INTRODUCTION: I have spent my entire career studying and photographing plant adaptations, and I still think many species in fire-prone areas of the earth have evolved to survive wildfires. By surviving fire I am primarily referring to perpetuation of the species through resprouting from lignotubers and dispersal of seeds following wildfires. This report focuses on some of these remarkable adaptations. Although the chaparral is dominated by shrubs that are adapted to periodic brush fires, fire intervals that are too frequent can be very destructive to this plant community. Population growth, urbanization, vehicle traffic, and the introduction of alien weeds has altered the natural environment in southern California. The human impact on this ecosystem in some areas has been disastrous, particularly where slopes, ridges and canyons of prime watershed have been converted into housing developments. Not only is this urban sprawl destructive to a unique ecosystem, it poses a serious threat to residents and firefighters. In this Mediterranean climate, the fire danger is exacerbated by high temperatures, low humidity, strong, descending "Santa Ana" winds, and powerful, "tornadic" winds generated by fires. In the Paradise Fire of 2018 these winds exceeded 100 mph. I have seen fires spread through previously burned areas covered by alien weeds, such as dense mustards and annual grasses, only to spread into nearby housing developments that were burned in the previous fire. In San Diego County the devastating Witch Creek Fire of 2007 destroyed about 1500 homes and followed nearly the same path as the Cedar Fire of 2003 that destroyed over 2,000 homes. Alien weeds on north side of Owens Peak north of Palomar College (15 April 2019). They include mustards (Hirschfeldia incana & Brassica nigra). The dense annual grasses in foreground include slender wild oat (Avena barbata), red brome (Bromus madritensis ssp. rubens), ripgut (B. diandrus), and foxtails (Hordeum species). There are many other species of alien weeds on this slope following the substantial rainfall of winter 2019. During drought months of late summer and fall, these dried-out weeds can definitely carry a fire, especially when fanned by dry Santa Ana winds. Dense annual grasses & mustards on south side of Owens Peak following their spring growing season. Fast-moving wildfires can sweep across these dry slopes during drought months of late summer and fall. There are methods of reducing the fire danger in forested areas, such as control burning (prescribed burning) and clearing of understory brush, although there is disagreement among fire ecologists on which of these methods are beneficial to the environment and which are detrimental. Fire is a natural force of the environment related to climatic factors such as prolonged drought, temperature and wind. Of course, I am referring here to natural fire, not fires caused directly or indirectly by people. In his book The Wild Fire Reader: A Century of Failed Forest Policy (2006), George Wuerthner discusses some of the beneficial aspects of natural fire, particularly in forest ecosystems. His section on "Wildfire Myths" (Part One) is especially interesting. Each myth is followed by a brief explanation of the "truth." The myths are controversial and include "fire is bad and needs to be suppressed," "big fires are the result of too much fuel," "logging mimics fire," "big fires can be stopped," "fire 'destroys' forests and wildlife," "fire 'sterilizes' the land," "livestock grazing can prevent fires," "salvage logging after a fire is necessary to restore forests," and "prescribed burning is an adequate substitute for wildfire." The chaparral is more problematic with the tremendous population densities in these areas. This is a "heated" controversial subject among state and federal agencies, politicians and environmental biologists. I personally think future housing developments should be banned on upland slopes and ridgetops in fire-prone areas. Developments adjacent to fire corridors should have buffer zones with greater areas of defensable open space. Homes should be built with fire-resistant materials and with more space between them. Of course, this will greatly decrease the profits of land developers. I am always reminded of housing shortages, but MAYBE WE ALL CAN'T LIVE & WORK IN SAN DIEGO COUNTY & ELSEWHERE IN SOUTHERN CALIFORNIA. Many of these topics are discussed in Richard Halsey's 2005 book Fire, Chaparral, and Survival in Southern California. Sunbelt Publications, Inc., PO Box 191126, San Diego, CA.

