Whispering Bells (Emmenanthe penduliflora), an obligate seeding annual
Fire as a disruptive force
Is fire a good thing for chaparral as many people claim? The answer is no because such a statement is overly simplistic and based on misunderstandings about the role of fire in the chaparral ecosystem.
Fire in the chaparral is a disruptive force leading to the selection of fire survival strategies. Since fire has been a recurring, although infrequent event, for millions of years in the chaparral, only those species that have adaptations that allow them recover after the flames will persist. Consequently, many chaparral plant species depend on some fire cue or post-fire environmental condition for maximal reproductive success. Does this mean the chaparral "needs" to burn? In the current environment, absolutely not. Before humans arrived on the scene, the fire return interval for chaparral was on the order of 30 to 150 years plus. But over the past century fires have increased dramatically because of human activity, in excess of what the chaparral can tolerate, especially in Southern California.
Old-growth chaparral (50 years old +) remains a vigorous plant community, continues to add biomass over time, and supports a dynamic population of animals. Chaparral plants have evolved fire-related adaptations in order to survive and carry on AFTER a fire, not because they "need" to burn. So it is better to think of chaparral plants as not "fire-adapted" per se, but rather adapted to particular fire regimes or patterns (involving season of burn, frequency, intensity, etc.).
Toyon (Heteromeles arbutifolia) resprouting after a fire.
There are three basic strategies plants use to respond to fire in the chaparral.
1. Obligate resprouters like toyon (Heteromeles arbutifolia) depend on resprouting from their underground root systems or burls to survive after a fire. Geophytes (perennials with fleshy, underground structures like bulbs or tubers) are obligate resprouters as well, but have a unique after-fire response. The enhanced light from the lack of cover stimulates many geophytes to produce large numbers of flowers.
2. Obligate seeders that are perennial shrubs, like many Ceanothus species, are destroyed in the flames and depend on seedlings to replace their populations. Their seeds require some fire cue (heat, charred wood, smoke) to germinate. Conifers like Tecate cypress (Cupressus forbesii) are also obligate seeders and deal with fire through serotiny, the tendency for cones to remain closed and on the tree until the heat of a fire opens them up, releasing its seeds. Most of the wildflowers that are seen in the post-fire environment are obligate seeding annuals or short-lived perennials. Again, this does not mean obligate seeders "need" fire, but rather are adapted to particular fire patterns.
3. Facultative seeders like chamise (Adenostoma fasciculatum) resprout AND germinate after a fire. A few Ceanothus and manzanita species are faculative seeders as well (most are obligate seeders as explained above).
A list of many chaparral plant species and how they respond to fire can be found in, "Fire, Chaparral, and Survival in Southern California." Further details can be found on our Book Excerpts page.
For the most part, California has been able to avoid the "catastrophic" forest fires that have plagued much of the western United States over the past few years.
If all these fires that occur in California on a regular basis aren't forest fires, what are they? California wildfires are typically shrubland fires and have nothing to with trees. Surprising to many is the fact that forests only comprised about 5 percent of the total acreage burned during the 2003 firestorm in Southern California.
The paradigm that has been repeated over and over is that fire suppression has caused an unnatural overabundance of vegetation, creating dangerous levels of "fuel" in California's wildlands. While this may be an accurate description for some forests, such as dry ponderosa pine forests in the southwest, it is not true for California chaparral.
Instead of blaming the fire suppression efforts of firefighters for causing a problem, we should be thanking them for holding back the flames. Despite the fact that fire frequencies in Southern California have increased dramatically over the past century, firefighters have been able to prevent those fires from destroying the kinds of natural resources we all enjoy so much. If the fires had been allowed to burn, as some have suggested, it is likely much more of the chaparral habitat that makes California so special would have been converted into large tracts of invasive, non-native weeds.
For more details on this subject, please see our Threats to Chaparral page. See our Forest Fires page for more information on forest fires and how best to deal with them.
