Thursday, August 9, 2007 - 2:30 PM

COS 123-4: Does post-fire seeding in a Mojave Desert shrubland rehabilitate habitat for the desert tortoise?

Lesley A. DeFalco, Todd C. Esque, Kenneth E. Nussear, Kristina Drake, Sara J. Scoles, and Philip A. Medica. US Geological Survey, Westen Ecological Science Center

Arid land rehabilitation is often implemented with little understanding of the ecological processes that drive recovery. Wildfires in the Mojave Desert alter habitat for the threatened desert tortoise (<i>Gopherus agassizii</i>) by removing shrub structure and enhancing invasive annual grasses. In response, millions of dollars are spent to seed burned areas with native species representative of intact tortoise habitat, but the fate of these seeds and the impacts of fluctuating rainfall and displacement by invasive grasses on vegetation re-establishment are largely unknown. In June 2005, lightning ignited wildfires that burned almost a half million acres of tortoise habitat in southern Nevada. Burned habitat was seeded in December 2005 to accelerate the establishment of shrubs and herbaceous forbs. We evaluated the success of seeding and determined whether tortoises used seeded burned areas. Plant establishment was low in the first year following seeding, and seedling densities were not significantly different between seeded and unseeded treatments; this result reflects below-average rainfall during the six months following seeding (41%) and the potential suppression by invasive grasses. Likewise, tortoise activity – as determined by the presence of live tortoises, burrows and fresh scats – was not enhanced by seeding. However, less tortoise activity in the burns compared with unburned areas suggests that tortoises moved away from burned habitat one year after the fire. Summer movements of tortoises along the burn margin indicate that tortoises are foraging in burned areas, where annual plant production is abundant, while remaining close to unburned remnants that provide shrub cover to escape thermal extremes.

See more of COS 123 - Ecology of arid and semiarid habitats: I
See more of Contributed Oral and Poster Abstracts

See more of The ESA/SER Joint Meeting (August 5 -- August 10, 2007)