Devastating Lahaina Fire On Island of Maui Aug 2023   Deadliest WildFire In U.S. History Killing 100+ In 80 MPH   Wind: A Horrific, Apocalyptic Inferno Destroying Town.      Massive Forest Fires in Canada Spring/Summer 2023      Comet Fire On Campus Of Palomar College Jan 2021      Sycamore Fire Twin Oaks Valley San Marcos Dec 2020      The October 2007 Witch Creek Fire San Diego County      Witch Creek Fire Followers In Spring 2008 (5 Parts)      The October 2003 Paradise Fire In San Diego County      The October 2003 Cedar Fire In San Diego County      Lightning: The Primary Cause Of Natural Forest Fires      Images Of Lightning Bolt & Lightning Struck Pine   1.    Brush Fire In Coastal Sage Scrub Of Southern California   2.    See A Giant Smoke Cloud North Of Palomar College   3.    Charred Leaves That Fell On The City Of Escondido   4.    Rattlesnake Crawling On Ashes One Day After A Fire         5.    Exfoliating Boulders & Resproutings Shrub After Fire   6.    Subterranean Lignotuber That Resprouts After Fire   7.    Coast Live Oaks Resprout From Trunk & Upper imbs   8.    Burned Hillside Covered With Beautiful Wildflowers   9.    Three Species Of Spectacular Post-Burn Wildflowers 10.   Allelopathy In Calif. Coastal Sage Scrub & Chaparral 11.   Fire Seeds Of Ceanothus That Germinate After Fire 12.   Seed Cones Of Knobcone Pine That Open After Fire 13.   Seedlings Of Tecate Cypress Following A Wild Fire 14.   Seed Cones Of Lodgepole Pine That Open After Fire 15.   Combustible Resins From Douglas Fir & Pine Trees 16.   Fire Adapted Australian Shrubs (Hakea & Banksia) 17.   Coastal Sage Scrub Bordering Palomar College 18.   Ant Surveys To Study Effects of Wildfires 19.   Summary and Conclusions 20.   References Cited

Imagine the following scenario: It is a warm, fall afternoon in the foothills of southern California. The air is still and dry, with only the occasional calls of wrentits and scrub jays from a nearby canyon. Suddenly, a funnel of black smoke rises from the dry brushlands. As the late afternoon breezes begin to pick up, the smoke enlarges into a billowing cloud that resembles an atomic bomb explosion. Soon the sun is blotted out by a huge mushroom cloud and the air is filled with ashes and the distant sounds of sirens and air horns. This is a brush fire out of control, a common occurrence in the parched hillsides of southern California and the beginning of one of nature's most fascinating cycles of death and renewal. In fact, this scenario was precisely replayed on 22 October 22 1996 in the hills of coastal sage scrub bordering the east side of Palomar College.

Lightning bolt over north Twin Oaks Valley photographed with my Nikon film camera on a tripod at 3:00 AM during summer 2005! There are many causes for wildfires, including man-made and natural; but lightning is certainly one of the major causes of natural fire.

A leader from a bolt of lightning can travel at speeds 60,000 meters per second (13,670 miles per hour), and can reach a temperature approaching 30,000 degrees Celsius (54,000 degrees Fahrenheit), hot enough to convert silica into glass. Large bolts of negative lightning from the clouds carry an electric current of up to 100,000 amps. Lightning rapidly heats the air in its immediate vicinity to about 20,000 degrees Celsius (36,000 degrees Fahrenheit), about three times the temperature of the surface of the sun. This compresses the surrounding air and creates an acoustic wave that is heard as thunder.

The reason that a metal top car is a reasonably safe place to be in a severe lightning storm is NOT the rubber tires. Hopefully the lightning will pass safely through the outer metal shell of your vehicle and into the ground. However, there are cases where the electrons remain in the metal body and don't travel to the ground until you make the fatal connection by stepping out.  See: Faraday Cage

Lightning: The Primary Cause Of Natural Forest Fires       Images Of Lightning Bolt & Pine Struck By Lightning     A Hollow High Voltage Overhead Transmission Line

In terms of urbanized habitats, California's fire storms are one of nature's most catastrophic and destructive forces. The fast-moving flames can sweep across entire hillsides in seconds, and can suddenly change direction with shifting winds. But in terms of natural vegetation, these seemingly ruthless brush fires can be very beneficial to some fire-adapted species. There are actually five climatic regions of the world with a similar regime of mild, wet winters and hot, dry summers, including California, Chile, the Cape region of South Africa, southwestern Australia, and the Mediterranean. Although they may have entirely different plant species, all of these regions have similar chaparral-like brushlands with wildfires during the late summer and fall.

If you walk through the chalky gray ashes and charred remains of a lifeless shrub forest immediately following a fire, it is hard to imagine anything ever growing here again. Often the ashy soil is littered with flakes of granodiorite that split off of large boulders--proof of the intense heat of the flames. Like peeling off the layers of an onion skin, this is a major source of exfoliation of granitic formations in southern California. However, this bleak and silent setting of grays and blacks is only a temporary stage in a complex series of miraculous events in which nature will gradually restore the original vegetation.

Katherine J. Kendrick, Camille A. Partin and Robert C. Graham. 2015. "Granitic Boulder Erosion Caused by Chaparral Wild fire: Implications for Cosmogenic Radionuclide Dating of Bedrock Surfaces." The Journal of Geology, 2016, volume 124, pp. 529-539.

