October iy»b FREMONTIA A Journal of the California Native Plant Society FREMONTIA Vol. 14 No. 3 October 1986 Copyright © 1986 California Native Plant Society Phyllis M. Faber, Editor Laurence J. Hyman, Art Director Beth Hansen, Designer MATERIALS FOR PUBLICATION Members and others are invited to submit material for publication in Fremontia and the Bulletin. All time-value material should be addressed to the Bulletin. Fremontia is a journal for laymen about California plants. Technical botanical articles should be directed to other more scholarly journals. Please double-space copy, using wide margins and fresh typewriter ribbon, on 8!/2-by-ll paper, and include name, address, and phone number, and submit two copies of ms. As a general rule, in the interest of consistency, botanical nomenclature will conform to Munz, A California Flora. Please identify each plant referred to by its botanical name and, if there is one, by its common name. Photographs should be black-and-white glossy prints, prefer- ably 8-by-10 size or accompanied by negatives. Authors are urged to submit MS on floppy discs, produced via Wordstar or Multimate soft- ware on an IBM compatible computer. THE COVER: Representing this special Fremontia issue dedicated to California Chaparral, the cover illustrations by Eugenio Sierra Rafols depict chaparral shrubs (center) Rhus ovata and (clockwise from upper left) Ceanothus leucodermis, Heteromeles arbutifolia, Quercus agrifolia and Arctostaphylos glauca. MEMBERSHIP Dues include subscriptions to Fremontia and the Bulletin. Life (Individual/Couple. $450/500 Individual or Library. $18 Supporting................. $50 Student or Retired. .. $12 Household................. $30 Retired Couple......$15 ADDRESSES Memberships; Address Changes; Officers; General Society Inquiries; Conservation Trust Fund: CNPS, 909 12th St., Suite 116, Sacramento, CA 95814. (916) 447-CNPS Fremontia (Editor): Phyllis M. Faber, Editor, 212 Del Casa Drive, Mill Valley, CA 94941. (415) 388-6002 Fremontia (Advertising): Nancy Dale, Rancho Santa Paula #7,500 W. Santa Maria, Santa Paula, CA 93060. (805) 525-6319. Bulletin: Pauleen Broyles, Editor, P.O. Box 763, Paradise, CA 95969-0763 CNPS Botanist, Data Base: Rick York, 909 12th St., Suite 116, Sacra- mento, CA 95814. (916) 324-3816 or (916) 447-CNPS EXECUTIVE COUNCIL President................................Charlice Danielsen Vice President, Administration................Laurie Kiguchi Vice President, Finance.....................R. Arthur Hayler Vice President, Conservation.......................Ken Berg Vice President, Legislation........................Bob Berka Vice President, Rare Plants................James P. Smith, Jr. Vice President, Publications....................Harlan Kessel Legal Advisor................................Scott Fleming Recorder..................................Joanne Kerbavaz Corresponding Secretary.....................Susan Sommers Past President..................................Robert Will DIRECTORS-AT-LARGE Richard Burgess, Jim Dice, Roman Gankin, Jo Kitz, Mary Merryman, Tim Thomas California Native Plant Society Dedicated to the Preservation of the California Native Flora The California Native Plant Society is an organization of laymen and professionals united by an interest in the plants of California. It is open to all. Its principal aims are to preserve the native flora and to add to the knowledge of members and the public at large. It seeks to accomplish the former goal in a number of ways; by monitoring rare and endangered plants throughout the State; by acting to save endan- gered areas through publicity, persuasion, and, on occasion, legal action; by providing expert testimony to governmental bodies; and by supporting financially and otherwise the establishment of native plant preserves. Much of this work is done through CNPS Chapters throughout the State. The Society's educational work includes: pub- lication of a quarterly journal, Fremontia, and a quarterly Bulletin which gives news and announcements of Society events and conser- vation issues. Chapters hold meetings, field trips, and plant and poster sales. Non-members are welcome to attend. The work of the Society is done by volunteers. Money is provided by the dues of members and by funds raised by chapter plant and poster sales. Additional donations, bequests, and memorial gifts from friends of the Society can assist greatly in carrying forward the work of the Society. Dues and donations are tax-deductible. CHAPTER PRESIDENTS (AND DIRECTORS) Bristlecone (Inyo-Mono).........................Ann Yoder Channel Islands..............................Darl Dumont Dorothy King Young (Gualala)...........Florence Vanderwater East San Francisco Bay....................William R. Keeler Kern County................................Diane Mitchell Marin.......................................Sue Hossfeld Milo Baker (Sonoma County)....................Walter Earle Monterey Bay.................................Mary Meyer Mount Lassen.................................Mike Foster Napa......................................Ernest Fremont North Coast................................Bruce Bingham Northern San Joaquin Valley (Modesto)..........John Herrick Orange County...............................Dave Bramlet Riverside/San Bernardino Counties.............Karen Kirtland Sacramento Valley......................Lorraine Van Kekerix San Diego....................................Joan Wilson San Gabriel.................................Harry Spilman Sanhedrin (Ukiah).............................Mark Albert San Luis Obispo............................Gary Ruggerone Santa Clara Valley.............................Bart O'Brien Santa Cruz...............................Adrienne Harrold Santa Monica Mountains.................Linda Hardie-Scott Sequoia (Fresno).............................Jeanne Larson Shasta........................................Jim Mallory South Coast (Palos Verdes)...................Richard Dulzeul Tahoe.........................................Bob Allard Yerba Buena (San Francisco)......................Pat Fallon 2 STRUCTURE AND FUNCTION IN CALIFORNIA CHAPARRAL by Philip W. Rundel The familiar Mediterranean-type climate of Califor- nia is characterized by cool, moist winters and hot, dry summers. Only five regions of the world, including parts of California, have a Mediterranean-type climate. These are the Mediterranean basin of Europe, which extends into Asia, and North Africa, central Chile, the south- western Cape region of South Africa, and parts of southwestern parts of Western and South Australia. All of these regions are middle-latitude belts (about 30 to 40 ° South and North latitude) on the western margins of continental land masses. Chaparral is the most prominent vegetation type within the Mediterranean-type climate region of Cali- fornia. The term chaparral comes from the Spanish chaparro, which originally denoted a cover of shrubby, evergreen oaks. The term now is used broadly to describe dense, evergreen shrublands composed of many different species but with characteristic and remarkable parallels in vegetative form —this chaparral form includes a woody, rigid, branching structure and a dual root system with deep tap roots as well as shallow lateral roots. Chaparral communities are dominated by ever- Sugar bush (Rhus ovata) has thick, heavily-cutinized, leathery leaves, typical of plants in the chaparral community. Illustrations by Eugenio Sierra Rafols. green shrubs with small, sclerophyllous ("hard leaved") leaves, which are thick and heavily cutinized and leather in feel. Similar vegetation occurs in other Mediterra- nean-type ecosystems of the world, the result of conver- gent evolution of morphological form under similar selective pressures. Comparable communities to what we call chaparral in California are termed maquis or gar- rique in southern Europe, matorral in central Chile, fynbos in South Africa, and kwongan or heath in Aus- tralia. It is important to remember that not all Mediterra- nean-climate vegetation is similar to chaparral. In Cal- ifornia, chaparral is only one of a number of major plant associations that occur in this climatic regime. In areas of the state where annual precipitation exceeds about twenty-eight inches, chaparral is replaced by com- munities dominated by conifers or broad-leaved decid- uous species of trees and shrubs, except on serpentine soil. The coniferous forests of the Sierra Nevada and coast redwood zone are floristically unique but are structurally similar to coniferous forests in other parts of the country that lack Mediterranean climates. Where annual precipitation drops below about ten inches, desert vegetation is predominant. Nevertheless, Sono- ran Desert vegetation in the Mediterranean-climate region of California is not dramatically different from that in the summer- and winter-rainfall desert areas of Arizona. • 4 Chaparral vegetation in California occurs in the Coast Ranges and foothills of the Sierra Nevada from southwestern Oregon and Northern California to the mountains of Southern California and northern Baja California. Chaparral covers about three and one-half million hectares or one-twentieth of the total area of the state. In addition to the continuous extension of chap- arral communities along the Sierra San Pedro Martir in northwestern Baja California, outliers of chaparral vegetation occur as far south as the Sierra de la Giganta in southern Baja California and eastward into the summer-rainfall regions of Arizona and northern Mexico. These outliers are thought to be relicts of a more extensive Madro-tertiary geoflora that became iso- lated in the Quatenary with topographic changes and development of a Mediterranean-type climate. Although chaparral vegetation was first described in detail in government forest surveys around the turn of the century, the foundation for our modern ecological understanding of chaparral was laid by William S. Cooper in 1922. Cooper not only described the extent and environmental relationships of chaparral vegeta- tion, but also outlined the importance of fire succession. In addition, he carefully noted the significance of microenvironment on leaf structure and water loss, and surveyed the anatomical features of the leaves of a large number of sclerophyllous species. His work inspired a number of others to study the phenology, microenviron- ment, and water relations of chaparral plants and was the basis for the strong resurgence in chaparral research over the past two decades. Chaparral Communities Mature chaparral is characterized by a coverage of woody evergreen shrubs three to ten feet in height. The predominant chaparral shrub in California is chamise (Adenostoma fasciculatum). Needle-leaved chamise shrubs form the major coverage on dry, south-facing slopes throughout the range of chaparral. Chamise often occurs in pure stands without associated shrub species. This widespread dominance is unique among shrubs in Mediterranean-type ecosystems of the world, where mixed domiance is typical. On north-facing slopes of chaparral, chamise is com- monly replaced by stands of mixed dominance with Cal- ifornia scrub oak (Quercus dumosa) and/or species of manzanita (Arctostaphylos) and Ceanothus. The latter two genera have more than forty species each in Cali- fornia. Other important