PARENT SESSION
Oral Session #27: Fire Ecology.
Presiding: C. Allen
Tuesday, August 6. 8:00 AM to 11:30 AM. Graham Meeting Room, TCC.
The effects of fire in Sonoran plant communities.
Alford, Eddie*,1, Brock, John2, 1 U.S. Forest Service, Phoenix, Arizona2 Arizona State University East, Mesa, Arizona
ABSTRACT- The effects of fire on Sonoran Desert plant communities were determined by analyzing the influence of anthropogenic and climatic factors on fire regimes and measuring the responses of plants on a time-since-fire (tsf) gradient. An upward trend in the number of fires has occurred during the past 45 years in the Sonoran Desert; however, there was not a significant (P <0.05) trend in hectares burned. The positive trend in number of fires was consistent with an increase in the population of Maricopa County and an increase in traffic along major Sonoran Desert highways in the Tonto National Forest. The number of hectares burned did not change with increased winter, summer, spring, fall or total annual precipitation. However, the number of fires and hectares burned increased with increased precipitation from two and three consecutive winters precipitation. Overall plant density decreased as canopy cover increased on a tsf gradient. Native species most impacted by fire were saguaro (Carnegiea gigantea) and foothill paloverde (Cercidium microphyllum). Foothill paloverde recovered, with respect to density and canopy cover, 21 years after fire. Repeated fires have caused an increase in density for purple three-awn (<1Aristida purpurea) and desert senna (Cassia armada) and a decrease in native species such as Krameria grayi), wolfberry (Lycium spp.), and creosote bush (Larrea tridentada).
KEY WORDS: desert, Sonoran, fire