Available on-line at: authors.library.caltech.edu/69430/1/686273.pdf

Brush fires in southern California typically occur during the drought months of summer and fall, the so-called "fire season." The native thickets of shrubs, known as chaparral (and coastal sage scrub), are tender dry by late summer and many species are especially combustible due to their high content of volatile terpene oils and resins. The flames are sometimes fanned by brisk "Santa Ana" winds, producing a raging inferno that sweeps out of control toward the ocean. Thickets of dense, impenetrable chaparral, with masses of dead branches and leaf litter which took decades to accumulate, are recycled into rich, nutrient soil ash within minutes. With the coming of winter rains, small green sprigs of grasses and annual wildflowers begin pushing through the rain-soaked, ashy soil. Within weeks the barren gray and black slopes are transformed into velvety hills of green.

By this time, green leafy branches have already developed from the bases of charred shrubs such as chamise (Adenostoma fasciculatum) and mazanita (Arctostaphylos gladulosa), having resprouted from vegetative buds in deep subterranean woody stumps called basal burls or "lignotubers." These remarkable woody structures are truly adapted to periodic brush fires and are a major factor in the survival of native shrubs in the chaparral of California. [See the chamise lignotuber at left.]

To appreciate the tenacity of these basal burls, consider the mission mazanita (Xylococcus bicolor). In September 1993 the Palomar College Field Botany class found a small mission mazanita burl that was washed out along a dirt road north of Escondido (northeast of Palomar College). The burl had undoubtedly been exposed to the air since the heavy rains of the previous winter. We planted the burl in a test plot at the WAYNE'S WORD office and burned off the exposed branches with a small "ground fire." The staff at WAYNE'S WORD gave the burl several "simulated" rains, and within one month following the fire, new shoots began to appear from the charred stump.

Briarwood pipes are made from the lignotuber (burl) of Erica    arborea, a Mediterranean shrub of the heath family (Ericaceae). Like the burls of manzanita (Arctostaphylos) in the California chaparral, briarwood also resprouts from subterranean basal burls after a brush fire. Due to arid habitats and infertile, rocky soils, it usually takes about 30 years or more for a burl of five to ten pounds to form. A ten pound (4.5 kg) burl is large enough to make about one dozen pipes. Briarwood burls are composed of very dense, fire-resistant wood. The pipes can withstand the heat of burning tobacco which may exceed 700 degrees Fahrenheit. High quality briarwood also absorbs moisture from the tobacco, thus producing a drier smoke that is highly prized by pipe smokers. Compared with other hardwoods, such as hornbeam (Carpinus), beech (Fagus), chestnut (Castanea) and cherry (Prunus), briarwood does not impart an unpleasant taste to the smoke.

When the trunk and limbs of most tree species are completely charred by fire, they seldom recover. In southern California, coast live oaks (Quercus agrifolia) resprout from the trunk and upper limbs within three months following a fire. This is technically referred to as epicormic sprouting. It also occurs in some fire-adapted species of Eucalyptus in Australia. The thick, fire-resistant bark of these oaks provides protective heat insulation for the living cambial cells beneath the bark. Compared with other oaks, the relatively smooth-textured bark inhibits the fire from being carried up the trunk. Instead, the flames are gradually extinguished as the bark becomes blackened and charred.

One of the most amazing phenomena in nature's remarkable recovery from fire is the brilliant display of wildflowers that appears with the onset of winter and spring rains. Often the dazzling spectrum of color changes from orange to purple, yellow or blue, as one population of colorful wildflowers gradually fades and is replaced by another. Carpets of golden daisies, baby blue-eyes and white forget-me-nots give way to masses of purple lupines, penstemons and phacelias, mixed with bright orange California poppies. The profusion of blossoms is highlighted by vivid red clumps of Indian paintbrush, crimson campions and scarlet larkspurs. Blackened remains of chaparral thickets are decorated here and there with bright pink wild sweet peas and purple climbing snapdragons. Twining vines of wild cucumber often cover the burned shrubs, with large, spiny green fruits which hang like ornaments from the charred branches. In shady canyons and ravines lovely pink and white Chinese houses resemble a miniature city of tiered oriental pagodas. Many showy wildflowers develop from deep-seated bulbs and corms, often later in spring after the annuals have bloomed and gone to seed. Blue wild hyacinths and pink wild onions make their spring debut, followed by beautiful lilac and golden mariposa lilies.

