Meeting Abstract

67.8  Wednesday, Jan. 6  Population Density effects on Pollinator Service of the Endangered Plant Lyon’s Pentachaeta (Pentachaeta lyonii) HOLT, J.R.*; WILSON, P.S.; BRIGHAM, C.; California State University, Northridge holtjocelyn@gmail.com

There are over 2300 endemic plant species in California. As California’s population grows habitat fragmentation will continue to threaten endemics with extirpation or extinction. Lyon’s Pentachaeta is a federally endangered sunflower that serves as a food source for generalist pollinators. This endemic plant requires obligate out-crossing and is at risk of extirpation. Understanding if low density patches of Lyon’s Pentachaeta experience the Allee effect, the inability to attract mates at low densities, may reduce this risk of extirpation through management plans. In 2008, pollinator observations were conducted on individuals in natural patches. In 2009, potted plants were placed in field to measure the quality of pollinator service varying distances away from patches. This was done to determine how the quality of pollination service depends on the density Lyon’s Pentachaeta. In 2008, seed set did not vary with density implying that less dense patches did not experience the Allee effect. I predict in 2009 there will be no significant difference in seed set between individuals in patches versus those varying distances from a patch. If true, this would suggest that low density patches are not at risk of extirpation due to pollinator limitation and that some other factor is causing population declines and eventual disappearance. Other factors contributing to extirpation and population declines could include competition with non-native plants, habitat loss, or decreased seed dispersal. Understanding the pollination ecology of Lyon’s Pentachaeta will direct future management and research for this endangered plant of the Coastal Sage Scrub Community.