evergreen chaparral shrubs with widespread distribution include redberry (Rhamnus crocea), sugar bush (Rhus ovata), laurel sumac {Malosma laurina), toyon (Heteromeles arbutifolia), mountain mahogany (Cercocarpus betuloides), and holly-leaved cherry (Prunus ilicifolia). Chaparral communities are not comprised solely of evergreen, woody shrubs, but rather a wide mixture of growth forms are characteristically present. Xeric rocky slopes and ridges, and disturbed sites are commonly dominated by mixed stands of drought-deciduous sub- shrubs with a variety of annual and perennial herbs. Such subshrub and herb communities are an important element of post-fire successional sequences in chaparral. Drought-deciduous communities called coastal sage scrub are closely associated with chaparral areas from central California to northwestern Baja California. In contrast to evergreen chaparral shrubs, the dominant species of coastal sage scrub are lower (one and one-half to five feet tall), less woody, and have soft, mesophytic leaves that are largely lost during periods of summer drought. These characteristics have led to the local name of "soft" chaparral. The characteristic species are Cal- ifornia sagebrush {Artemisia californica), several species of sage (Salvia), Encelia californica, and California buckwheat (Eriogonum fasciculatum). Such evergreen shrubs as lemonadeberry (Rhus integrifolia), laurel sumac, and toyon may also be common. Coastal sage scrub communities occur extensively along lower coastal areas, generally below the eleva- tional belt where evergreen chaparral shrubs predomi- nate. It is generally believed that the length of the summer-drought period in these coastal habitats precludes the success of most evergreen shrubs. It is not surprising, therefore, to find coastal sage scrub in a narrow zone between chaparral and desert or arid grass- lands on the inner side of the Coast Ranges. Coastal sage scrub species do occur in the higher-elevation chap- arral belt, as post-disturbance colonizers or on steep or rocky xeric sites. Fire Ecology Fire is unquestionably the dominant environmental factor influencing chaparral vegetation. Although it is difficult, or impossible, to determine natural frequen- cies of fire in chaparral, speculative guesses have gener- ally ranged from ten to forty years. There are lines of evi- dence, nevertheless, suggesting that these estimates may be on the low side. At least in parts of the range of chap- arral, the demographic patterns of shrub life history and the rarity of lightning strikes suggest longer periods between fires. In considering fire frequencies in chaparral, too much focus can easily be given to mean fire frequencies. Such discussions tend to ignore the significance of the range of variation in fire intervals. Most chaparral stands are able to carry a fire after only a few years of post-fire growth. At the other extreme, there exist large areas of chaparral that have not burned in this century. More than sixty percent of the chaparral areas of Sequoia National Park, for example, have not burned since detailed fire records were begun in 1920. Fire suppression policies during the past century are thought to have significantly reduced the frequencies of chaparral fire and led to increased build-ups of flam- mable biomass. While the effect of increased fire sup- pression must be balanced against the increased fre- quency of man-caused fires, there is no question that catastrophic chaparral fires in many parts of California increasingly threaten lives and property. As a result, the use of prescribed burning under controlled conditions is becoming more commonly used as a management tool. A wider use of prescribed burning, however, has been limited by a lack of detailed knowledge of the fire ecology of chaparral. Studies of the successional dynamics of chaparral vegetation provide an important interface between basic research and effective resource management. Chaparral fires of moderate intensity burn off a major part of the above-ground shrub biomass as well as litter. Blackened stems of the larger shrubs commonly remain standing, although these too may be consumed in a very hot fire. The dominant pre-fire shrubs rapidly recolonize burn sites by reseeding and/or resprouting, but in the first few years following a fire the major cover- age and biomass of the community consists of herba- ceous ephemerals and short-lived subshrubs. The dense stands of ephemerals characterize the first season of post-fire growth. These ephemerals include both "fire annuals," which are often restricted to burn sites, and generalist herbs with broader ecological ranges of occur- rence. The herbaceous composition during the first few years of post-fire succession changes gradually from an initial dominance by native annual and perennial dicots to an increasing importance of exotic grasses in subse- quent years. The diversity of herb species in the first year following a fire is remarkable. Up to twenty-five species or more may be found in a single square meter. Strangely, California is the only one of the five Mediterranean-type ecosystems with such a diverse assemblage of annual fire successional herbs. A variety of short-lived subshrubs germinate the first year following a fire, and these form an important ele- ment of stand structure in the first few years of succes- sion. Good examples of these are Lotus scoparius, Den- dromecon ridiga, and species of Eriodictyon. These commonly become senescent within five to ten years fol- lowing a fire and are replaced in coverage by a rapidly closing canopy of the original pre-fire shrub dominants. There are two principal ways in which chaparral shrubs respond to fire. One group of species, including the majority of chaparral genera, resprouts from under- ground root crowns. This trait appears to be an ances- tral one in vascular plants where it is of adaptive value, not only following fire, but also after damage by frost, drought, or heavy grazing. With one notable exception, species that resprout do not have seeds that are stimu- late to germinate following a fire. The other mode of response to fire is non-sprouting, with reestablishment through germination of seeds. Seed pools in these spe- cies are stimulated to germinate by the heat of the fire (and possibly by chemical effects as well). A group of species within Arctostaphylos and Ceanothus exhibit this trait, but these are distinct subgenera from the resprouting species in the same genera. The one excep- tion to the dichotomy between resprouting and reseed- ing occurs in chamise which utilizes both strategies. While this may be a factor in the ecological success of chamise, it is still very much a mystery why other shrub species have not evolved a similar "bet-hedging" evolu- tionary strategy. There seems to be clear selection against such a strategy in other groups. Resprouting species of chaparral shrubs do not invari- ably survive fire. Fire intensity and seasonality both have profound effects on rates of root crown mortality. Generally, fires in spring or early summer, at a time when carbohydrate reserves of root crowns are depleted by rapid above-ground growth, cause much higher rates of mortality than do late-summer or fall fires. These later times correspond to periods when root carbohy- drate reserves have been restored. Surviving root crowns produce resprouts that have low levels of water stress and high levels of foliar nitrogen. As a result, the photo- synthetic capacity of resprouts is high and growth rates are rapid. Growth Behavior The growth behavior of chaparral plants is strongly tied to the availability of soil moisture. One aspect of this can be seen in the asynchronous growth cycles of different plant growth forms. Many shallow-rooted annuals begin their growth cycles soon after the onset of fall rains. These species reach their peak growth with flowering in late winter or early spring before surface soils dry out. In contrast, some deep-rooted evergreen shrubs do not begin above-ground growth until mid- winter, but often continue some growth into midsum- mer. Drought-deciduous shrubs with roots of intermedi- ate depth have an intermediate timing of growth. Physiological traits such as water relations, photo- synthesis, energy, as well as rooting depth also play an important role in determining patterns of phenological growth. In the southern Sierra Nevada, woodland trees such as blue oak (Quercus douglasii), interior live oak (Q. wislizenii), and California buckeye (Aesculus califor- nica) reach their peak of vegetative growth in March, two months ealier than the peak for adjacent stands of chaparral shrubs. Physiological traits and evolutionary history also act to influence the timing of vegetative and reproductive growth in chaparral shrubs. The three most common shrubs in the chaparral of the southern Sierra Nevada all exhibit different patterns of growth. Whiteleaf manzanita (Arctostaphylos viscida) flowers before vegetative growth takes place, using developing buds formed during the previous season. In buck brush (Ceanothus cuneatus) there are no preformed buds, and vegetative and reproductive growth are simultaneous. In chamise flowering begins after completion of stem growth as the apical meristems form determinate in- florescences. While most chaparral shrubs flower in spring, it is interesting to note that two of the most obvi- ous summer-flowerers, laurel sumac and chamise, in- habit some of the driest chaparral habitats. Water Relations Patterns of water use and drought tolerance vary con- siderably among chaparral species. Depth of rooting is obviously an important consideration in water availabil- ity to chaparral plants. Deep-rooted evergreen sclero- phylls are often considered to be "drought tolerators" because they maintain most of their leaf canopy throughout the summer dry season. This is certainly true of many shrub species that commonly reach water tensions of —5.0 MPa in late summer and as low or lower than -8.5 MPa in drought years. The units of mega Pascals (MPa) indicate the water tension or nega- tive pressure in the xylem column of these plants. The lower the tension the more water the plant can pull from the soil. The more negative numbers indicate lower 6 Toyon (Heteromeles arbutifolia) is an important shrub in the chaparral and is frequently found on north-facing slopes. water tensions and are thus more stressful. A water ten- sion or negative pressure of - 8.5 MPa is equivalent to a pressure of more than 1,200 pounds per square inch, a remarkable example of evolutionary engineering in water-conducting systems. Such low levels of water ten- sion are more severe than those experienced by most desert plants. Drought-deciduous subshrubs and herbaceous spe- cies have commonly been considered "drought avoiders." They shed photosynthetic tissue in response to water strees, and commonly remain dormant through the period of maximum drought. Some annuals weather this period in the form of seeds. Recent research has suggested that physiological differences between "drought tolerators" and "drought avoiders" may not be as great as had been thought. A number of woody shrubs and trees appear to never be subjected to extremely low water potentials. Deep- rooted species of oak, both deciduous and evergreen, fit this