The scarcity of wildflowers in mature chaparral and their abundance after fire has been studied extensively in recent years. Fires generally occur once in every 10-40 years and seeds of some wildflowers may lie dormant for decades, and then germinate by the millions following fire. Along with spring rains, sunlight and fertile, ashy soil are importantant factors in the profusion of wildflowers. Unfortunately, most of the reseeding campaigns to prevent erosion include introduced mustards and weedy grasses, such as wild oats and rye grass, which compete with and crowd out our colorful native soil binders. Fire breaks down the impervious seed coat of some wildflowers and allows them to imbibe water. Other seeds will still not germinate unless tissue covering the embryonic root within the seed is removed. Heat or other biochemical factors may be involved in breaking dormancy in some seeds. Studies have shown that the burned remains of shrubs greatly stimulate the germination of certain seeds. The developing wildflowers thrive in the ash and often grow much more vigorously than in soil without ash.

Studies conducted by Cornelius H. Muller and his graduate students during the 1970s indicate that terpene chemicals present in the resinous foliage and fallen leaves of chaparral shrubs inhibit germination of wildflower seeds, a phenomenon known as allelopathy. Fire destroys these inhibitory chemicals that have leached into the soil, and explains the abundance of wildflowers in recently burned chaparral. [I have also observed an abundance of wildflowers in areas of unburned chaparral that were cleared for avocado groves.]

Some botanists believe that allelopathy does not adequately explain the paucity of certain wildflower species in unburned coastal sage scrub and chaparral. The classic aerial photo on the cover of Science Vol. 143 (31 January 1964) shows a mosaic pattern of white lines (bare ground "halos") around purple sage (Salvia leucophylla), white sage (S. apiana) and California sagebrush (Artemisia california) in the coastal sage scrub of Santa Ynez Valley northwest of Santa Barbara.

These bare ground patterns were attributed to allelopathy by Cornelius Muller, Walter Muller and Bruce Haines in their article "Volatile Growth Inhibitors Produced by Aromatic Shrubs" (Science 143: 471-473). Later in 1964, Philip Wells argued that these patterns may have been caused by factors other than allelopathy, such as cattle trails (Science 143: 889). In 1970 Bruce Bartholomew published a plausible rodent explanation (Science 170: 1210-1212). Small rodents such as the California mouse (Peromyscus californcus) and Pacific kangaroo rat (Dipodomys agilis) hide from predators under the dense cover of shrubs. They make short forays into the surrounding grassland to nibble on seeds or new growth. They generally do not stray far so they can quickly leap back into the shrub canopy for safety. Bare zones around shrubs can thus be explained as "calculated risk terrain" where rodents have a chance to grab food without getting caught. Herbaceous growth increases significantly in "bare zones" protected from rodents.

One problem with the rodent grazing hypotheses is that grasses grow within bare zones around shrubs during wet years despite animal activity. Why don't rodents always eliminate seedlings? In complex ecosystems such as the chaparral and coastal sage scrub it seems plausible that chemical factors may also be involved; however, chemical hypotheses tested in laboratories may not apply to conditions in natural habitats. Allelopathy has clearly been documented for some plant species and perhaps it cannot be completely ruled out for chaparral and coastal sage scrub plant communities.

The alleopathy controversy has been summarized by Richard W. Halsey in his article "In Search of Allelopathy: An Eco-historical View of the Investigation of Chemical Inhibition in California Coastal Sage Scrub and Chamise Chaparral (Journal of the Torrey Botanical Society 131 (4), 2004, pp. 343-367). According to Halsey (2004): "For chaparral, it is clear innate dormancy in seeds can account for the lack of herbs under the community's canopy. The remarkable post-fire germination cycle can be explained without invoking environmentally induced chemical inhibition. Poor growing conditions under mature shrubs selected for traits postponing germination until those conditions improved, such as after fire, including higher available nutrients levels, more space and light, and lower herbivory." The previous quotation explains the abundance of wildflowers I have observed in recently cleared chaparral designated for avocado groves in San Diego County.

One of the best examples of allelopathy is the spotted knapweed (Centaurea maculosa syn. C. stoebe). This noxious European perennial weed secretes a potent allelopathic flavonoid called catechin from its roots that literally kills neighboring plants. Catechin has two mirror image forms, a positive (+) form and a negative (-) form. The +catechin is an antibiotic and antioxidant that prevents the formation of free radicals. It is present in a number of plants, including green tea (Camellia sinensis). The -catechin induces oxidation and cellular death in root cells of neighboring plants. Although the mechanism is complex, -catechin is a potent phytotoxin that causes plants to self destruct by producing free radicals as well as triggering genes that kill the cells. Cellular death may occur within an hour of exposure to catechin. See the following reference for more details: H.P. Bais, R. Vepachedu, S. Gilroy, R.M. Callaway and J.M. Vivanco. 2003. "Allelopathy and Exotic Plant Invasion: From Molecules and Genes to Species Interactions." Science 301: 1377-1380 (September 5, 2003).

