Sources of Ignition. Native Americans: Significant impact probably for less than 5,000 years. What happened before that? Natural: In 25 years, only 2 lightning fires have been recorded in the Santa Monica Mountains. (Photo of Yahi Indian, Ishi)
Natural systems adapted and survived for millions of years before humans ever entered the scene. Fire was used in aboriginal times to modify the environment in a way that best suited survival needs. The historic observation that some Native Americans used fire to modify the landscape does not mean it is something we should emulate today.
The best fire history data we have applies to conifer forests using fire scar dendrochronology (tree ring studies). This information does not allow us to distinguish between anthropogenic (human caused) or lightning caused ignitions. So it is extremely difficult to determine the frequency or impact of Native American burning. However, despite such limitations, it is still possible to conclude that in certain forests with high lightning frequencies, Native Americans had little, if any, significant impact. In those systems, modern fire suppression, over grazing, and past logging practices have created excessive fuel loading problems and an effort to return them to more natural conditions with fire is a reasonable goal.
In contrast, the relative impact of Native American burning in the coastal portions of California was probably quite significant. Ethnographic studies and other historical documents show that California Indians were responsible for extensive burning and type-conversion of chaparral and other shrublands to grasslands in order to increase favored game species, protect themselves from predators (the favored habitat of the California grizzly bear was chaparral), and as a tool of warfare. They almost certainly increased fire frequencies over what was naturally possible due to lightning. For example, in the 153,000 acre Santa Monica Mountain National Recreation Area only 2 lightning fires have been recorded over the past 25 years.
Ecosystems within the coastal region of Southern California were likely the most heavily impacted by Native American burning and may have ultimately set the stage for the successful spread of invasive European grasses in the early 1800's. Southern California oak savannas appear to have been dominated by sage scrub systems that were modified by Native American burning, then finally eliminated over much of its range by post-European grazing activity and burning. Suggestions that Native American burning activity was an essential and natural part of the oak woodland environment are not reasonable when the system thrived for millions of years before the arrival of human beings on the North American continent. The gradual disappearance of oaks we have witnessed over the last century likely began with their first human contact thousands of years ago.
The important point is that Indian burning practices were performed to modify the landscape in an artificial manner and probably resulted in the elimination of large tracts of native shrubland communities.
This is not the type of pattern we should be emulating if our desire is to preserve and protect California’s remaining distinctive ecosystems. Each has its own, unique fire regime and each can be easily compromised if fire is used inappropriately. In addition, we must contend with the invasion and continued expansion of alien weed species (especially grasses) into native ecosystems due to disturbance and shorter fire return intervals. This threat did not exist for Native Americans.
In southwestern California, fire frequencies continue to increase with our growing population. Laying more fire on the ground without careful consideration of modern environmental risks will likely have negative consequences on the health and sustainability of natural ecosystems.
Also see "Misunderstanding Natural Fire Return Intervals" below, but first a reality check regarding Native Americans.
Native Americans as Sovereign Human Beings
First European settlers tried to push them out of the way. Then the United States Government tried to exterminate their cultural identity, with a significant faction encouraging genocide. By the 1960's it seemed everyone wanted to be an "Indian." Now, after hard fought legal victories securing traditional hunting and fishing rights and regaining stolen land, in addition to newly gained wealth derived from gaming activities, predjudice is rising up again against American's original inhabitants. It's time to get educated.
Start here by reading the two books listed to the right. The first, "Neither Wolf nor Dog" by Kent Nerburn, gives an excellent account of how the Lakota (Souix) see the dominant society today and how different the Native American perspective really is on a variety of issues (the land, nature, spirituality, ownership, and junk cars).
The second book, "Blood Struggle" by Charles Wilkinson, is an outstanding description of the past 75 years of Native American efforts to regain both their rights and their sovereignty.
Another book with a very special message is "Nature's Way" by Ed McGaa (Eagle Man). Ed is a Lakota who eloquently describes how to reconnect to the North American natural environment from the perspective of those who knew how to do it first.
Many chaparral stands in California are either moderately or significantly altered from their historical fire regime range. Unfortunately, some classification systems currently under development, such the multi-agency Fire Regime Condition Class (FRCC) model and the LANDFIRE project, thus far fail to distinguish between altered by too few or too many fires. Vegetation communities are classified on a scale from 1-3. "1" meaning a community is within its natural fire return cycle, "2" for having missed several natural fire return intervals, and "3" for a community severely out of its natural cycle.
The basic problem of these determinations is they are based on forest studies and are not applicable to chaparral or other shrubland type systems. In addition, the baseline reference point is "pre-settlement" conditions which ignores the potential negative impacts Native American burning may have caused to native ecosystems.
All of the chaparral in California has been classified as either condition class 2 or 3 under these classification systems. Consequently, there is a presumption that all chaparral “needs” to be burned in order to remain healthy and that increasingly rare, old-growth chaparral is “decadent” and has little, if any, resource value. Such perceptions completely misinterpret chaparral ecology and are not supported by current scientific research nor the natural resource or recreational needs of future citizens.
Although the term “decadence” may be helpful to wildland firefighters when describing chaparral stands that have accumulated dead material, it has pejorative connotations and does not reflect our current understanding of the chaparral ecosystem. Specifically,
- The continued ability of chaparral stands nearly a century old to maintain productive growth has been confirmed by multiple investigations (Hubbard 1986, Larigauderie et al. 1990),
- The accumulation of biomass steadily increases for at least 45 years in chamise chaparral (Specht 1969) and probably more than 100 years in other types, especially north facing stands and,
-Shrubs in older chaparral communities are not constrained by limited soil nutrient levels (Fenn et. al. 1993).