category, as do sugarbush, lemonadeberry, and laurel sumac. At the other end of the spectrum, a number of drought-deciduous shrubs are metabolically active at very low water tensions (i.e., high stress levels). A good example of this can be seen in black sage (Salvia mellifera), which exhibits a seasonal dimorphism in leaf morphology, with large and relatively mesophytic leaves with no obvious drought-tolerating characteristics in spring and a limited number of smaller, more sclero- phyllous leaves in summer. Although the few terminal summer leaves represent only a small part of the sea- sonal leaf area of the plants, they are capable of main- taining low levels of net photosynthesis at very low water tensions. While it has not been investigated physiologically, seasonal leaf dimorphism has been observed in a large number of other drought-deciduous subshrubs in Cal- ifornia. Examples include California sage (Artemisia californica), Encelia californica, Isomeris arborea, white sage (Salvia apiana), S. leucophylla, sticky monkey (Diplacus sp.), Eriophyllum confertiflorum, Brickellia californica, and Haplopappus squarrosus. The presence of such dimorphic leaves may be variable within a genus. California buckwheat, with semi-evergreen, sclerophyllus leaves, does not exhibit this characteristic, while Eriogonum cinereum, with more mesophytic leaves, does have seasonal leaf dimorphism. Most of these species with seasonal leaf dimorphism lose all of their leaves (and often much of their above-ground stems) with full levels of summer drought. Only a few species, such as black sage, will maintain some xero- 7 phytic leaves that last all summer into the next growing season. Seasonal leaf dimorphism, also common in drought-deciduous desert shrubs, is thought to be an adaptation to reduce transpirational water loss and min- imize potential drought stress. Suites of morphological, anatomical, and physiolog- ical characteristics often evolve together to provide greater drought tolerance in individual groups of spe- cies. This situation is illustrated in the two subgenera of the genus Ceanothus, subgenera Cerastes and Ceanothus. Both subgenera form evergreen shrubs that are widespread in chaparral. Species of the more drought-tolerant members of the subgenus Cerastes have shallower roots and close their stomata at lower water potentials than do members of the subgenus Ceanothus. The thicker cuticles and leaves, higher leaf densities, presence of sunken stomata, and vessel anat- omy of Cerastes are all consistent with greater drought tolerance. Despite these differences, species of both sub- genera commonly occur together in chaparral stands. Photosynthesis Evergreen chaparral shrubs have the capacity to pho- tosynthesize throughout the year, although at a some- what reduced rate in summer. The sclerophyllous nature of chaparral leaves, however, is associated with low photosynthetic rates in comparison to the leaves of deciduous species. Typically, the maximum rates of photosynthesis for evergreen chaparral leaves is only about half that for drought-deciduous shrubs. The opti- mum temperature for photosynthesis is remarkably broad in chaparral shrubs, with little difference in the range from 45° to 87° F. This suggests that with mild winters in the Mediteranean-climate region of Califor- nia, the principal limiting factor for net photosynthetic gain during the winter months is a short photoperiod rather than low temperatures. Patterns of the allocation of photosynthesis products in chaparral shrubs have been studied in considerable detail. While above-ground growth is commonly limited to a four- to six-month period, net photosynthetic pro- duction occurs throughout the year. In fall and winter, when there is no above-ground growth, this carbon product is allocated to root growth, below-ground car- bohydrate storage, and the development of chemical defenses against herbivores. Nearly two-thirds of the annual photosynthetic budget in evergreen chaparral shrubs goes to maintenance and growth respiration. Root respiration alone accounts for about one-quarter of the annual budget. In comparison to the leaves of deciduous plants, the sclerophyllous leaves of chaparral plants are expensive to produce in terms of physiologic costs. This is because of their high lignin content, which makes them hard, 8 and the common presence of secondary metabolic com- pounds. The metabolic cost of these leaves, however, is amortized over a longer period of useful life than are deciduous leaves. Leaves of most evergreen chaparral shrubs typically last two years. Other nominally ever- green species, such as mountain mahogany (Ceanothus betuloides) and mountain misery (Chamaebatia foliolosa), have individual leaves that last twelve to nine- teen months. Herbivory The leaves of virtually all chaparral plants have vari- ous qualities that may act to reduce herbivory. Some of these are morphological and anatomical characteristics that result from adaptations to their climatic regime. The leathery leaves of most chaparral shrubs, for exam- ple, have high concentrations of undigestible fibers in the form of lignin (and cellulose), low concentrations of nitrogen, and reduced levels of tissue water. All of these certainly reduce the palatability of leaves to her- bivores, but account for little additional energetic cost beyond the features important in physiological tolerance to drought. Most woody chaparral plants, however, allocate sig- nificant portions of their energy resources to the forma- tion of chemical compounds that appear to have no physiological function other than deterring herbivores Chamise (Adenostoma fasciculatum), the predominant shrub of California's chaparral community, forms the major cover on dry, south-facing slopes. or pathogens from feeding on leaves or other plant tis- sues. One of the most important such compounds is tannin. Up to twenty percent of the dry weight of leaf tissues in some shrubs may be composed of tannins. Species of oak, manzanita, and toyon are all character- ized by tannin-rich leaf tissues. The ecological sig- nificance of tannins is thought to lie in their ability to bind proteins to form non-biodegradable products. This is exactly the principle used in the tanning industry, where animal skins are treated with tannins extracted from plant tissues. The tannins form complexes with the collagens of the hides to produce leather, a highly stable product. When herbivores attempt to feed on leaves rich in tannins, these chemicals are released from vacuoles and form undigestible complexes with many of the pro- teins present in the cytoplasm. The result is a poor food for herbivores, since nitrogen (in the form of proteins) is their most important food resource. Tannins may also form complexes with the digestive enzymes of herbi- vores, thereby reducing their ability to digest food from leaves consumed. Young leaves, which have high protein concentrations, often have the highest levels of tannins. Another interesting group of compounds present in leaves of toyon, the cyanogenic glucosides, may protect this species from both herbivores and pathogens. Under normal conditions, a chemical complex of cyanide and sugar in the leaves forms a harmless compound. When hydrolytic enzymes are released as leaves are damaged, the resulting chemical reaction cleaves off the sugar por- tion of the molecule and releases highly toxic hydrogen cyanide gas. This process is a highly efficient system of protection since the hydrogen cyanide is released only if the plant is damaged. Cyanogenic glucosides have been studied intensively in herbaceous species of Trifo- lium, Lotus, and acacia, where they provide an impor- tant factor in minimizing herbivory by snails and slugs. Often there is an ecological trade-off for a plant between maximizing potential growth and minimizing tissue loss to herbivory. Yerba buena (Satureja douglasii), a herbaceous perennial from the coastal chaparral and woodlands of central California, provides an example. Mesic shade populations of this species grow successfully but do not have sufficient reserves of photosynthetic product to form high concentrations of terpenoids, and as a result they are heavily browsed by banana slugs. Populations growing in sunny habitats are more successful, despite the xeric nature of such habitats, because they are able to allocate photosynthate to accumulate terpenoids and thus deter herbivores. An analogous situation can be seen with phenolic resins on the leaf surfaces of shrubby species of Dipla- cus. From fifteen to thirty percent of the dry weight of their leaves is comprised of these sticky resins, which are important in determining herbivory by butterfly larvae. These herbivores appear to cue in on leaves with the most favorable nitrogen-to-resin ratio. Generally, plants with high leaf nitrogen contents (those potentially providing the best herbivore food resource) have high photosynthetic capacities and are able to allocate suffi- cient photosynthate to resin production to effectively deter herbivory. Plants with low leaf nitrogen contents have low photosynthetic capacities and are thus poorly defended by resins but offer a nutritionally marginal food resource. High concentrations of similar pheno- lic resins are present in other chaparral shrubs, for exam- ple, species of yerba santa and mountain misery and are likely to play comparable roles. There are many examples of other types of chemical compounds in chaparral plants that may also play important roles in restricting herbivory. Many of us have experienced the effectiveness of phenolic compounds in poison oak called resorcinols. Lemonadeberry, sugar- bush, and laurel sumac all contain related compounds called catechols, which may also cause dermatitis in highly sensitive individuals. Pungent terpenoids are characteristic of many groups of coastal sage scrub spe- cies, particularly members of the mint and sunflower families. Most legumes have either highly toxic alkaloids or similarly toxic non-protein amino acids. All of these compounds, produced at a significant metabolic rate, are thought to reduce potential herbivory and related damage by pathogens. Nutrient Balance Chaparral soils are typically nutrient-deficient, par- ticularly in nitrogen. It is not surprising, therefore, to find a number of chaparral shrubs that have evolved nitrogen-fixing symbioses. Species of Ceanothus and the legume Lotus scoparius are important nitrogen- fixers in post-fire successional sequences in chaparral. Levels of nitrogen fixation by Ceanothus in chaparral appear to be low compared to rates for this genus in the Pacific Northwest. While this limitation was once thought to be due largely to the effects of water stress, there is evidence now to suggest that phosphorus limi- tations may be more important. Phosphorus availabil- ity is a critical element of the fixation process. Other nitrogen-fixing shrubs in chaparral include species of mountain mahogany and mountain misery and chap- arral pea (Pickeringia montana). Chaparral fires cause major losses of nitrogen from these ecosystems due to volatilization of nitrogenous compounds in plant tissues and soil organic matter. Commonly, a moderate-intensity chaparral fire would lead to a direct loss of 133 to 178 pounds per acre. Sub- sequent erosion and