In other species allelopathy has been demonstrated to play an important role in forests, influencing the composition of the vegetation and patterns of forest regeneration. The black walnut (Juglans nigra) produces the phenolic compound juglone, an allelopathic substance that interferes with the growth of certain plants. It has been shown that some plants are inhibited by juglone while others appear to be unaffected. It is well-known that Eucalyptus leaf litter and root exudates are allelopathic for certain soil microbes and plant species. The tree of heaven (Ailanthaus altissima) also produces allelopathic chemicals in its roots that inhibit the growth of many plants. More research may lead to a better understanding of the role of allelopathic substances in natural ecosystems, including California plant communities.

In San Diego County, seedlings of shrubs also appear in the ashy soil after fires, particularly California lilac (Ceanothus tomentosus var. olivaceous), black sage (Salvia mellifera) and chamise (Adenostoma fasciculatum). In fact, Ceanothus tomentosus is a relatively short-lived shrub and periodic brush fires are necessary for its rejuvenation and propagation. The roots of some species of Ceanothus have nodules containing nitrogen-fixing actinomycetes. These are fliamentous, fungus-like bacteria rather than the eubacteria found in the root nodules of legumes.

Several species of California cone-bearing trees, including the knobcone pine (Pinus attenuata) and bishop pine (Pinus muricata) grow in chaparral areas and have fire-adapted serotinous seed cones. These species are able to reseed themselves after fast-moving fires as their tight, woody cone scales slowly open and release seeds on the burned slopes. In fact, without fire the serotinous cones of the knobcone pine may remain closed for the life of the tree. The knobby cones are so firmly attached to the trunks of old trees, that they literally become enveloped by the expanding bark. [Left: Photo of knobcone pine cone cluster.]   See A Knobcone Pine Gear Shift Knob

Without fire, cones of the knobcone pine may remain closed for 80 to 100 years or more. In fact, Mr. Wolffia (the editor of Wayne's Word) once made a gear shift knob out of a cone for his truck. After more than 30 years, the cone is still tightly closed--with its shiny varnish finish. Fire provides the ideal seedling requirements for these shade intolerant conifers, including full sunlight and ashy-mineral soil devoid of leaf litter and debris (known as "duff" in ecological circles). In addition, the fire kills off certain soil fungi that cause a fatal seedling disease known as "damping off."

There are many other cone-bearing trees throughout North America and other continents with serotinous seed cones. For example, in the Rocky Mountains and the Eastern United States are jack pine (P. banksiana), lodgepole pine (P. contorta ssp. latifolia) and Table Mountain pine (P. pungens), three species with woody seed cones that open during a fire. California cypresses (Cupressus) also produce numerous clusters of serotinous cones. Although cypresses are generally killed in a fire, their woody cones reseed the charred hillsides with a new generation of seedlings; however, fires that are too frequent can be disastrous, particularly if the cypress have not had enough time to produce mature seed cones. Throughout California, ten remarkable cypress species (or subspecies depending on the botanist) occur in isolated groves, sometimes referred to as "arboreal islands." The groves often occur in rugged sites and on poor, rocky soils where chaparral shrubs cannot compete as well. Cypresses probably once formed extensive forests in California, but during the past 20 million years, have been gradually replaced by more vigorous chaparral growth. In fact, their isolation into widely separated groves of relatively small populations has undoubtedly led to some of the subtle "racial" differences in cones, bark and foliage characteristics between disjunct populations within the same species, a phenomenon known as genetic drift.

Serotinous cones of cypress trees open following fire and the seeds are scattered on ashy slopes devoid of competing chaparral vegetation. Under optimal conditions of temperature, sunlight and winter rains, the seeds germinate in the mineral-rich soil and a new generation of cypress trees grows from the ashes. Unfortunately, the fire scenario can also be devastating to cypress groves. Fires occurring too frequently over the same area can destroy a grove if they eliminate the young cypresses before they have a chance to produce sufficient seed cones. I have obseved Tecate cypress (Cupressus forbesii) and Cuyamaca cypress (C. stephensonii) 14 years old with mature seed cones. These were small cypress growing in dense thickets. I discussed this issue with botanists Paul Zedler and Jack Reveal and they concluded that the fire interval should be longer than 40 years. Fires as frequent as 25 years could probably lead to their extinction in local areas. See Armstrong, W.P. 1978. "Southern California's Vanishing Cypress." Fremontia 6 (2): 24-29.

