Ramp, Jennifer M. .
Pollination and seed set of the endangered vernal pool annual Lasthenia conjugens (Asteraceae).
California’s vernal pools are a highly endangered ecosystem threatened by habitat loss. The vernal pools are home to more than 60 endemic plant species as well as dozens of invertebrates. Many vernal pool plants are self-incompatible, relying on pollinators for seed set. Due to their nature, vernal pools have a patchy distribution within a grassland matrix making gene flow between pools rare and usually mediated by pollinators and seed dispersers. The vernal pool annual Lasthenia conjugens (Asteraceae) is self-incompatible and members of the bee genus Andrenidae are known to be oligolectic on flowers of Lasthenia. At Travis Air Force Base, in Fairfield, California, a restoration project is underway with restored and natural vernal pools. Restored pools were seeded with 1-5 native plant species in 2000 and 2001. Andrenid pollinators are present in the natural pools at Travis. As a means of assessing pool sustainability, pollinator observations were conducted in natural and restored vernal pools at Travis in the spring of 2002 and 2003. Andrenid pollinators were rare in all pools observed and were recorded only once per year in a restored pool. Restored pools had considerably fewer visitors to L. conjugens than the natural pools with the most common visitors being members of the genus Sciaridae. Members of Empididae and Bombyliidae were also present in low numbers within both pool types. There was not a difference in seed set between the two pool types despite the difference in visitation rates. This indicates that the Sciarid visitors may be efficient pollinators of L. conjugens. To examine pollen limitation in the field, hand supplements were performed in 2002 and 2003 of both restored and natural pool individuals. There was no difference in seed set between supplemented and non-supplemented individuals indicating L. conjugens is not pollen limited in the field.
1 - University of Colorado, Department of Ecology and Evolutionary Biology, UCB 334, Boulder, Colorado, 80309-0334, USA
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 3:30 PM