Type: report

Article abstract: This report presents the results of the 2009 census for the federally endangered and state of California endangered willowy monardella (Monardella viminea) throughout the Marine Corps Air Station (MCAS) Miramar (Station). The purpose of the census is to provide fundamental information on the current condition of the willowy monardella population across the station as a whole. Such information is used in the continued management of willowy monardella on the Station, and to support MCAS Miramar’s stewardship commitments regarding the species population health as well as its management. Through these surveys, the Station’s willowy monardella population was evaluated using an established plant estimation and health assessment protocol, as requested by the Environmental Management Department at MCAS Miramar. The protocol was developed, in part, as a standard approach for approximating individual plants. Given the species’ clumpy appearance and lack of a central stem, it is difficult, if not impossible without creating disturbance and possible damage, for independent observers to differentiate each individual plant consistently. The primary objective of this effort was to identify the current population of willowy monardella at the Station, to recognize patterns of occurrence, and develop a better understanding of the species’ life history to support management efforts. The 2009 census showed that recorded individuals at the Station decreased by approximately 45 percent since the baseline assessment which estimated the population size in 2002. Various explanations for this trend are considered in this report. Possible habitat reasons for this phenomenon include negative effects of drought, fire, and severe flooding, intensified by competition from exotic annual grasses and herbs. While no one of these reasons seems to be the total cause, the combined effects of multiple stresses may be the cause of this decline. However, given the differences in population measurement between survey efforts, recent results are likely somewhat inconclusive in terms of the species’ overall condition. While the majority of plants observed during this survey were in good health, it was apparent that some plants that had been previously recorded were no longer present. Temporary fluctuations in population may be a natural occurrence for this species; however, this concept has yet to be documented. Given the limited information on this species, it is clear that further research would be valuable in understanding the natural history of willowy monardella. This report presents recent findings on the Station’s willowy monardella population and identifies potential management implications. Federal and state laws concerning the treatment of endangered species were followed at all times during the course of this survey effort.