PARENT SESSION
Symposium #12: Natural Recovery and Restoration of Disturbed Desert Environments in the Mojave Desert .

Organized by: RH Webb and KH Berry
Tuesday, August 6. 8:00 AM to 11:30 AM. Maricopa Meeting Room, TCC.

Natural recovery of perennial vegetation in severely disturbed sites in the Mojave Desert.

Thomas, Kathryn^*,1, Webb, Robert², ¹ US Geological Survey, Flagstaff, Arizona² US Geological Survey, Tucson, Arizona

ABSTRACT- Natural recovery of perennial vegetation was measured at disturbances for which the time since vegetation removal was known. These dated disturbances are in utility corridors (10-35 years recovery), military training camps (about 40 years recovery), and abandoned mining towns (50-93 years recovery). These sites are in a variety of vegetation types spanning an elevation range of 300 to 1730 m elevation. Initial analysis shows that native species will reestablish in a discrete disturbance without human intervention, although the variability in species composition of initial colonizers is high. Total perennial cover, regardless of species composition, recovers in less than 100 years; recovery of the original species composition may require up to several thousand years. Lower-elevation, monospecific plant assemblages, dominated by Larrea or Atriplex, recover more quickly than mixed assemblages or the higher-elevation Coleogyne assemblages. The life history of colonizing species provides a framework to understand and project the recovery trajectory for a disturbed site. While species with similar life-history strategies may have a functional role in disturbance recovery, the recovery trajectory is also a function of the soil type and the age of the geomorphic surface; residual soil compaction; climatic history since disturbance; and the impact of any post-abandonment disturbance. Climate change, atmospheric CO₂ enrichment, and introduction of invasive exotic species may confound prediction of a natural recovery trajectory based solely on interpretation of existing dated disturbances.

KEY WORDS: mojave, vegetation recovery, dated disturbances