Post-Fire Recovery in the Arizona Upland of the Sonoran Desert

Fire-prone invasive plants fueled fires that converted this formerly diverse Sonoran Desert landscape of small trees and tall Saguaro cactus into an impoverished shrubland.

By Garry Rogers.

The Sonoran Desert’s diverse vegetation of small round trees, tall cacti, and understory shrubs is remarkably beautiful. I was fortunate to spend my early career studying the desert. One of my projects involved wildfire.

Following fires in 1974, my classmate Jeff Steele and I used repeated observations of permanent plots and transects to measure fire-related adaptive responses of perennial plant species and communities.  We expected to find that desert plants were recovering by sprouting from unburned roots and stems and from seeds buried in the soil.  We expected this because of the “fire is natural” rebellion that was opposing traditional “Smokey the Bear” fire suppression efforts.  We wanted to be rebels too.  What we found was that positive adaptations that would allow recovery after burning were common, but they were weak.  Most plants just burned to death and stayed dead.  Return of the original plant community was taking place very slowly.  We projected that several decades would be required for full recovery.

After we published the initial results, both sites burned again.  We repeated our observations of the plots and transects several times.  In 2008, I reported that 22 years after the second fires, recovery had not occurred (Turner et al. 2010).  Only a few fast-growing members of the original plant community had returned, and large numbers of fire-prone invasive alien plants occupied both sites.  A brief inspection in 2015 indicated that conditions had not improved.  It appears unlikely that the original diverse vegetation dominated by tall Saguaro Cacti and round green Paloverde trees will ever return.  Fighting fires in the desert was the right strategy.

Perhaps no fire in the Sonoran Desert has been natural since the introduction and spread of exotic annuals.  Both frequency and intensity have increased.

Climate Change and Desert Fire

The lengthening drought in the region occupied by the Sonoran Desert is accelerating the replacement of the original plant communities by fire-prone weeds. Weed landscapes are spreading and fires are becoming more frequent. Watching the disappearance of the original complex desert vegetation is one of my saddest experiences.

• Citation:  Rogers, Garry, and Jeff Steele.  1980. Sonoran desert fire ecology.  Pages 15-19 in M. A. Stokes and J. H. Dieterich, technical coordinators.  Proceedings of the fire history workshop.  U. S. Forest Service, General Technical Report RM-81.  Link to PDF copy of paper.
• Reference:  Tuner, Raymond M., Robert H. Webb, Todd C. Esque, Garry Rogers.  2010.  Repeat photography and low elevation fire responses in the southwestern United States. Pages 223-244 in R. H. Webb, D. E. Boyer, and R. M. Turner, eds. Repeat photography methods and applications in the natural sciences. Island Press, Washington, DC. 530 p.