The fundamental problem with prescribed fires in California's native shrublands is that there is too much fire in these ecosystems already, threatening their continued existence. Prescribed fires do have a place in mixed conifer forests, but NOT in chaparral and sage scrub plant communities.
Why not in the chaparral?
1. Chaparral in California is threatened by too much fire.
Fire return intervals under 20 years can seriously compromise the ecological health of chaparral either by eliminating keystone plant species (and their associated animal partners) such as non-resprouting ceanothus and manzanita.
The fire departure map of the Cleveland National Forest on the left demonstrates the threat. All the hot colors are areas that have more fire than was historically the case. In other words, these areas are now being threatened with type conversion from native shrublands to non-native weed patches.
Map: Safford and Schmidt 2008. US Forest Service.
The impact of a cool season prescribed burn in the late 1980s: weeds and the destruction of the chaparral. Pinnacles National Park.
2. Unseasonal fire can eliminate a chaparral plant community.
There is a narrow window when prescribed burns can occur: in the cool season (late spring, just before summer). This is because in the winter and early spring months, chaparral plants have too much moisture within their tissues. They won't carry a fire. In the summer and fall, the wildfire risk is too high due to low moisture levels. As a consequence, prescribed burns are conducted in the chaparral when it is the most vulnerable: the plants are growing, the soil is still moist, many animal species are breeding, and birds are using the ecosystem during their annual migrations.
We do not know the exact mechanisms, but cool season burns probably cause significant damage to plant growth tissues and destroy seeds in the soil due to soil moisture turning into steam. The result? As can be seen in the photo above of a hillside in Pinnacles National Park, California, it can lead to immediate type conversion to a non-native weedlot. This was the site of a cool season prescribed burn in the late 1980's. The chaparral was destroyed and has never come back.
The following USFS document discusses the ecological risks of prescribed fire in chaparral and other plant communities:
The bottom line is that the potential for shifts in the plant community exists when the heat generated by prescribed burning is dissimilar to what would have been experienced with the fire regime that species evolved with.
The 2006 Sierra Fire, an escaped prescribed burn. Not only does the fire cause damage, but so do fire suppression activities such as dozer lines. Photo: Stephen Francis
2013 San Felipe Fire, San Felipe Valley Wildlife Area, CA. 2,781 acres burned. See below.
Why the National Park Service does NOT use prescribed fire in the Santa Monica Mountains
In the last forty years fire managers have promoted the idea that prescribed fire is necessary to protect ecosystems and communities by restoring fire's natural role in the environment to thin forest stands and to reduce hazardous fuels. This is true for western forests where the natural fire regime was frequent, low intensity surface fires started by lightning, and for many other ecosystems like southern longleaf pine forests, Florida palmetto scrub, and the Great Plains tall grass prairies. However, this is not true for the shrubland dominated ecosystems of southern California and the Santa Monica Mountains.
When Prescribed Fires Go Wrong The San Felipe Escaped Fire
On May 23, 2013, with the approval of the California Department of Fish and Wildlife, Cal Fire started a 100 acre "prescribed" burn within the protected San Felipe Valley Wildlife Area which is just east of the mountain town of Julian in San Diego County. The fire escaped and proceeded to burn more than 2,700 acres of fragile habitat within the protected area. Much of it had previously burned in the 2002 Pines Fire. Considering the ecological fragility of the area due to recent fires and the lack of any community nearby, we are wondering what these two agencies were thinking. Reburning an area that had burned 11 years ago causes serious ecological damage.
We visited the burn site and have obtained documents relating to the fire from the California Department of Fish and Wildlife which has jurisdiction over the Wildlife Area. Here are our findings:
the rationale for the Project was ecologically unsound
claims that the Project would reduce wildfire impacts and provide indirect community protection to Julian and Shelter Valley are unsupportable
the Project and the escaped fire caused significant environmental damage to a protected, rare, and environmentally sensitive habitat
fire suppression activities damaged riparian areas and possibly cultural sites
the Project violated the Dept. of Fish and Wildlife’s 2009 Land Management Plan for the San Felipe Valley Wildlife Area
Cal Fire may have violated its burn prescription plan
Cal Fire appears to have ignored a National Weather Service Wind Advisory on the date of the burn
In light of these conclusions we recommend the establishment of an official protocol for both the Department and Cal Fire to determine the efficacy and ecological impact of major vegetation treatments that includes an independent, outside review of projects while in the initial planning stages.
The remains of burned, eleven-year-old, recovering chamise shrubs can be seen on the right in addition to the significant soil disturbance caused by the bulldozers during the fire suppression action. The fragile desert streambed (below the line of sight) was also compromised by dozer action.
Fire Map: Above is the fire history map of the semi-desert area where the San Felipe escaped fire burned. As you can see, this landscape does not have much left in terms of habitat that hasn't burned over the last decade. It is not resilient to the kind of abuse caused by Cal Fire's out of control wildfire.
The burned Engelmann oak grove. These trees provided critical habitat before they were taken out by the fire. Engelmann oaks typically do not recover very well after being hit by a fire.
The future of the San Felipe Valley Wildlife area? Weeds? The landscape in the foreground was burned in 2012. It is across the street from the San Felipe escaped burn.
For more on why such a fire is so damaging to the environment and information on Cal Fire's ill-conceived plan to increase this kind of harmful activity across the entire state, please see our CalFire EIR page.