Dripping pitch from the trunk of a Douglas fir (Pseudotsuga menzeisii) in northern Montana. Conifers such as this ignite like a torch during a fire storm due to the combustible terpene oleoresins. Abundant resin ducts throughout the trunk and branches of healthy trees is vital to survive freezing winters and to retard the invasion of bark beetle larvae. During prolonged drought conditions, stressed trees produce less resin and are more vulnerable to bark beetles. In fall of 2003, this drought stress was especially evident throughout mountainous areas of southern California where thousands of pines were dying.

Turpentines include a large group of oleoresins from gymnospermous trees. Raw or crude turpentine is essentially the sticky sap or pitch from coniferous trees. In the U.S., raw turpentine is largely derived from southeastern pines, including longleaf pine (Pinus palustris) and slash pine (P. elliotti) grown in large plantations. Crude turpentine is distilled in order to separate the volatile essential oils called "spirits" from the nonvolatile diterpene residue called rosin. Spirits of turpentine are used in thinners and other organic solvents, while rosin is used in the manufacture of varnishes and oil base paints (and for violin bows and baseball pitchers). Oil base paints also contain unsaturated drying oils, such as castor, tung and linseed oils. The settlement of North America was partially due to England's desire to rid herself of dependence on Scandinavian sources of resin, since the pitch was used to caulk ships and waterproof the rigging.

According to N.T. Mirov (The Genus Pinus, Ronald Press, 1967), all species of pines, except two California species, contain terpenes in their turpentines. The exceptional species are P. jeffreyi and P. sabiniana. The turpentines of these latter two species consists almost entirely of an alkane, n-heptane, with a small mixture of fragrant aliphatic aldehydes. The aldehydes produce distinctive odors in bark fissures of jeffrey pine variously described as resembling vanilla extract, butterscotch or pineapple. Pure heptane, distilled from the resin of P. jeffreyi, was used to develop the octane scale for rating petroleum as a motor vehicle fuel. The following account comes from Conifers of California by Ronald M. Lanner (1999): During the Civil War, Union manufacturers of turpentine used pitch from ponderosa pine (P. pondersosa) because southern pine resins (incl. longleaf and slash pines) were not available from the Confederate States. Sometimes pitch from Jeffrey pine containing volatile n-heptane would get into the heated distillation vats and cause an explosion.

An interesting South African conifer (Widdringtonia nodiflora) that grows in dry brushlands of the Cape region is remarkably similar to our California cypresses (Cupressus). Like the serotinous seed cones of cypresses, the woody cones of widdringtonias open during a fire, but unlike our California cypress, widdringtonias also resprout after fire. This is a very unusual fire adaptation for a cone-bearing species. Although they are not conifers, beautiful flowering shrubs of the genus Banksia, a member of the Protea Family (Proteaceae) are well-adapted to wildfires in southwestern Australia. The woody, cone-like seed capsules slowly open during the heat of a fire, releasing hundreds of winged seeds on the ashy landscape. In addition, some species of Banksia resprout from subterranean lignotubers like chaparral shrubs of southern California. Banksias and widdringtonia can be seen in the Palomar College Arboretum.

Ants are valuable research organisms in several disciplines, including social behavior, communication, genetics of caste determination, and robotics studies. Because they are sensitive to microclimate change and are ideal functional measures of ecosystem disturbance, ants have been studied by The U.S. Geological Survey to show the effects of large California wildfires in San Diego and Orange Counties.

Matsuda, Tritia, et al. 2011. "Effects of Large-Scale Wildfires on Ground Foraging Ants (Hymenoptera: Formicidae) in Southern California." Environmental Entomology 40 (2): 204-216. https://academic.oup.com/ee/article/40/2/204/406319

During the past five years I have conducted ant surveys in unburned habitats at the following six locations using pitfall traps. To my surprise I found a number of unexpected species. This is especially true at Daley Ranch, Owens Peak and Twin Oaks Valley:

One interesting conclusion in the above study by Tritia Matsuga and other authors. They found an increase presence of the harvester ant Messor andrei (syn. Veromessor andrei) in burned scrub habitats potentially benefiting the coast horned lizard (Phrynosoma coronatum). Similar results on red harvester ant Pogonomyrmex colonies in burned areas of the Great Basin were reported by J.D. Holbrook, et al. in Rangeland Ecology & Management 69 (6) 2016. During my 5 year ant survey on the unburned slopes of Owens Peak I found a decline in Messor andrei and no horned lizards. This large, black harvester ant is the primary food source for horned lizards on Owens Peak and the adjacent hills of coastal sage scrub.

