Type: report

Article abstract: Introduction: San Diego ambrosia (Ambrosia pumila) is a sensitive plant species whose northernmost distribution is in southern Riverside County. This perennial herb species was once common in northern Baja California, Mexico but its distribution has been significantly reduced by expansion of agricultural land use. Modern land use within San Diego County has also greatly reduced the historic distribution of San Diego ambrosia. This plant species appears to propagate from a subterranean, rhizome-like root instead of a typical seed-dependant reproduction strategy. If San Diego ambrosia only reproduces vegetatively and is limited in its ability to sexually reproduce, it may not be able to adapt to changing conditions. This may also be partially responsible for the limited distribution of San Diego ambrosia. Monitoring for this plant in Mission Trails Regional Park (MTRP) was conducted on August 15 and August 18, 2003 by Holly Cheong, Melanie Johnson, Betsy Miller, Khalil Martinez, and Eden Nguyen. The largest patch of San Diego ambrosia in MTRP, which is located adjacent to the Kumeyaay Lake Campground, was surveyed. The patch surveyed is identified as patch C6 in the City of San Diego Mission Trails Regional Park San Diego Ambrosia Management Plan (Dudek & Associates, 2000). The goal of the effort was to continue long-term monitoring of San Diego ambrosia under the Multiple Species Conservation Program (MSCP).