Biological Sciences Department
BS in Biological Sciences
Chorro Creek bog thistle (Cirsium fontinale var. obispoense) is a federally endangered variety of Fountain thistle endemic to western San Luis Obispo County. The U.S. Fish and Wildlife Service knows of nineteen populations, many with multiple colonies. A population was discovered in the Reservoir Canyon Natural Reserve in 2001, but has not been monitored or described since the time of its discovery. In fall of 2013, a census of the population was performed, the four colonies were mapped, and a floristic survey was conducted. A field experiment was initiated to determine if reducing the riparian canopy coverage can increase thistle colonization and establishment. Thistles in several populations exhibit close bunching behavior, making some individuals difficult to distinguish. A cluster of closely associated dead thistles in the Laguna Lake population was examined for subsurface connectivity. Physical connectivity of the thistles was observed, but the cause cannot be determined without further analysis.