Nine years of monitoring the rare annual clay lens obligate San Diego thornmint, Acanthomintha ilicifolia
Nine years of monitoring the rare annual clay lens obligate San Diego thornmint, Acanthomintha ilicifolia (Lamiaceae): General relationships and possible drivers of abundance
Patrick McConnell, Markus Spiegelberg; email@example.com
Center for Natural Lands Management
San Diego thornmint is a federal and state listed (FT, CE) endemic to San Diego County and Baja California. The species exhibits strong annual variation in population counts throughout its range, and is known from only 68 occurrences. The Center for Natural Lands Management manages and monitors occurrences in Carlsbad California. The most important driver of population abundance is winter rainfall. However, winter temperatures also appear to have an influence on thornmint abundance. The largest annual population counts have coincided with the warmest winter months, which accumulated the highest rainfall. These seasons appeared to have slightly warmer rainfall event temperatures than the other six years. Fall rainfall appears less influential than winter rainfall in predicting population counts. Intermediate counts have been observed during a dry year, indicating that one rainfall event is enough to provide for germination and maturation.