Flowering phenology indicates plant flammability in a dominant shrub species

Changes in plant phenology provide vital information on climatic shifts, species interactions, and ecological processes. By quantifying plant phenology, we reveal patterns of how plants are integrating environmental conditions and we use this information to inform conservation, policy, and management. In wildfire-prone regions of the world and especially California, a critical ecological process and management issue is wildfire disturbance. To gauge wildfire risk in these regions, scientists and managers monitor live fuel moisture (LFM), a proxy for plant flammability. We investigated the relationship between plant phenology and LFM for the widespread shrub species Adenostoma fasciculatum from two counties in Southern California over 6 years and analyzed the data in the context of LFM thresholds of wildfire risk. We found a correlation between transitions in reproductive phenology and LFM for A. fasciculatum. We also correlated reproductive phenology from the National Phenology Network with nearby LFM measurements from the National Fuel Moisture Database and found a similar relationship that spans the state of California. With simple observations of reproductive phenology, on-the-ground measurements of a dominant shrub species allow for rapid assessment of plant flammability with the potential for large spatial coverage. This study reveals how plant phenological patterns can inform us about ecological processes and potentially contribute to management decisions.