Post-fire erosion control research on the San Dimas Experimental Forest: past and present

Abstract

The San Dimas Experimental Forest (SDEF) was established in the early 1930s to document and quantify wildland hydrology in the semiarid chaparral-covered steeplands of southern California. Concomitantly, the nearly seventy years of accumulated watershed research in this fire-prone ecosystem has produced invaluable information on post-fire erosion and the effectiveness and consequences of post-fire erosion control treatments. On average, first-year post-fire watershed sediment yield is 35 times greater than comparable unburned annual levels. This accelerated erosion can cause site degradation and threatens life, property, and infrastructure at the adjacent wildland/urban interface. To mitigate undesirable consequences of post-fire accelerated erosion, land managers have developed a program of hillslope and stream channel emergency rehabilitation treatments as erosion control measures. The SDEF has been the site on which many of these erosion control practices, both past and present, have been tested. In the 1960s, some labor-intensive treatments were shown to have no effect on reducing post-fire erosion. At the same time, more radical ground-disturbing treatments that were marginally effective in the short-term have persisted on the landscape and altered the subsequent sediment fluxes through these watersheds. In September 2002, virtually the entire SDEF burned in the Williams Fire. This allowed the implementation of a new series of emergency rehabilitation treatments for which the effects and consequences are largely unknown. Preliminary results suggest that an aerial application of polyacrylamide did nothing to reduce post-fire sediment yield, but that prefabricated wooden channel checks may be an effective post-fire rehabilitation tool.

Citation

Wohlgemuth, Peter M. 2003. Post-fire erosion control research on the San Dimas Experimental Forest: past and present. In: Renard, Kenneth G.; McElroy, Stephen A.; Gburek, William J.; Canfield, H. Evan; Scott, Russell L., eds. First Interagency Conference on Research in the Watersheds, October 27-30, 2003. Washington, DC: U.S. Department of Agriculture, Agricultural Research Service: 645-650.