The Post-fire Environment Examining the Use of Hydroseeding and Mulch After Wildfires
Shortly after wildfires are extinguished, the Burned Area Emergency Response (BAER) team arrives. This is an assemblage of scientists, foresters, and representatives from various federal agencies such as the Forest Service, Bureau of Indian Affairs, and the Fish and Wildlife Service, who are charged with recommending mitigation they feel is necessary to protect communities and resources from post-fire impacts. They come after every fire. The majority of the specialists fly in from other parts of the country and may or may not have knowledge of the local environment. They typically list a series of treatments such as mulching, sediment deflectors, channel clearing, and wattles (rolls of hay held together with plastic netting) to control erosion. Fortunately, seeding is generally no longer recommended.
Significant resources and huge numbers of personnel are employed to carry out the recommendations. Rolls of wattle are strung across gullies and hillsides, mulch is sprayed from trucks and dumped from planes and helicopters, and chain saws ring out as burned trees are removed. Hydromulch is a gooey combination of wood fiber, a sticky substance known as tackifier, and green dye. This paper-mache-like substance is applied to roadcuts and hillsides until the landscape is bright green again. County agencies and the California Department of Transportation (CalTrans) apply the same types of treatments.
Does mulching or seeding do any good? Post fire mitigation is a huge business. It also provides immediate, visible evidence that the government is doing something to help victims of the fire. Although companies involved will provide their own research supporting the need for their services, independent investigations measuring the actual effectiveness of mulching have been inconclusive. The impact of seeding wildland burned areas, however, is clear. Post-fire seeding can cause severe environmental damage including increased erosion, encouraging the spread of invasive weeds, and contributing to the elimination of native plant communities.
Unfortunately, some still ignore the science. Forty-three thousand pounds of non-native rye grass seed (Lolium multiflorum) were donated and distributed throughout San Diego County after the 2003 Cedar Fire.
Studies of seeded vs. non-seeded plots in Southern California have shown no evidence that the seeding of ryegrass significantly reduces the amount of surface erosion in the post-fire environment. In addition, ryegrass growth was at the expense of native cover with the greatest negative effect being on native, fire-following annuals. The use of ryegrass has also been associated with high mortality of Ceanothus shrub seedlings. In 1980, ryegrass seeding was responsible for spreading a large fire on Otay Mountain in San Diego County which lead to the elimination of chaparral on the site.
What about "native" seed mixes? The seed mix combined with mulch used by contractors after the 2003 Cedar Fire appeared to have a full assortment of native species, but a closer examination of the actual percentages revealed a different story. Most of the mix was grass seed. The largest portion (30%) consisted of a native wild ryegrass (Elymus glaucus) and 13% Vulpia microstachys, a native typically found in disturbed areas, not chaparral.
Another concern relating to post-fire seeding practices relates to the introduction of non-native weeds. Although seed companies guarantee their mixes, in practice it has proven impossible to eliminate contamination by alien species. For example, 800,000 pounds of grass seed was aerial seeded over more than 13,400 acres by a BAER effort on the Cerro Grande Fire scar around Los Alamos, New Mexico. This was the fire in 2000 that consumed over 47,000 acres and 350 homes. It was discovered later that an estimated 1 billion cheat grass seeds (Bromus tectorum) contaminated the seed mix. Cheat grass is an extremely invasive alien species that is creating significant ecological damage in many western forests and deserts by increasing fire frequency due to the unnatural addition of flashy fuels.
Preparing communities themselves for post-fire flooding by installing such things as check dams in flood-prone streambeds and channels, assisting with sand-bagging, and coordinating disaster education efforts are the most effective uses of post-fire mitigation resources. Spending millions of dollars mulching blackened hillsides is a waste of tax payer money.
Trash Mulch. Bits of plastic, foil, candy wrappers and other trash were contained in the mulch dumped by the Forest Service after the Gap Fire in the Los Padres National Forest above Goleta, CA. Photo by Brian Trautwein of the Environmental Defense Center.
CASE STUDY Post-fire recovery: Nature's way or our way?
By Wayne Spencer and Richard Halsey April 4, 2004 - San Diego Union-Tribune
Five months after the October firestorms, the hills are greening again in San Diego County. Rains came and the land held firm. Chaparral shrubs are resprouting from their bases or emerging from the blackened ground as tiny seedlings. Native wildflowers not seen in years will soon color the backcountry like floral phoenixes. And wildlife populations displaced by the fires are gradually recolonizing these renewing habitats, following a natural ecological process that has repeated itself uncounted times since before human memory.
