatments, especially Salvia leucophylla. Coastal fog may provide a moisture source for many species during the summer drought, but the utilization of this water source may vary based on foliar morphology, phenology and plant water balance. From this study, it appears that drought-deciduous species (Artemisia californica and Salvia leucophylla) benefit more from overnight fog events than evergreen species (Adenostoma fasciculatum, Baccharis pilularis and Ceanothus megacarpus). This differential response to fog exposure among California shrub species may affect species distributions and physiological tolerances under future climate scenarios.
KeywordsFoliar water uptake Fog Stable isotopes Shrubs California Live fuel moisture
Many thanks to Dr. Carla D’Antonio and the UCSB Greenhouse for logistical and financial support, Dr. Carla D’Antonio, Dr. Max Moritz, Dr. Chris Still and Dr. Dar Roberts for helpful comments on an earlier version of this manuscript, and Dr. Todd Dawson, Dr. Stefania Mambelli and the Center for Stable Isotope Biogeochemistry at UC Berkeley for guidance and facilities. This project was funded by National Science Foundation Doctoral Dissertation Improvement Grant Award #1311605 and supported by the Isotope Inter-University Training for Continental-scale Ecology Fellowship, University of Utah.
Author contribution statement
NCE conceived, designed, and executed this study and wrote the manuscript. No other person is entitled to authorship.
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