What Baja California can teach us about the value of fog to plants.

with Sula Vanderplank
Monday, June 21, 2021 

Fog is common in coasts with sunny days and upwelling cold water. Fogs also tend to show a strong gradient from coast to inland. In Mediterranean climate vegetation, the primary control of plant phenology (flowering, fruiting, and senescence) is moisture, including fog moisture, making distance from the coast significant for the timing of flowering, as well as in plant distribution patterns in general. Fog studies in arid lands, such as the Baja California peninsula, elucidate the role that fog plays in plant survival and behavior.

Flowering times and the synchrony of flowering can be significantly shifted, which in turn affects predation and the timing of seed release, along with seedling recruitment and survival, an important factor for restoration and management efforts. Up the trophic chain, animals also respond to the presence of coastal fogs through shifts in communication, breeding, and behavior based on plant response. Perhaps most significantly, the presence of consistent fogs results in the creation of climate refugia that have reduced temperature extremes and protect species from extinction during long-term climatic change. 

On the Baja California peninsula, the influence of Pacific moisture can be seen in the distribution of different ecoregions at the largest scale, including the great fog deserts in the center of the peninsula. At a smaller scale, the southernmost extent of the California Floristic Province is a biological diversity hotspot of high endemism and conservation value, with two steep moisture gradients: rainfall (N-S), and coastal fogs (W-E).

Species that are fog adapted in Baja California may be excellent choices for Bay Area gardens now, and even more so in the not too distant future. Our foggy coasts should be particular priorities for species conservation and will likely allow the most diverse gardens in a changing climate.

Sula is the Director of Terrestrial Ecosystem Conservation for Pronatura Noroeste, Baja California, Mexico. A botanist by training, she has studied the diverse ecosystems of Baja California and the offshore islands for the last 15 years, and has a Ph.D. in Plant Ecology from UC Riverside. Sula serves as adjunct Faculty at San Diego State University and the Center for Scientific Research and Higher Learning (CICESE) in Ensenada. She maintains an active cross-border research program focused on coastal ecosystems, and has published more than 50 scholarly articles and books. She is currently working with the San Diego Natural History Museum and San Diego Zoo Global to evaluate the status of cross-border rare plants. 

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