So, were the millions of dollars spent to hydromulch the hillsides, broadcast seeds, plant trees or feed the deer money well spent? Did these interventions make a difference, or would we be better off just letting nature recover on its own?
The answers aren't simple and will require more time and data to answer fully, but in most cases available facts and scientific reason indicate that these well-intentioned actions were largely unnecessary, and some may be doing more harm than good.
It's essential to understand that fire and the erosion that naturally follows are ecological processes, like water cycles and nutrient cycles – like birth and death.
Science shows that wildland fires, including fires larger than those of last October, have periodically recurred in Southern California, long before humans arrived to witness them. If chaparral has burned and recovered countless times before, why does it need our help now? Didn't deer and other wild species endure numerous fires before we arrived on the scene? If erosion carved our canyons and deposited our sandy beaches, why try to stop it? Isn't the wisest course of action after a fire, "hands off, let Mother Nature do her thing"?
Not entirely, of course. To advocate a total hands-off approach to ecological recovery following fire would be to ignore our own presence and the myriad changes we humans already have made to the environment. We've built in floodplains and on landslide-prone hills; we've dammed rivers, creating traps for silts and sands that previously washed out to sea, thus forming our estuaries and beaches; we've introduced countless alien weeds, now poised to invade fire-denuded landscapes, and we've fragmented habitats with houses and roads, impeding the natural recolonization process for wildlife displaced by fires.
Because of these changes, there are circumstances where management intervention is necessary to protect human life and property following fire, or to protect our native ecosystem from further degradation. Unfortunately, under the post-fire pressure to "just do something," it appears precious management dollars may have been wasted where intervention is neither necessary nor helpful.
For example, broadcast seeding of either native or especially nonnative species, like rye grass, in hopes of reducing erosion has been widely debunked by scientific studies. Such actions are at best a waste of money, as most broadcast seed washes away before even germinating. At worst, broadcast seeding may actually increase erosion by hindering recovery of deeper-rooted native plants that are more effective at stabilizing soils. And successfully establishing a cover of nonnative annuals – referred to by firefighters as "flash fuels" – can increase fire ignition rates. Even if done with native seed mixes, the efficacy of wholesale hydroseed mulching of Wildcat Canyon, Scripps Ranch, and other areas is questionable, at best.
Soil erosion naturally increases after fire, exposing mineral soils and frequently increasing opportunities for seed germination. However, landslides and mudslides, like the Waterman Canyon disaster in San Bernardino County, are highly localized phenomena that depend on specific geological conditions. More than $1.25 million was spent laying down strips of mulch on Viejas Mountain near Alpine, ostensibly to control erosion and prevent landslides. However, Viejas Mountain is composed of gabbro-type soils that are not prone to landslides.
Viejas Mountain, San Diego County.
So why mulch Viejas or other open-space areas?
The U.S. Forest Service and other government agencies were under tremendous political pressure to recommend hydroseeding and mulching – to "just do something." Off the record, several Forest Service employees have stated, their words supported by previous Forest Service research, that these actions were largely cosmetic, with little hope of actually reducing erosion hazards or aiding ecological recovery.
What about caring for injured, displaced, or starving wildlife?
Efforts to rescue hungry deer by feeding them alfalfa or hay can lead to digestive ailments, bloating and dehydration. These unnaturally rich feeds are often dumped near roads, increasing roadkill risks for the animals attracted to them. And even if supplemental feeding does tide over starving deer in the short term, the artificially sustained population may exceed the capacity of the recovering landscape to support it, thus putting more pressure on the young vegetative growth, prolonging habitat recovery, and increasing erosion potential.
After the human losses, San Diegans grieve for the apparent destruction of our beloved natural environments. Images of the blackened landscape, the torched trees and the dead and displaced wildlife naturally raise fears that "nature has been destroyed," and "nature needs our help."
But nature is resilient. Repeated fires helped shape Southern California's native landscape, and it will rebound again on its own – except where changes we have made interfere with this natural process. In such cases, only carefully reasoned intervention, based on best available science rather than political expediency, should be applied. Otherwise, we should enjoy watching our natural environment quietly heal itself, as it has many times before.