PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Variable trajectories of burned salt desert habitat in the Great Basin.
Haubensak, Karen1, D'Antonio, Carla 1, 2, Wixon Keller, Devin*,1, 1 Exotic and Invasive Weeds Research Unit, Reno, NV, USA2 Environmental Studies Department, Santa Barbara, CA, USA
ABSTRACT- Fire frequencies have increased dramatically in the Great Basin since the invasion of cheatgrass (Bromus tectorum). The extent to which native species regenerate or recover in burned sites may depend on a suite of factors, including the cover of invasive exotics and environmental variables like fire intensity, soil texture and nutrient status, and distance from roads and unburned areas. We surveyed a total of 24 sites that burned in 1998 plus 10 adjacent control sites in 2003 and 2004 in salt desert habitat of the Great Basin in the northwestern region of Nevada. Our sampling area encompassed approximately 27 km2. We surveyed density and cover of all species, including the two dominant native shrubs, shadscale (Atriplex confertifolia) and budsage (Artemisia spinescens), and all exotics. We simultaneously collected soils and measured texture, cations, total carbon and nitrogen pools, pH and salinity. We assessed the extent to which the region is returning to native dominance. Budsage did not occur in any of the burned sites. On the other hand, shadscale appears to be recruiting continuously since the 1998 fire, although its cover is on average 30% of that in control sites. In burned sites, shadscale cover declines as exotic cover increases (r2 = 0.21, p = 0.02). Despite dominance and continuous cover by annual exotic species in burned sites, we found no significant difference in aboveground NPP in burned compared to control sites. Overall, we observed a large degree of variability in site recovery. We used ordination analyses to explore the relative importance of different sources of variability.
Key words: cheatgrass, invasion, fire, exotic