Fire, felling, and floods revamp Cajon Creek sensitive species habitat in a highly disturbed corridor

Riparian habitat along Cajon Creek in San Bernardino County, CA burned during the June 2002 Louisiana and Blue Cut fires. The wildfires affected 13,000 acres of watershed along an important corridor used by wildlife, utilities, and transportation. Natural processes and species in Cajon Creek and adjoining drainages were already disturbed by recreation and constrained by flood control channels. To reduce potential damage to railroad bridges from postfire flooding, burned trees in some segments of Cajon Creek were cut and removed. Sections of the creek are suitable habitat for three federally listed species – arroyo toad (Bufo californicus), least Bell’s vireo (Vireo bellii pusillus), and southwestern willow flycatcher (Empidonax traillii extimus) – and one Forest Service sensitive species – Santa Ana speckled dace (Rhinichthys osculus). Our study investigated how wildfire and tree clearing affected the riparian habitat and species. We sampled vegetation using line transects across the creek in unburned, burned, and burned-and-cut areas. Rapid habitat recovery was generally observed, but live tree height was below pre-burn measures 4 years post-fire. Shrubs and herbaceous plants in the burn area benefited from overstory reduction. Tree removal initially reduced vegetation height and cover, but by 2006 it had grown into clusters of dense, impenetrable thickets. Heavy flooding during 2005 scoured herbaceous vegetation from both the stream channel and flood plain. Post-fire surveys revealed continuous use of Cajon Creek by birds, amphibians, and speckled dace. Riparian species are evidently highly resilient to disturbance in this dynamic ecosystem.