leaching of ash add to this loss. Normal atmospheric inputs of nitrogen in dry or wet forms are only a few pounds per ten thousand square miles per year, much too slow to allow replenishment of the pre-fire levels of system nitrogen. Symbiotic nitro- 9 gen fixation by shrubs and herbaceous legumes is the critical element in restoring nitrogen pools in the early years following a fire. Without such symbiotic fixation, the productivity of chaparral stands would steadily decline with each fire. Although fires reduce the total amount of nitrogen in chaparral ecosystems, availability of the inorganic forms of nitrogen that plants can use directly is increased. As a result, post-fire conditions for growth are generally favorable. Concentrations of both nitro- gen and phosphorus in the leaves of resprouts are gener- ally higher for the first few years after a fire, suggesting a "luxury consumption" of these nutrients. Ephemeral herbs represent a larger pool of nutrients in the first year of post-fire growth than do resprouts or seedlings of chaparral shrubs. Thus these herbs play a significant ecosystem role in temporarily immobilizing limiting nutrients that might otherwise be lost through erosion or leaching. While ephemeral herbs maintain a large biomass for several years after a fire, their importance as nutrient sinks steadily declines after the first year. Increasing levels of gaseous and particulate pollutants containing nitrogen are now present in many parts of California. Dry and wet deposition of these pollutants into chaparral ecosystems is clearly causing greatly enhanced levels of nitrogenous inputs to these systems. In the mountains near Los Angeles, such inputs are esti- mated to be ten times or more the natural levels. Such continued inputs, along with physiological responses of chaparral shrubs to oxidant pollutants, will undoubt- edly have profound effects on the structure and stabil- ity of chaparral ecosystems. References Axelrod, D.J. 1958. "Evolution of Madro-Tertiary geoflora." Botanical Review 24:433-509. Conrad, C.E. and W.C. Oechel. 1982. Dynamics and manage- ment of Mediterranean-type ecosystems. USDA Forest Service Gen. Tech. Report PSW-58. di Castri, E, D.W. Goodall, and R.L. Specht (eds.). 1981. Mediterranean-type shrublands. Elsevier Scientific, Amsterdam. di Castri, F. and H.A. Mooney (eds.). 1973. Mediterranean- type ecosystems— origin and structure. Springer- Verlag, Heidelberg. Kruger, F.J., D.T. Mitchell, and J.U.M. Jarvis (eds.). 1982. Mediterranean-type ecosystems— the role of nutrients. Springer-Verlag, Heidelberg. Miller, P.C. (ed.). 1981. Resource use by chaparral and mator- ral. Springer-Verlag, Heidelberg. Mooney, H.A. (ed.). 1977. Convergent evolution in Chile and California. Mediterranean climate ecosystems. Dowden, Hutchinson, and Ross, Stroudsburg, Penn. Mooney, H.A. and C.E. Conrad. 1977. Proceedings of the symposium on the environmental consequences of fire and fuel management. USDA Forest Service, Gen. Tech. Report WO-3. Coast live oak. Quercus agrifolia. 10 t,>i > ¦i;v ¦ ¦ u 0.02 mm A cross-section through a fine root of scrub oak seen with the SEM, X700. Photographs by the authors. MYCORRHIZAL ASSOCIATIONS IN CHAPARRAL by Jochen Kummerow and Wayne Borth Mycorrhizal associations in chaparral shrubs are apparently common, although systematic work is needed to establish the mycorrhizal nature of the fungal infections of fine roots in more shrub species. It is prob- able that mycorrhizae enhance the capacity for mineral nutrient uptake, although no direct observations have been made with chaparral shrubs. This would be espe- cially important in the chaparral, where phosphorus, a growth-limiting element with low mobility in the soil, is frequently in short supply or inaccessible because of extended drought. Current investigations indicate that in scrub oak seedlings mycorrhizal associations can aid in more rapid recovery from drought stress. This could be important for shrub seedling establishment in chap- arral. Numerous studies have been undertaken to demon- strate the biological importance of these associations between plants and fungi. Several recent general reviews are informative about mycorrhizae and their biological significance (Gerdemann, 1975; Smith, 1980; Moose et al, 1981). However, not all ecosystems have been stud- ied in this respect with the same intensity. For example, the mycorrhizae of softwood and hardwood forests in temperate climates have received much attention; un- doubtedly this interest has been stimulated by the eco- nomic importance of these forests. Other areas, such as Mediterranean-type ecosystems with their characteris- tic shrub vegetation, have received much less attention. One recent review reported that mycorrhizae were pres- ent in ninety-two of 106 observed genera in Mediterra- nean shrublands of South Africa and Western Austra- lia (Lamont, 1982). Here we discuss the biological significance of mycorrhizal associations in the chapar- ral of Southern California. 11 Fine roots of scrub oak seen with a scanning electron microscope (SEM), x 200. The roots are covered by a sheath of mycorrhizal fungal hyphae. A Brief Morphology The different types of mycorrhizae, including a vesicular-arbuscular mycorrhizae (VAM), sheathing ectomycorrhizae, and ericoid mycorrhizae can be distin- guished by their morphological features. The differences between these types have been discussed in detail by Harley and Smith (1983). The VAM are present in nearly all land plant families and have been identified in 300 million year old fossils of early land plants. Fungal hyphae are found both intracellularly and intercellularly in the cortex of the fine roots, but only rarely close to the vascular cylinder and the meristem. The most characteristic features of VAM include arbuscules and vesicles. Arbuscules are intra- cellular hyphae with frequently branched distal ends. Vesicles are bulbous, thick-walled structures thought to be important in nutrient storage. Arbuscules and vesi- cles enhance the efficiency of nutrient transfer between hyphae and host cells. The ectomycorrhizae (sheathing mycorrhizae) are characteristic of many woody plant families, including Myrtaceae, Fagaceae, and Pinaceae. They are intercel- lular and do not penetrate into the host root deeper than the endodermis. These mycorrhizae form dense hyphal sheaths or mantles of thirty to forty micrometers in thickness around the host rootlets. Fungal strands may also penetrate deep into surrounding soils. The hyphae of the so-called ericoid mycorrhizae penetrate into the root cortex but also form a sheath of hyphae around the rootlets as described for the ectomycorrhizae. Mycorrhizae in Chaparral A recent survey indicated abundant fungal hyphae were associated with the roots of several chaparral shrub species (Hoelzle, 1983). The observation that the erica- ceous manzanita, Arctostaphylos pungens, had abun- dant mycorrhizal hyphae was not surprising. Ericoid mycorrhizae are consistently associated with members of the Ericaceae; however, in two members of the rose family, the dominant chamise (Adenostoma fascicula- tum) and the locally important red shank {A. sparsifo- lium), the roots have abundant hyphae on rootlet sur- faces and in the cortex. Characteristic vesicles and arbuscules could not be found; thus it would be prema- ture to refer to these shrubs as VAM plants (Hoelzle, 1983). The fine roots of scrub oak (Quercus dumosa), however, show the thick mantle of ectomycorrhizal hyphae characteristic of the oaks in general. In contrast, non-mycorrhizal fine roots had no hyphae on their sur- face and showed the characteristic root hairs that are missing in roots with hyphal sheaths. Fine root of scrub oak seen with the SEM, x200. The root is not covered by fungal hyphae but shows root hairs a short distance from the root tip. 12 Mycorrhizae and Nutrient Uptake The role of mycorrhizae in natural ecosystems is dif- ficult to assess. Few quantitative data are available about the degree of infection within a plant community and the extent of infection of single plants (St. John and Coleman, 1983). It has become increasingly accepted that the hyphae of mycorrhizal fungi transfer soluble nutrients that are otherwise inaccessible to roots and root hairs (Lamont, 1982). This is especially the case with phosphorus, which has a low mobility in the soil solution. Certainly, phosphorus uptake by the fungal hyphae is of benefit to the host plant and assumes trans- fer of the element into host cells, a process that has been shown to occur. Since growth of chaparral shrubs is fre- quently phosphorus-limited, this mechanism might be of considerable importance to chaparral growth. The extension of mycorrhizal hyphae from the sup- porting fine roots into the surrounding soil may reach 2.7 inches (70 mm.), although the actual zone of phos- phorus depletion around a mycorrhizal root may not be greater than 0.2 inches (5 mm.) (Owusa-Bennoah and Wild, 1979). This is significantly more than the 0.08 to 0.12 inch (2 to 3 mm.) depletion zone of a non- mycorrhizal rootlet with root hairs. In addition, there is good evidence that mycorrhizal roots receive phos- phorus at a much higher rate than non-mycorrhizal roots (Sanders and Tinker, 1973). Water Relations of Mycorrhizal Plants There is some evidence to indicate that VAM and ectotrophic mycorrhizae enhance recovery from wilting (Safir, et al., 1972). Preliminary results of an experiment designed to test the effect of mycorrhizal associations on the water balance in scrub oak seedlings support this observation. Surface-sterilized acorns were germinated and cultivated in vapor-sterilized chaparral soil. These seedlings were exposed to increasing water stress by reducing irrigation frequency. Their rate of recovery from stress was compared with that of seedlings from the same origin but grown in unsterilized soil. Microscopic examination confirmed that the seedlings grown in unsterilized soil had indeed developed abun- dant mycorrhizal roots. Stress recovery of the mycor- rhizal seedlings was more rapid than that of the non- mycorrhizal control seedlings. Seedling establishment in chaparral is often limited by low soil moisture (Kummerow, et al, 1985). Because the contact surface between hyphae and soil surface and volume is increased, mycorrhizal associations may play an important role in vegetation recovery after chapar- ral fires. Penetration of heat into the soil from chapar- ral fires varies with fuel and wind speed and ranges from 0.8 to 2.4 inches with temperatures up to 112° F. Hypha Cross-section through a fine root of scrub oak seen with the SEM, x400. The epidermis shows root hairs instead of fungal hyphae. and roots of resprouting shrubs penetrate the soil to deeper levels and are thus insulated from the heat. References Gerdemann, J.W. 1975. "Vesicular-arbuscular mycorrhizae." In J.G. Torrey and D.T. Clarkson (eds.), The develop- ment and function of roots. Academic Press, London, pp. 575-91. Harley, J.L. and S.E. Smith. 1983. Mycorrhizal symbiosis. Academic Press, London. Hoelzle, I. 1983. "Fungal root associations in the Southern California chaparral." M. S. thesis, San Diego State University, San Diego, Calif. Kummerow, I, B.A. Ellis, and J.N. Mills. 