Harvester ant major worker (Messor andrei) from Daley Ranch. This species also occurs on Owens Peak, but its numbers appear to be decreasing. Some references list this species as Veromessor andrei. It is quite different from our shiny black desert species M. pergandei.

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19. Conclusions

It is difficult to generalize about the beneficial effects of fire because there are so many complex factors involved. The immediate benefits to a new generation of plant life may not be readily apparent to the casual observer. This is especially true at the time of a personal human tragedy when a houseful of happy memories has been reduced to smoldering rubble. Nonetheless, fire plays an integral role in nature's cycle and has been doing so long before people inhabited this region. With sufficient winter and spring rains these barren hillsides will again become veritable wildflower gardens with acres of colorful species. The air will once again be filled with the perfume of sweet-scented blossoms and the sound of busy, foraging bees. Plants have a remarkable tenacity in the face of fire, and through their dormant seeds and underground burls and bulbs, a new generation will gradually colonize the landscape. Perhaps one day we will fully understand the role of fire in the perpetuation of native vegetation, and the miraculous transformation of ashes to wildflowers.

The role of low ground fires and prescribed burning of forested areas by public agencies has been clearly demonstrated. Reducing the growth of understory shrubs prevents an inevitable lightning fire from being carried into the crowns of trees. This is the case in the Sierra San Pedro Martir of Baja Calfornia where fires have burned out of control for countless centuries. The lack of understory shrubs and fire-scarred trunks on old well-spaced jeffrey pines are testimonials that some trees have survived ground fires during the past century. However, fire management of chaparral in heavily populated regions of southern California is another story and the subject of a "heated controversy." This may also be related to climate change by global warming.

Without fire suppression in the Sierra San Pedro Martir, Baja California, periodic ground fires have swept through these forests of Jeffrey pine (Pinus jeffreyi) and created an open parkland devoid of dense understory vegetation. The trees have thick, fire-resistant bark and can survive repeated ground fires. This is essentially the logic behind prescribed (control) burns in Sequoia-Kings Canyon National Parks,

Prescribed (control) burn in Kings Canyon National Park

Natural periodic brush fires vs. fire suppression: Advocates of natural fire and prescribed burning maintain that properly spaced fire intervals will reduce the fuel build up in chaparral areas and lower the intensity of fire. They maintain that the primary cause of large wildfires is unnatural "fuel" build up due to many years of fire suppression efforts. Advocates of fire suppression counter with some interesting data about devastating fires that occurred less than 10 years apart. These fires were carried by invasive weedy plants and grasses that invaded the previously burned areas. Fanned by dry Santa Ana winds, low humidity and high temperatures, the fires swept over previously burned chaparral that did not have time to recover.

Witch Creek Fire of October 2007 looking south toward Escondido.

Fanned by strong Santa Ana winds with gusts up to 60 mph, the fire in the above image swept westward from Witch Creek east of Ramona to Escondido within 8 hours. The fire essentially followed canyons and hillsides along the general route of the San Dieguito River. It jumped across I-15 south of Escondido and moved into the hillsides bordering Lake Hodges. From here it raced through the hills and canyons west of Escondido on its way to the coast. The Witch Creek Fire burned almost 200,000 acres and destroyed about 1500 homes. This devastating fire followed essentially the same path as the previous devastating Cedar Fire of October 2003.

Embers from fires driven by high winds can start fires up to 1.5 miles away from the "front" of the fire. These spot-fires spread in the direction of the wind, and in turn can start new spot fires in whatever direction the wind is blowing. Everytime you hear that a fire "jumped" the I-15 freeway, this process was at work, since the concrete freeway doesn't burn. I-15 is an 8 lane freeway with a width of 400 feet, greater than the length of a football field. One house in Escondido destroyed by the Witch Fire was 2 miles from the nearest blaze, and yet it caught fire and was gutted without warning.

Sunset over Twin Oaks Valley on hot Labor Day weekend 5 Sept 2020 (107° F). Sun appears bright red through dark smoke cloud from raging Japatul Valley Fire in southeast San Diego County.

As Richard Halsey has stated: We need to use proven strategies, such as firesafe zoning, fire resistant construction, and appropriate defensable space. For example, large housing developments in chaparral areas with only one entrance/exit road are a disaster waiting to happen. These housing developments are a hazard to residents and to fire-fighters. In addition, the typical home has eaves that are a perfect trap for airborne embers. Under natural conditions, native chaparral plants are adapted to periodic brush fires; however, population growth, urbanization, vehicle traffic, and the introduction of alien weeds has altered the natural environment in southern California.

