Effects of fire on Sonoran desert plant communities

The number of fires has increased during the past 45 years in the Sonoran Desert within the Tonto National Forest of central Arizona. The positive trend in the 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 population in Maricopa County or increased traffic along Sonoran Desert highways. However, number of hectares burned was influenced by the occurrence of two and three consecutive winters’ precipitation. Overall plant density decreased as canopy cover increased on a time-since-fire (tsf) gradient. Native species most impacted by fires were saguaro (Carnegiea gigantea) and foothill paloverde (Cercidium microphyllum).