1985. "Post-fire seed- ling establishment of Adenostoma fasciculatum and Ceanothus greggii in Southern California chaparral." Madrono 32:148-57. Lamont, B. 1982. "Mechanisms for enhancing nutrient uptake in plants with particular reference to Mediterranean South Africa and Western Australia." Bot. Rev. 48:597-689. Mosse, B., D.P. Stribley, and F. Letacon. 1981. "Ecology of mycorrhizae and mycorrhizal fungi." Adv. Microb. Ecol. 5:137-210. Owusa-Bennoah, E. and A. Wild. 1979. "Autoradiography of the depletion zone of phosphate around onion roots in the presence of vesicular-arbuscular mycorrhizae." New Phytol. 82:133-140. Safir, G.R., J.S. Boyer, and J.W. Gerdemann. 1972. "Nutrient status and mycorrhizal enhancement of water transport in soybean." Plant Physiol. 49:700-03. Sanders, RE. and P.B. Tinker. 1973. "Phosphate flow into mycorrhizal roots." Pesticide Sci. 4:385-95. Smith, S.S.E. 1980. "Mycorrhizas of autotrophic higher plants." Biol. Rev. Cambridge Philos. Soc. 55:475-570. St. John, T.V. and D.C. Coleman. 1983. [["The role of mycor- rhizae in plant ecology." Can. J. of Bot. 61:1005-14. 13 CLOSED-CONE CONIFERS OF THE CHAPARRAL by Paul H. Zedler Closed-cone conifers are distinctive elements of the California flora, and especially in Southern California they are often found in association with chaparral. The unifying character in this grouping of trees is the closed or serotinous (delayed opening) cone, which retains seeds for a year or more after the cones and seeds have matured. Cone opening is erratic, extremely slow, or almost negligible except when the co.nes are exposed to extreme heat, after which it is rapid and uniform. What- ever the evolutionary origin of this trait, it confers on the species that possess it an ability to persist in situa- tions where intense crown fires recur at intervals of a generation or less. This in part explains the success of these trees in co-existing with fire-prone chaparral. According to Vogl et al. (1977), fourteen taxa of Cal- ifornia conifers are definitely closed-cone in all or part of their range — the ten species of cypress native to Cal- ifornia and the four species of pines: bishop pine (Pinus muricata), knobcone pine {P. attenuata), Monterey pine (P. radiata), and pygmy pine (P. contorta subsp. bolan- deri). Beach pine (P. contorta subsp. contorta) is also considered to have closed cones. Three other pine spe- cies often found in or near chaparral —Torrey pine (P. torreyana), Coulter pine (P. coulteri), and digger pine (P. sabiniana) — do not qualify as closed-cone species under the strict definition, but do have delayed seed dispersal which makes them functionally similar. The big-tree Bishop pine cones before fire. Note the stout, sharply pointed appendages that suggest predator deterrence. Photographs by the author. (Sequoiadendron giganteum) also has closed-cone ten- dencies (Harvey, et ai, 1980). Closed-cone conifers are usually found in dense, woody vegetation, sometimes with other tree species, but typically in nearly pure stands or scattered in a matrix of shrubs. The populations of most species occur as clusters of generally well-delimited groves often sepa- rated by tens or hundreds of kilometers. This island-like distribution of closed-cone conifers can be partly explained by soil and geology. Almost without excep- tion, closed-cone conifer stands are on infertile or other- wise chemically inhospitable soils (Vogl, et ai, 1977). The clearest examples of this are Cupressus sargentii and C. macnabiana, which grow only on serpentine noted for the sparse or stunted growth it supports (McMillan, 1956; Kruckeberg, 1984). Other closed-cone conifers are not so restricted, but they almost always occur on sub- strates of below-average fertility, for example, stabilized dunes, sandstone, acid diatomaceous shale, mafic gabbro, and acid volcanic or metavolcanic rocks. Trees or Shrubs? How one views the distribution of closed-cone conifers with respect to climate depends on whether they are considered to be large shrubs or small trees. As trees, closed-cone conifers occur on the dry end of the climate gradient, at sites and on substrates where severe drought occurs at least occasionally. The climatic or edaphic dry- ness prevents the growth of other trees and provides the opportunity for the drought-tolerant closed-cone con- ifer to thrive. Thus in many locations, especially in Southern California, shrubs rather than trees are their most common associates. Closed-cone conifers could also, with some justice, be considered large shrubs that occur where drought is to some degree ameliorated. Several species, for exam- ple Monterey pine and cypress, are found only along the immediate coast on headlands, terraces, or bluffs exposed to the full influence of the ocean. In some sit- uations, such as that of knobcone pine in the Santa Ana Mountains, fog-drip may be vital to their survival (Vogl, 1973). Closed-cone conifers at more inland sites tend to occur on north exposures, deeper canyons, or at higher elevations. We can choose between thinking of closed- cone conifers as medium-sized to giant shrubs occupy- ing less dry sites or dwarf to medium-sized trees occupy- ing the dry fringes of forest habitat. Why Are Cones Closed? Obvious questions about these species are why do they have closed cones, and why does California have more closed-cone conifers than any other area of North America? Closed-cone species are also present in every forested region from the Rocky Mountains (lodgepole pine, Pinus contorta) to the upper Mid-West and Canada (jack pine, P. banksiana) to New Jersey (pitch pine, P. rigida) and Florida (sand pine, P. clausa). Even black spruce in the boreal forest has closed-cone tendencies. Looking further afield, we find that the retention of seed in closed structures is common in South Africa (e.g., Protea spp.) and Australia (e.g., Eucalyptus, Hakea, and Banksia). A common featured shared by these diverse regions is the occurrence of intense crown fires that cause high mortality of woody plants. This is the most convincing evidence to date suggesting that fire is the major factor to explain the closed-cone structure. Field observations after fire in stands of closed-cone species support the hypothesis that the closed-cone trait evolved in response to fire. In closed-cone pines and cypresses, for example, a fire typically causes complete mortality. But if the trees are large and old enough to have produced cones, the heat of the fire stimulates opening of the cones. In pines the resin cementing the cone scales together melts, allowing them to open; in cypresses there is dehydration and resin loss. Most of the seed falls in the first months after the fire, and if the accumulated cone crop is large enough the first rains can produce a remarkably dense and uniform establishment of seedlings. Thus the destruction of one generation of closed-cone conifer sets the stage for the reoccupancy of the site by the next. In the context of the life history of chaparral plants, the closed-cone conifers are therefore "obligate seeders" or seeding non-sprouters, to use the term of Zedler et al. (1983). In California, however, the closed-cone conifers are the only seeding non-sprouters to have canopy storage of seeds. In all other cases (e.g., Ceanothus, Arctostaphylos), the seeds survive in or on the soil. If soil storage of seeds is so obviously successful for chaparral shrubs, why is canopy storage present at all, and why is it also common in South Africa and Austra- lia? Nutrient deficiency may be part of the explanation. Both South Africa and Australia have large areas of nutrient-deficient soils, and it is there that the canopy storage species reach their greatest importance. In the same way, it is primarily on nutrient-deficient sites in California that canopy storage of seeds by non- sprouting seeders is to be found. It seems possible that nutrient deficiency makes canopy storage beneficial by allowing plants to produce fewer seeds with a higher probability of successful establishment because of the timed release that coincides with optimal conditions for establishment. Seeds are concentrated packets of nutrients and energy and are therefore high in phos- phorus, whereas the structures protecting them are woody and therefore low in nutrients. If producing a larger, more protective fruit that releases seeds at the optimal time means that fewer seeds must be formed, the plant could conserve a scarce nutrient, probably phosphorus, at the expense of cheaper carbohydrate. Serotiny, or delayed seed dispersal, also has the advan- tage of averaging out good and bad years of seed pro- duction (McMaster and Zedler, 1981). The benefit of this may be greater on sites where seed production is nutrient-limited. William Bond of the University of California, Los Angeles, has suggested a more parsimonious evolution- ary explanation. A persistent soil seed bank is impossi- ble without an appropriate dormancy mechanism and seeds resistant to decay and protected against predation. Although some conifers have quite hard seeds, none approach the extremes seen in angiosperms. Prolonged dormancy is almost unknown. Thus the option to develop a persistent soil seed bank may not be open to conifers because of the lack of hard seed, an evolution- ary constraint. If this is the case, the angiosperm spe- cies of Australia and South Africa with stored seeds and fire-stimulated dispersal should also be from lineages in which hard-seededness is not present. Under this hypothesis nutrient deficiency may be important primarily because it causes vegetation structure con- ducive to crown fires. Perhaps the closed-cone conifers came to be as they are today by the following route. In the dim past (per- haps early Tertiary) the progenitors of the closed-cone conifers may have first become specialized for nutrient- deficient sites, possibly because competitive pressure from angiosperms excluded a greater proportion of their populations from more productive sites. Uniform canopy height and low stature probably characterized such sites, and exposed the species to the intense selec- tive pressure of fire. In this situation the evolution toward a closed cone may have been rapid. Correlation With Fire If fire is a strong selective force, one would expect to find variation in degree of serotiny (delayed ripening) correlated with fire regime. When fires occur less relia- bly or where fire size is smaller, open-cone individuals are no longer at a severe disadvantage. If fire ceases to be a factor at all, strongly closed-cone individuals would perhaps have a slight chance of establishing offspring, but their success would be minimal compared to any open-cone individuals in the same habitat. Outside Cal- ifornia the expected decrease in expression of serotiny with decreasing probability of fire has been reported for 15 at least two closed-cone conifers, Pinus contorta (Lotan, 1968) and P. rigida (Givnish, 1981). In California such clear patterns have not been demonstrated. There are, however, large differences among species in degree of serotiny. In some, most notably knobcone pine, the closed-cone trait is very strongly expressed. Monterey pine, closely related to knobcone, has cones that remain closed for a few years but often open on the trees on very hot days. Most trees bear many open cones in addition to the generally younger closed