A summary of the fire suppression controversy is available at the following URL. It includes numerous references and field studies supporting both points of view:

The Chaparralian, October 23, 2008, Vol. 5, Issue 3, The California Chaparral Institute: "Threats To The Chaparral." Available On-line at the following URL: http://www.californiachaparral.org/images/CHAP_28_Threats_to_the_Chaparral.pdf

More Images From The Witch Creek Fire In San Diego County

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20. References Cited In This Article

Armstrong, W.P. 1978. "Southern California's Vanishing Cypresses." Fremontia 6 (2): 24-29. Bais,H.P., R. Vepachedu, S. Gilroy, R.M. Callaway and J.M. Vivanco. 2003. "Allelopathy and Exotic Plant Invasion: From Molecules and Genes to Species Interactions." Science 301: 1377-1380 (September 5, 2003). Bartholomew, B. 1970. "Bare Zone Between California Shrub and Grassland Communitites: The Role of Animals." Science 170: 1210-1212. Chou, C.H. and C.H. Muller. 1972. "Allelopathic Mechanisms of Arctostaphylos glandulosa var. zacaensis." American Midland Naturalist 88: 324-347. Christensen, N.L. and C.H. Muller. 1975. Effects of Fire on Factors Controlling Plant Growth in Adenostoma Chaparral." Ecological Monographs 45: 29-55. Halsey, R.W. 2005. Fire, Chaparral, and Survival in Southern California. Sunbelt Publications, Inc., PO Box 191126, San Diego, CA. Halsey, R.W. 2004. "An Eco-historical View of the Investigation of Chemical Inhibition in California Coastal Sage Scrub and Chamise Chaparral." Journal of the Torrey Botanical Society 131 (4): 343-367. Hanawalt, R.B. 1971. "Inhibition of Annual Plants by Arctostaphylos," pp. 33-38. In Biochemical Interactions Among Plants. National Academy of Sciences, Washington, D.C. 134 p. Holbrook, J.D. et al. 2016. "Transition of Vegetation States Positively Affects Harvester Ants In The Great Basin, United States." Rangeland Ecology & Management 69 (6): 449-456. Keeley, J.E., et al. 1985. "Role of Allelopathy, Heat, and Charred Wood in the Germination of Chaparral Herbs and Suffrutescents." Journal of Ecology 73: 445-458. Lanner, R.M. 1999. Conifers of California. Cachuma Press, Los Olivos, California. Marco Turco, John T. Abatzoglou, Sixto Herrera, and Ivana Cvijanovic. 2023. "Anthropogenic Climate Change Impacts Exacerbate Summer Forest Fires in California." Edited by James Randerson, University of California, Irvine, CA. June 12, 2023. Article May Be Accessed At: https://doi.org/10.1073/pnas.2213815120 Anthropogenic climate change impacts exacerbate summer forest fires in California Marco Turco, John T. Abatzoglou, Sixto Herrera, and Ivana Cvijanovic. Edited by James Randerson, University of California, Irvine, CA. June 12, 2023 https://doi.org/10.1073/pnas.2213815120 A newly released study by an international group of scientists shows that human-caused weather and climate change is responsible for the increase in California summer forest fires. Matsuda, Tritia, et al. 2011. "Effects of Large-Scale Wildfires on Ground Foraging Ants (Hymenoptera: Formicidae) in Southern California." Environmental Entomology 40 (2): 204-216. https://academic.oup.com/ee/article/40/2/204/406319 Mirov, N.T. 1967. The Genus Pinus. The Ronald Press Company, New York. Muller, C.H. 1966. "The Role of Chemical Inhibition (Allelopathy) in Vegetational Composition." Bulletin of the Torrey Botanical Club 93: 332-351. Muller, C.H., R.B. Hanawalt, and J.K. McPherson. 1968. "Allelopathic Control of Herb Growth in the Fire Cycle of California Chaparral." Bulletin of the Torrey Botanical Club 95: 225-231. Muller, C.H., Muller, W.H. and B.L. Haines. 1964. "Volatile Growth Inhibitors Produced by Aromatic Shrubs." Science 143 (3605): 471-473. Stowe, L.G. 1979. "Allelopathy and its Influence on the Distribution of Plants in an Illinois Old-Field." Journal of Ecology 67 (3): 1065-1085. Wells, P.V. 1964. "Antibiosis As a Factor in Vegetation Patterns." Science 143: 889. Wuerthner, G. (Editor). 2006. "The Wildfire Reader: A Century Of Failed Forest Policy." Foundation For Deep Ecology & Island Press, Sausalito, CA. 429 p.

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