Foliar water uptake of fog confers ecophysiological benefits to four common tree species of southeastern freshwater forested wetlands

Abstract

AbstractFog, dew and cloud‐borne mist are sources of water to vegetation in many ecosystems. The importance of fog as a water source has been documented well beyond ecosystems where plants experience fog for extensive periods over the course of the day (e.g. cloud forests); however, relatively little is known regarding the roles of fog and foliar water uptake in ecosystems such as coastal freshwater wetlands that do not experience fog for extensive periods over the course of the day. Coastal freshwater wetland ecosystems lie on the forefront of climate change‐associated stressors that threaten freshwater supplies to vegetation. Considering the potential impact of climate warming on diminishing coastal fog regimes, an improved understanding of the ecophysiological benefits of fog immersion to the vegetation in these ecosystems is critical for understanding the response of these ecosystems to global climate change. Herein, we investigate the potential for foliar water deposition from fog to act as a direct freshwater subsidy to four tree species (Taxodium distichum (L.) Rich., Nyssa aquatica L., Nyssa biflora Walter and Liquidambar styraciflua L.) that are common in coastal freshwater wetlands. All four species showed the capacity for foliar water uptake across the leaf/needle surface, with a ca. 5–10% increase in leaf water content after a 3‐h submersion experiment. Stable isotopes of water provided strong evidence for foliar water uptake in all four species and for bark water uptake in T. distichum after a 24‐h fogging experiment. Fog exposure also resulted in several ecophysiological benefits to the saplings, including significant improvements in pre‐dawn water status and net photosynthesis.