cones. In the Bishop pine complex (P. remorata plus the various forms of P. muricata) there is considerable variation in cone mor- phology and the tendency to open. Northern popula- tions are scarcely closed-cone at all, while some south- ern populations of P. remorata are similar to Monterey pine, and others have cones with as little tendency to. open as knobcone pine. In Tecate cypress the cones are strongly serotinous, opening only gradually and largely ineffectively after ten or more years. Stands of this species are made up of even-aged trees. In Monterey cypress serotiny is less pro- nounced, with cones appearing to open two to three years after maturity. Saplings and seedlings may be found scattered under mature trees. The San Pedro Martir cypress, located in the high mountains of north- central Baja California has no serotiny whatever, the cones opening as soon as the seeds are mature (G. Scheid, in prep.). It is difficult to explain this pattern except by fire regime. All three of these species are exposed to fire, but the San Pedro Martir cypress occurs in rocky areas where brush and tree cover is open and extensive crown fires cannot develop. The fires scar the trees but don't kill them, and seedlings and saplings establish at regular intervals, probably without respect to fire (Scheid, in prep.). Tecate cypress occurs in areas where brush cover is extensive and the probability of 16 large crown fires is high, and serotiny accordingly is strongly developed. Monterey cypress, though poten- tially subject to intense fire, occupies headlands on which fires have probably been infrequent. The case of the delayed-dispersing pines is relevant to the question of fire frequency and intensity, as these affect serotiny. Torrey pine (McMaster and Zedler, 1981), Coulter pine (Borchert, 1985), and Digger pine (J. Griffin, pers. comm.) all have cones that generally open at maturity, and thus are not closed-cone pines in the strict sense. However, all retain some seeds in the heavy cones, and studies have shown that seeds thus protected can survive in a viable state for several to many years (McMaster and Zedler, 1981; Borchert, 1985). These spe- cies appear to be playing it both ways, releasing some seeds at maturity to establish if they can, but reserving a portion for release in the event of a crown fire. In Torrey pine, the establishment of seedlings from stored seeds released by fire-killed trees has been confirmed both for wildfire (McMaster, 1980) and controlled-burn situations (Zedler, Scheidlinger, and Scheid, unpubl. data). Borchert (1985) cites studies that document a similar response for Coulter pine, and in his own work has shown that populations of Coulter pine vary in the degree of serotiny expressed. He feels that to a large degree this variation can be explained by between-site differences in fire regime. The closed-cone tendency is less well expressed where fires are likely to be less fre- quent or less intense. Animal Predation and Climate Not everyone agrees about the overriding importance of fire in the evolution of closed-cone conifers. Linhart (1978) has suggested that animals, as well as fire, may have played a role in the evolution of the cone mor- phology of closed-cone pines. Although the thickness and mass of cones may be explained by the heat protec- tion these provide, the massive spines of knobcone and some Bishop pine populations suggest predator deter- rence. Linhart argues that cones of trees most subject to squirrel predation also have the most strongly armed cones. What is unquestionably true is that the closed- cone life history would be an utter failure if the seeds could not be protected against predators. Axelrod (1980), on the basis of historical data, rejects both fire and squirrels as significant influences on cone morphology. He argues that climate, and particularly descreasing summer rainfall, has had the greatest influence on the cones. This hypothesis merits consider- ation. Cone morphology may not be closely linked to serotiny. The closed cone may have begun its evolution as an open cone and made only minor adjustments to serotiny after the basic form had already been deter- mined by other factors. Traits that make a good open cone in a Mediterranean climate may also allow it to shift to serotiny when subjected to intense selection by fire. But evidence from study of cypress seems to con- tradict this theory. Scheid (in prep.) has compared seroti- nal cones of Tecate cypress with non-serotinal cones of the San Pedro Martir cypress and found distinct differ- ences in several traits, with the serotinal cones tending to be woodier. In pines, Muir and Lotan (1985) found in Montana a tendency for the closed cones of lodge- pole pine to have fewer seeds per cone and more cone tissue per seed, suggesting that the open-cone trees had more, but less well-protected, seeds. In general, it would be surprising if strong serotiny did not bring about marked changes in cone morphology that decrease the loss of seeds prior to dispersal. It is hard to see how this could be accomplished except by increasing the mass of the cone, which would simultaneously deter predators and moderate temperature and moisture extremes within the cone. It is difficult to accept Axelrod's argument that the importance of fire in closed-cone conifer evolution has been overemphasized. If, as he asserts, the basic mor- phology of the closed cone was fixed in at least some species millions of years ago, it is reasonable to assume that this was because fire was then, as now, a significant factor. The worldwide pattern for serotiny and canopy storage of seeds shows that these features are neither unique to conifers nor confined to Mediterranean cli- mates. For example, there is a scrub vegetation with many species with canopy seed storage ([Hakea, Bank- sia, Xanthomelum) on nutrient-deficient soils on the coast of subtropical Queensland, Australia. This is an area that receives over 1,400 mm. of rain, mostly in summer. Pockets of tropical rain forest occur in the same landscape. Perhaps serotiny developed in closed- cone conifers of the New World in similar situations in the Tertiary. The overall conclusion is that the explana- tion for California's rich complement of closed-cone species involves climatic history, geology and geo- morphology, and ecological factors with a residue of chance that will probably never be explained. But what- ever the explanation, it cannot fail to consider the ob- viously potent selective pressure of fire. References Axelrod, D.I. 1980. History of the maritime closed-cone pines, Alta and Baja California. University of California Publications in Geological Sciences. Vol. 120, pp. 143. Borchert, M. 1985. "Serotiny and cone-habit variation in populations of Pinus coulteri (Pinaceae) in the south- ern Coast Ranges of California." Madrono, 32:29-48. Givnish, T.J. 1981. "Serotiny, geography, and fire in the Pine Barrens of New Jersey." Evolution, 35:101-23. Harvey, H.T., H.S. Shellhammer, and R.E. Stecker. 1980. Giant sequoia ecology. U.S. Department of the Interior. National Park Service. Washington, D.C. p. 182. Kruckeberg, A.R. 1984. California serpentines: flora, vegeta- tion, geology, soils, and management problems. University of California Publications in Botany. Vol. 78. University of California Press. Berkeley, p. 180. Linhart, Y. 1978. "Maintenance of variation in cone morphol- ogy in California closed-cone pines: the roles of fire, squirrels and seed output." Southwest Nat. 23:29-40. Lotan, J.E. 1968. "Cone serotiny of lodgepole pine near Island Park, Idaho. U.S. Forest Service Res. Paper INT-52. McMaster, G.S. and PH. Zedler. 1981. "Delayed seed disper- sal in Pinus torreyana (Torrey pine)." Oecologia (Berl.) 51:62-66. McMillan, C. 1956. "The edaphic restriction of Cupressus and Pinus in the Coast Ranges of Central California." Ecol. Mono. 26:177-212. Muir, P.S. and J.E. Lotan. 1985. ["Serotiny and life history of Pinus contorta van latifolia." Can. Botany 63:9938-45. Vogl, R.J. 1973. "Ecology of knobcone pine in the Santa Ana Mountains." Ecol. Mono. 43:125-43. Sandy heath in Cooloola National Park in subtropical Queensland, Australia. Despite rainfall high enough to support pockets of tropical forest with palms and strangler figs in the same area, the heath in the foreground contains serotinal Banksia and Hakea species. Other serotinous genera are also present. *&# 17 ** $Hf s f- ;, $.-¦ m Grassland/shrubland mosaic resulting from frequent wildfires in the Central Coast Ranges. Photographs by the authors. CHAPARRAL AND WILDFIRES by Jon E. Keeley and Sterling C. Keeley Two aspects of the Mediterranean climate in Califor- nia play a role in promoting widespread wildfires in chaparral. One is summer drought, which produces a readily flammable fuel source. Another is winter and spring rain, which is coincident with mild temperatures, producing growing conditions that result in dense, con- tinuous vegetation capable of sustaining fires over large distances. Wildfire Frequency Chaparral fires occur on average every two or three decades on a given site, but there is some debate over whether this is an artifact of human interference. Scien- tists argue whether wildfires are more or less frequent today than in the past. Humans have two opposing roles in the present fire regime in California chaparral: start- ing and putting out fires. Despite extensive fire preven- tion campaigns, humans are responsible for igniting the vast majority of all wildfires, and often these fires occur under the worst weather conditions, such as the Santa Ana winds in Southern California. Only about five per- cent of fires are started by natural causes (lightning). On the other hand, some scientists argue that, in the absence of fire suppression, chaparral would burn at regular intervals anyway. Jason Greenlee and Jean Langenheim made a survey of the distribution of lightning-caused fires in conjunction with known pat- terns of fire in the Central Coast Ranges. They con- cluded that the "natural fire cycle" for the inland reaches of Santa Cruz County was up to one hundred years and was probably longer in the coastal and lower elevational areas. Such conclusions undoubtedly do not hold for all regions. Obviously, some sites may have burned more often while others may have been fire-free for extended periods of time. 18 Post-Fire Evolutionary Trends Wildfires are likely to have played a major role in the evolution of chaparral vegetation. Dominant shrub spe- cies exhibit adaptations that can be interpreted as evolu- tionary responses to fire. Shrub species in chaparral form a continuum of post-fire regeneration ranging from those dependent on seedling recruitment to sprout- ing species that rarely establish seedlings after fire. The majority of species of California lilac or buck- brush (Ceanothus) or manzanita (Arctostaphylos) are commonly referred to as obligate-seeding species since the plants are completely killed by fire. Reestablishment of these species is ensured by a large seed pool lying in the soil beneath the burned plants, which establish see- dlings in the first year after a fire. Interestingly, after this first year, seedling recruitment is almost nonexistent. Populations of these shrubs are generally all the same age, dating from the last fire. Sprouting