El Niño Impacts on Vernal Pool Flora in Jaramillo, Baja California

The Jaramillo Vernal Pools, located on the coastal mesas south of Colonet in northwestern Baja California, host one of the region’s most distinctive seasonal plant communities. These temporary wetlands fill with water after winter and spring rains, creating short-lived habitats where specialized plants complete their entire life cycle in just a few weeks. During strong El Niño years, rainfall increases dramatically, activating pools that remain dry in typical seasons and occasionally connecting adjacent pools. These changes can alter germination patterns, shift species distributions, and influence how rare and endemic plants occupy the landscape.

This project documents how El Niño–driven rainfall patterns shape the emergence, and diversity of vernal pool flora in Jaramillo. The monitoring is conducted once per year, timed to coincide with peak activation when ephemeral species are most identifiable. During each annual visit, we collect georeferenced photo documentation, GPS-based spatial data, and systematic floristic observations that document the peak seasonal expression of each pool. This approach allows year-to-year comparisons of pool activation, floristic composition, and the response of sensitive species to climatic variability.

By combining botanical observations with rainfall and soil moisture data, the project will clarify how extreme climate events influence one of the most unique ephemeral floras in the California Floristic Province. The findings will support regional conservation planning, improve understanding of climate-sensitive plant communities, and strengthen cross-border ecological collaboration.

This work is led by Mariana Delgado in collaboration with regional botanists and academic partners, contributing essential baseline information for long-term ecological monitoring in the Jaramillo landscape.