PARENT SESSION
Poster Session #59: Fire Ecology II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

The role of fire in controlling the distribution of a rare California summer annual tarplant, Blepharizonia plumosa (Asteraceae).

Carlsen, Tina^*,1, Espeland, Erin², Gregory, Steven¹, ¹ Lawrence Livermore National Laboratory, Livermore, California² University of California, Davis, Davis, California

ABSTRACT- Blepharizonia plumosa is a late-summer flowering tarplant in the California grasslands. Although rare throughout the majority of its range, it is relatively common at Lawrence Livermore National Laboratory Site 300, a high-explosive testing facility. Over 30% of this 2711-ha site is annually burned in the late spring for wildfire control. Areas of annual burns are composed primarily of native perennial grassland, dominated by Poa secunda. Mapping of the Blepharizonia populations shows the plant to be more common in these areas. This is surprising, as at the time of the burns, the species is in a green, vegetative stage of relatively small stature. Therefore, we are collecting data to determine the mechanisms of Blepharizonia persistence in areas undergoing controlled burns. Five years of pre- and post-burn census data from two populations shows high mortality of Blepharizonia when the fire passes directly through the population. However, plants did survive in "micro-patches" that were spared direct contact with flames. Burn timing is also important. When burns are delayed into late spring, the larger plants are able to recover from fire damage. However, the increased fire intensity of burns delayed into early summer results in high plant mortality. Plants surviving the burn typically had a high survival rate to flowering (40 to 60%). Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

KEY WORDS: Blepharizonia plumosa, fire, ecology, persistence