species of Arctostaphylos and Ceanothus, as well as the nearly ubiquitous chamise (Adenostoma fasciculatum), are capable of regenerating their original canopy from buds housed in a swollen burl near the base of the plant. These burls are produced as a normal part of development, and tiny burls are generally evident on even the smallest of seedlings. All three genera have populations that are variable in burl formation: some seedlings have burls and others do not. As the shrubs grow, burls tend to enlarge and produce small buds capable of regenerating new stems. In the absence of fire these buds are thought to be suppressed by hormones produced by dominant stem shoots. When fire kills these shoots, buds are released from hormonal suppression and give rise to an entirely new shoot system. These species also regenerate after fire from seedlings that arise from previously dormant seeds stored in the soil. After a fire the proportion of resprouts versus seedlings is highly variable, and populations of chamise either vigorously resprout or there is abundant seedling establishment. Factors that play a role in deter- mining these differences include fire intensity as well as previous fire history. Shrubs such as toyon (Heteromeles arbutifolia), scrub oak (Quercus dumosa), chaparral cherry (Prunus ilicifo- lia), mountain mahogany (Cercocarpus betuloides), and redberry and coffeeberry (Rhamnus species) seldom establish seedlings after fire. In mature chaparral these shrubs produce substantial seed crops that are widely dispersed. The seeds, however, are short-lived and ger- minate readily with adequate moisture; thus, a dormant seed pool does not build up in the soil. This, coupled with the fact that these seeds are easily killed by intense heat, accounts for their failure to establish seedlings after fire. All of these species can readily regenerate after fire by virtue of the fact that they are vigorous re- sprouters. The temporary vegetation that develops immediately after a fire and disappears as the shrubs regenerate is dominated by a wide diversity of annual species, but includes short-lived perennial species as well. The spec- tacular wildflower displays commonly observed the first spring after a chaparral fire are renowned. John Thomas Howell once wrote: "Since only the kiss of the flame is needed to rouse dormant seeds from decades-long sleep, is it not strange that botanists do not turn arsonists on occasion that some floral phoenix might arise from the ashes?" Perennial herbs are conspicuous in the first spring after a fire, and their presence results from resprouting of bulbs or other buried parts. Included are all of the bulb-forming monocots such as species of Allium, Bloomeria, Brodiaea, Calochortus, and Chlorogalum, as well as dicots such as Paeonia californica and Marah macrocarpus. Seeds of these species do not require fire for germination, and their seedlings are generally uncommon in the first season after a fire. As the shrub canopy returns these species persist, but they produce depauperate growth in most years and due to low light levels they seldom flower under the canopy. The excep- tion to this are vines such as Marah macrocarpa or spe- cies of Cuscuta or Convolvulus (Calystegia), which are capable of reaching into the canopy and flowering. Other "temporary", not entirely herbaceous, peren- nial species are commonly referred to as suffrutescents (obscurely woody). When these species are present after a fire they arise from seed stored in the soil. In contrast to bulb-forming perennials, which flower vigorously in the first year after a fire, these suffrutescent species are often inconspicuous the first year. However, spectacu- lar floral displays often occur in subsequent years in spe- cies such as Eriophyllum confertiflorum, deerweed {Lotus scoparius, or broom-rose (Helianthemum scoparium.) Annuals make up the most diverse component of the chaparral flora. They are most abundant in disturbed areas and flower in the first spring after a fire. Some of these species, such as Phacelia species, Emmenanthe penduliflora, and Papaver californicum, have been referred to as "fire annuals" or "pyrophyte endemics" because they may dominate a site in the first year after a fire and then disappear until the next fire. These spe- cies have seeds that lie dormant in the soil until germi- nation is stimulated by fire. Although longevity of these seeds has not been well studied, circumstantial evidence suggests that they may be long-lived, perhaps one hun- dred years or more. Other native annuals are quite opportunistic in that they are most abundant on burned sites but persist within gaps in the chaparral canopy. Examples of these include species of Cryptantha, Plagiobothrys, Amsin- ckia, Camissonia and Lotus. Some of these have poly- morphic seed pools where a portion of the seeds ger- 19 minate readily in the absence of fire and others require fire stimulation for germination. Some native annuals, such as Cordylanthus filifolius or species of Clarkia, are typically most abundant in gaps in mature chaparral, and their seeds germinate readily without special treat- ment. Such species, as well as ones with polymorphic seed pools, increase in abundance in more open com- munities, arising from repeated disturbance or along xeric margins. One explanation of the the striking contrast between the depauperate herb growth under mature chaparral and the flush of herbs after a fire may be the suppres- sion of germination by a toxin leached from the overs- tory shrub foliage. While this theory of "allelopathy" has gained widespread notoriety and is often discussed in college textbooks, there is good reason to question its significance in chaparral. Field studies have shown that seedlings that do establish under the chaparral canopy are readily consumed by small animals. This predation pressure, coupled with the poor conditions of low light, limited water, and insufficient nutrients under the shrub canopy, has more likely resulted in evolutionary selec- tion for species of herbs with seeds that remain dormant until after fire. Fire-Stimulated Seed Germination Certain species of shrubs, herbs, and suffrutescents have seeds that require fire for germination. Although our information on the subject is far from complete, there are two well-documented mechanisms. Certain plants, such as Ceanothus species, broom-rose, and spe- cies of largely herbaceous genera such as Lotus or Lupi- nus, are stimulated by the intense heat of fire. These spe- cies are all characterized by seed coats with a well-developed cuticle that prevents uptake of water and consequently germination. Heat either melts or cracks this cuticle. Another mechanism studied in recent years is the chemial stimulation of germination by a compound produced by the charring of wood. This has been observed in species oiPhacelia and in Emmenanthe pen- duliflora, Eriophyllum confertiflorum, Silene multiner- via, and Papaver californicum. These species do not pro- duce seed coats with an impermeable cuticle and apparently are capable of taking up water, yet still do not germinate. Apparently the stimulatory chemical affects permeability, perhaps allowing greater oxygen uptake of some membrane under the seed coat. This is suggested by experiments that show that removing or puncturing the seed coat and inner membrane results in germination. The chemicals responsible for stimulating germination have not been identified, but some infor- mation is available. The compound is produced by the heating of wood, not necessarily that of a chaparral 20 shrub. The compound is destroyed if the charred wood is allowed to burn until ashed. It is a water-soluble com- pound that works in very small amounts. Preliminary studies suggest that this compound is a sugar, perhaps xylose or something similar, produced as a high- temperature degradation product of lignin or hemicel- lulose in the wood. In summary, many species of shrubs as well as herbs have seeds that require either intense heat from fire or a chemical produced by the heating of wood for germi- nation. Some species have a near-absolute requirement for this stimulus, whereas in others only a portion of the seed crop requires it. Most species are stimulated by either heat or charred wood; however, some exhibit a synergistic effect from the combination of both factors. Artificial Reseeding of Chaparral after Fire Agencies concerned with managing chaparral lands often seed recently burned sites with non-native herbs, Lolium perenne (ryegrass) in particular. "Type conver- sion" programs may seed in order to produce fuel loads sufficient for repeat burns in successive years, which will replace chaparral with grassland. More commonly, the justification for seeding is that species such as L. perenne are thought to establish a better plant cover and reduce soil erosion. There is evidence that this practice is having negative effects on the natural regeneration of chaparral. One of Dense herbaceous growth after a chaparral fire. the disastrous effects of this form of manipulation is that the ryegrass readily outcompetes native herbs. The negative effects of this are practical as well as aesthetic. Not only are wildflower displays greatly diminished on artificially seeded sites, but the soil-stored seed crops of herbs are diminished for the next fire. Under natural conditions the post-fire flora does a good job of revegetating the landscape after fire, and it costs noth- ing. Artificial seeding, however, has disturbed this system. Ryegrass replaces the native flora, but its seeds are short-lived and are not retained in the soil. Chaparral in the Absence of Fire It has been hypothesized that in the absence of fire chaparral would be replaced by other types of vegeta- tion. A number of studies of chaparral areas unburned for one hundred years or more have shown that over this time span chaparral is relatively stable and resistant to invasion. Old stands of chaparral are often described as "decadent," "senescent," "senile," or "trashy" —terms that lack clear definition and are based on little more than anecdotal observations. They derive from the fact that there is selective death of short-lived species in unburned chaparral as chaparral matures, there is a nat- ural thinning of shrub density, and dead stems accumu- late, giving the impression that the stands are unproduc- tive. Whether or not productivity (biomass) of chaparral decreases with age is unknown, although some studies are purported to have shown this. The truth is that chap- arral stands over one hundred years of age are often quite productive, and many species remain healthy and vigorous. Undoubtedly, as more information becomes available, we will find that these conclusions depend to a great extent on the dominant shrub species present in a given chaparral type. Recent work has shown that in older chaparral there is a continuous turnover of stems in resprouting species so that as stems die they are replaced by new sprouts form the basal burl. Sprouting thus plays a major role not only in recovering after a fire but also in the absence of fire. It is also clear from recent research that chap- arral species that resprout and do not establish seedlings after a fire actually require extended fire-free conditions for successful recruitment of new