Fog water use in coastal California shrublands

Background/Question/Methods

Fog can be a significant force in shaping plant communities, particularly in coastal regions such as in California where it ameliorates summer temperatures and can reduce drought stress. The effect of fog on coastal shrublands, particularly fire prone ones, has not been well studied and the likelihood that fog events may change in the future supports the need for research into the impact of fog on vegetation structure and functioning. This research is particularly vital given the ecological and socioeconomic importance of fire in these semi-arid ecosystems. This study involved extensive sampling of Hydrogen and Oxygen isotopes in water from fog, rain, groundwater and plant stems to determine proportional fog water use in several shrub species in Santa Barbara County, CA. We sampled water and shrubs at field sites along the coast and in the interior throughout the summers of 2011 and 2012.

Results/Conclusions

We determined that rain, groundwater and fog along the coast have different isotopic signatures which allows for the determination of fog use for both chaparral and coastal sage scrub shrub species. From isotope analysis of extracted plant water samples, it appears that some shrub species are using fog water in the late summer. To understand the context and importance of this novel water use, it is important to determine how it relates to changes in plant water content, live fuel moisture and patterns of fire disturbance in these ecosystems.