While it is true most obligate seedingCeanothus species will die as a stand reaches 30-60 years of age, others remain an important part of chaparral stands over 90 years old (Keeley 1973, 1975). All of these species have dormant seed banks that ensure their long term persistence in the ecosystem even if fires only occur every century or so. When spaces do appear in the chaparral, living plants quickly fill the void. For example, chamise shrubs that have not experienced fire for at least 80 years continually send up new stems from their base (Zedler and Zammit 1989).
Not only do mature shrubs continue growing over time, but seeds from the majority of species common to north facing, mesic chaparral stands require long fire-free environments before being able to germinate. Moisture protecting shrub cover and leaf litter are needed to nurse the seedlings along. Plants such as scrub oak (Quercus berberidifolia), holly-leafed cherry (Prunus ilicifolia), and toyon (Heteromeles arbutifolia) fall into this category. So rather than being a “decadent” habitat of dying shrubbery, many mature chaparral stands are just beginning a new stage of growth after fifty years of age.
Although chaparral is considered a “fire-adapted” ecosystem and some types do accumulate significant amounts of dead wood, the system certainly does not need human caused ignitions to remain healthy especially in light of the increased number of fires occurring in shrublands today, especially in Southern California. The idea chaparral needs to burn is related more to human misconceptions than any ecological process (Halsey 2005).
Senescence risk, which is the risk of loosing species if fires are too infrequent, has never been demonstrated for any chaparral in any part of the state. In fact, studies show excellent ecosystem post-fire recovery following 150 years without fire. Based on our knowledge of historical burning in chaparral, old-growth stands are clearly within the range of historical variability. Immaturity risk on the other hand, which is the risk of loosing species if fires are too frequent, has been repeatedly demonstrated in countless studies.
Unlike forests, we don’t really know what the natural fire return interval is for each type of chaparral, but we have convincing evidence that fires occurring closer than 15 - 20 years apart can threaten many of them (Zedler et al. 1983, Haidinger and Keeley 1993, Keeley 1995, Zedler 1995, Jacobson et al. 2004). Local extinctions of certain species can also occur if some chaparral types are not allowed to exist past 50 - 75 years. In fact, even the California Fire Plan acknowledges that,
“California has a complex fire environment, with multiple climates, diverse topography and many complex vegetation communities. CDF data on assets at risk to damage from wildfire is incomplete.” And, “unnaturally frequent patterns of fire can overwhelm the inherent ability of many fire adapted species of plants to sustain themselves.”
Applying the right knowledge with the appropriate ecosystem is crucial if we want to properly manage our state’s wildlands. Since chaparral is California’s most extensive plant community, it is prudent to make sure we understand both its particular fire regimes and its sensitivities to changes in those regimes.
There was a period during the last century when one of the primary objectives of land managers was to increase and “improve” range land by eliminating chaparral through increased fire frequency. With growing population pressures, the increasing need for open space, and an expanding wildland/urban boundary, the expectations of land managers is quickly changing. They need to not only protect life and property from wildfire, but also to properly evaluate the demands of competing interests in order to prevent the wholesale elimination of California’s native landscapes.
We need to move away from viewing chaparral as merely fuel and instead begin to appreciate its significant natural resource value.
Fenn, M.E. M.A. Poth, P.H. Dunn, and S.C. Barro. 1993. Microbial N and biomass respiration an N mineralization in soils beneath two chaparral species along a fire-induced age gradient. Soil Biol. Biochem. 25:457-466.
Haidinger, T.L., and J.E. Keeley. 1993. Role of high fire frequency in destruction of mixed chaparral. Madrono 40: 141-147.
Hubbard, R.F. 1986. Stand age and growth dynamics in chamise chaparral. Master’s thesis, San Diego State University, San Diego, California.
Jacobsen, A.L., S.D. Davis, S. Fabritius. 2004. Vegetation type conversion in response to short fire return intervals in California chaparral. Annual Meeting of the Ecological Society of America, Portland OR. Abstract.
Keeley, J.E. 1973. The adaptive significant of obligate-seeding shrubs in the chaparral. Master’s thesis, California State University, San Diego. 79 p.
Knudsen, K. and D. Magney. 2006. Rare lichen habitats and rare lichen species of Ventura County, California. Opuscula Philolichenum 3: 49-52.
Larigauderie, A., T.W. Hubbard, and J. Kummerow. 1990. Growth dynamics of two chaparral shrub species with time after fire. Madrono 37: 225-236.
Specht, T.L. 1969. A comparison of the sclerophyllous vegetation characteristics of mediterranean type climates in France, California, and southern Australia. I: Structure, morphology and succession. Aust. J. Bot. 17: 227-292.
Zedler, P.H. 1995. Fire frequency in southern California shrublands: biological effects and management options, pp. 101-112 in J.E. Keeley and T. Scott (eds.), Brushfires in California wildlands: ecology and resource management. International Association of Wildland Fire, Fairfield, Wash.
Zedler, P.H., C.R. Gautier, G.S. McMaster. 1983. Vegetation change in response to extreme events: the effect of a short interval between fires in California chaparral and coastal sage scrub. Ecology 64: 809-818.
Zedler, P.H., and C.A. Zammit. 1989. A population-based critique of concepts of change in the chaparral. In S.C. Keeley (ed.), The California Chaparral: Paradigms Reexamined. The Natural History Museum of Los Angeles County, 1986.
