PARENT SESSION
Oral Session #27: Fire Ecology.
Presiding: C. Allen
Tuesday, August 6. 8:00 AM to 11:30 AM. Graham Meeting Room, TCC.

Seed bank variation in Mojave desertscrub relative to wildfire, granivores and invasive species.

Esque, Todd^*,1,2, Tracy, C. Richard², ¹ USGS, Las Vegas Field Station, Las Vegas, NV² University of Nevada, Biological Resources Research Center, Reno, NV

ABSTRACT- Persistent seed banks represent the current and future potential of annual plant populations in the Mojave Desert. Fluctuations in plant populations are reflected in the seed bank, particularly when severe disturbances occur. In this experiment we manipulated the presence and absence of granivorous ants and rodents, and fire to understand mechanisms of changes in Mojave desertscrub annual plant populations particularly with respect to the alien annual grasses: Bromus madritensis ssp. rubens and Schismus spp. Experimental data are compared to seed bank dynamics across landscapes. When averaged across microsites annual plant species richness was significantly different between burn treatments and among years, but not among granivore treatments. Seed bank richness was greater on unburned sites, and was likely due to variable precipitation among years. Native species had greater density on unburned plots and also varied significantly among years. Preliminary data suggest that high intensity or sequential fires in combination with alien annual grass invasions may drive native seeds banks toward local extinctions.

KEY WORDS: seed bank, Mojave Desert, fire, invasive species