Field Studies of Ceanothus leucodermis Chaparral Burned Sites in California

Populations of the chaparral shrub were sampled in southern California and further north in Monterey and Santa Clara counties and it was discovered that postfire regeneration modes were different. The southern California populations had substantial resprouting with some seedling recruitment. The Monterey populations had no resprouting ability and recovery was entirely by seedlings. However, there is an age effect in that when young these northern California populations fail to recruit seedlings due to lack of a seed bank buildup in the short interval since the last fire. These populations likely will be extirpated. I hypothesize that this obligate seeding mode has been selected for because seed reproduction is more reliable when intervals between fires are very long, longer that resprouting shrubs would survive. Support for this is provided by demonstrating substantially higher lightning fire frequencies in southern California than in the Monterey and Santa Clara area.