Comparison of Community Structure Between a Burned and Unburned Mojave Desert Site Six Years Following Fire

Due to the historically uncommon nature of fire in desert ecosystems, most plants are not fire-adapted, which causes fires to have drastic effects on plant communities. We examined the composition of a Joshua Tree woodland site six years post-fire and compared it to an adjacent unburned site at Halloran Summit, San Bernardino County, CA. We asked the following research question: Are the burned and unburned sites different and if so, in what ways? We used transects and quadrat sampling to measure species richness, perennial and annual cover, density of Yucca shidigera and Yucca brevifolia, and to quantify signs of animal presence. Perennial species richness, perennial cover, and annual cover were significantly higher in the unburned site. The perennial species that represented the highest relative cover in one site (burned or unburned) had little to no relative cover in the other site. For example, blackbrush (Coleogyne ramosissima), a dominant shrub in the unburned (33.1% relative cover), was absent from the burned site. The most common non-native annual was Bromus sp. in the burned and Erodium cicutarium in the unburned site. There were significantly more animal burrows in the burned site. The burned area showed minimal recovery, and species composition was substantially different from the unburned control. This study adds to the limited information regarding desert fire recovery, specifically concerning post-disturbance successional patterns. Land managers can implement re-vegetation of early successional species that compete with exotic annual species to suppress non-native invasion of disturbed areas and allow slow-recovering natives to re-establish.