seedlings into the population. Chaparral under High Fire Frequency Regions where wildfires occur more than once a decade commonly have a highly degraded chaparral vegetation in which the shrubs are interspersed with non-native grasses and forbs. In general, obligate- seeding shrubs such as species of Ceanothus and Arc- tostaphylos are readily eliminated from chaparral if fires occur before sufficient seed crops have been stored in the soil—a period that may require fifteen to thirty years depending on the species and the site. Since sprouting shrubs always suffer some mortality during a fire, repeated fires at too close an interval can eventually eliminate these species also. Examples of this are read- ily seen around urban areas such as the Los Angeles Basin, where fires occur at unnaturally high frequencies. As a result of frequent burning by ranchers, extensive acreages of chaparral have been converted to grasslands throughout much of the Coast Ranges over the past two hundred years. Common Short-Lived Species on Recently Burned Chaparral Sites in Southern California SUFFRUTESCENTS Eriophyllum confertiflorum Compositae golden yarrow Helianthemum scoparium Cistaceae Lotus scoparius Leguminosae Penstemon spectabilis Scrophulariaceae Romneya spp. Papaveraceae Matilija poppy HERBACEOUS VINES Convolvulus spp. Convolvulaceae morning glory Cuscuta spp. Cuscutaceae dodder Lathyrus spp. Fabaceae pea Marah macrocarpus Cucurbitaceae wild cucumber PERENNIAL HERBS DICOTS Delphinium spp. Ranunculaceae larkspur Paeonia californica Paeoniaceae peony Sanicula spp. Apiaceae snakeroot Scrophularia californica Scrophulariaceae figwort Silene californica Caryophyllaceae Indian pink Solanum spp. Solanaceae nightshade MONOCOTS Allium spp. Amaryllidaceae onion Bloomeria crocea Amaryllidaceae golden stars Brodiaea spp. Amaryllidaceae brodiaea Calochortus spp. Liliaceae mariposa lily Ckloragalum spp. Liliaceae soap plant Elymus condensatus Poaceae rye Sisyrinchium bellum Iridaceae blue-eyed grass Zigadenus spp. Liliaceae star lily, death camas ANNUALS DICOTS Antirrhinum spp. Scrophulariaceae snapdragon Apiastrum angustifolium Apiaceae wild celery Cryptantha spp. Boraginaceae Camissonia spp. Onagraceae Chaenactis spp. Asteraceae Clarkia spp. Onagraceae Collinsia parryi Scrophulariaceae Chinese houses Cordylanthus fillifolius Scrophulariaceae bird's beak Emmenanthe penduliflora Hydrophyllaceae whispering bells Eucrypta chrysanthemifolia Hydrophyllaceae Gilia australis Polemoniaceae Gilia capitata Polemoniaceae Lotus salsuginosus Fabaceae trefoil Lupinus spp. Fabaceae lupin Malacothrix clevelandii Asteraceae Montia perfoliata Portulaceae miner's lettuce Papaver californicum Papaveraceae fire poppy Phacelia spp. Hydrophyllaceae Rafinesquia californica Asteraceae Salvia columbariae Lamiaceae chia Silene multinervia Caryophyllaceae Streptanthus spp. Brassicaceae MONOCOTS Festuca spp. Poaceae fescue 21 FLOWERS OF THE PHOENIX by Jean SmilingCoyote Top: California poppy (Eschscholzia californica); Bottom: Short- lobed phacelia (Phacelia brachyloba). According to the myth developed in classical Greece, the phoenix is a bird that periodically renews its life by dying and then arising from its own ashes. Like the phoenix, the chaparral plant community of California is rejuvenated by fire. On October 9, 1982, a wildfire in Dayton Canyon, a mountainous area west-northwest of Los Angeles, blackened 42,000 acres of grassland, southern oak woodland, chaparral, and coastal sage scrub. Like many other brush fires, this one was blown rapidly to the southwest by Santa Ana winds. These winds occur when a strong high-pressure system passes over the Great Basin of Nevada and Utah. Air flowing to the southwest "downhill" along the pressure gradient also flows down- hill physically, and in the process undergoes a rise in temperature and a fall in relative humidity. Santa Ana winds can reach hurricane velocity and cause much property damage as well as create the most hazardous fire conditions in Southern California. Their name comes from a mountain range in Orange County, to the southeast, over which they also flow. Though the Dayton Canyon fire was started by arson, records show that a fire passes through this area in the heart of the chaparral plant community of the Santa Monica Mountains about every ten years. The longer the interval between fires, the larger the area burned. There are two main factors involved in the vigorous growth of wildflowers following a fire in the chaparral. The first is the destruction of germination-inhibiting toxins that have been leached by rain into the soil from the tops of some of the shrubs, particularly chamise (Adenostoma fasciculatum). The second is the breaking of dormancy in seeds that may have lain in the soil for years, even decades. Freed from competition for light, water, and food, the herb layer exploded in the first season following the fire. These plants include annuals, biennials, and the herba- ceous above-ground parts of some perennials. The depth and composition of the ash, which vary with the severity of the fire and the origin of the plant material burned, can exercise a selective effect on the species dominating a given area. Many of the plants that were scarce or absent before a fire have some of the most beautiful and showy flowers in the chaparral, as shown in the accompanying photo- graphs taken among the Goat Buttes in spring 1983 fol- lowing the Dayton Canyon fire. Rainfall more than double the normal amount made this wildflower display one of the best ever. 22 Clockwise from top left: The burned and broken skeleton of the centuries- old Mendenhall oak stands in stark ¦ ¦i ¦ i .1 | ' ".. i ¦1 ,1 ¦ - I' ..... I i l I ¦. I B£u,t -*£'¦¦&&¦ '-:¦ '¦£¦ 23 :<:£& .i.- ;¦ . n4K* 5sHk ^^*£ The Inaja fire in Santa V,alvl hi November 1956. Photograph courtesy of the San Diego Historical Society Bishop collection. FIRE HISTORY IN SAN DIEGO COUNTY by Anthony T. Dunn San Diego County supports the largest acreage of chaparral of any county in California (nearly one mil- lion acres), representing over a dozen major chaparral associations. With its large ranges in altitude, precipi- tation, topography, and soils, the San Diego County chaparral and its fire history can in many ways be con- sidered representative of the Southern California chap- arral community in general. Because of the early desig- nation of national forest lands in San Diego County, the fire history of the county is better documented than in many other areas of the state, giving us a clearer picture of fire history trends, at least in this century. The chaparral community has been evolving in response to fire due to natural causes for millions of years. However, man's presence in California has signifi- cantly changed the patterns of fire. From the time of the earliest Indians to the present day, human use of fire, whether deliberately or accidentally, has had a distinct 24 and lasting effect on the vegetation of the state. Not only this, but our use and suppression of fire has altered the fire regime of the chaparral community. By changing the location, number, and timing of fires, we have created a completely new fire scenario. By building roads, fuel breaks, and fire-fighting organizations, we have changed the way in which fire responds to terrain, vegetation, and weather. And by building homes in the chaparral, we have changed the way in which we react to fire. Natural Fire Regime Though spontaneous combustion may have occurred occasionally, lightning was and is by far the greatest source of natural ignitions in Southern California. Lightning fires are common in Southern California and northern Baja California, since this area often experiences summer thunderstorms. These storms occur when unstable tropical moisture moves north from the Gulf of Mexico or the eastern Pacific. Rainfall is highly variable and usually comes in cloudbursts that dry up quickly. In San Diego County there are an average of about thirty lightning-caused fires a year. However, today these fires account for only five percent of the total number of fires in the county. Many of these lightning-caused fires occur in the pine belt or the desert slope of the mountains. Natural fires in the chaparral in pre-human times are thought to have been either very small or very large. Fires either failed to spread because fuel loading, fuel moisture, or weather conditions at the fire source were insufficient to carry a flame, or the fires spread unchecked until fuel, topographical, and weather con- ditions put them out. These fires might have burned for weeks, flaring up periodically when conditions became extreme, and might have covered hundreds of thousands of acres. There were no roads, settlements, or fire- fighters to check their advance. However, large fires during this period were also rare, occurring only when a combination of fire source, high-standing biomass (above-ground vegetation), a high percentage of fine dead fuels, and critical weather conditions occurred together. Patterns of Small Fires Though there are on average thirty lightning fires in the county per year, over ninety-five percent of these burn less than one-quarter of an acre (Keeley, 1982). This can be attributed partly to fire suppression, but the fact remains that most lightning fires occur under moderate weather conditions and may be extinguished by rainfall or wet vegetation before they can spread. Only a small percentage of lightning fires attain any great size, and none has exceeded 7,000 acres in San Diego County since 1910. Fuels are all-important to the occurrence of large fires, when fuel moistures are very high in living chap- arral, fires may be retarded or extinguished. Most chap- arral types will not easily burn until there is a continu- ous shrub canopy and a high proportion of dead fuel. Mixed chaparral stands generally attain high levels of fuel-loading and continuity between thirty-five and fifty years of age, making them capable of sustaining fire over varying weather and topographical conditions. This contrasts with the grassland and coastal sage com- munities, which contain high levels of dead fuels every summer. In San Diego County, the three worst histori- cal fire years occurred when greater than ninety-three percent of the vegetation in the county was over ten years old. Although warm, dry summer and fall weather in Southern California is often conducive to their occur- rence, large fires do not occur every year. In many years, even old stands of brush may not burn. Though not a hard and fast rule, large fires in mature chaparral often occur in drought years immediately following an extended wet period. Under favorable conditions, chap- arral plants show extensive growth, but may not be able to support this new biomass when drought occurs. Much of the new vegetation then dies back, sharply increasing the level of tinder-dry, dead fuels in the stand. Using tree-ring growth indices compiled by Schulman Strong winds are generated by the November 1956 Inaja fire in Santa Ysabel. Photograph courtesy of the San Diego Historical Society Bishop Collection. 25 (1947), it was determined that these circumstances occur in Southern California about every thirty-five to fifty years. The multitude of fires seen by Cabrillo in 1542 corresponds with one of the most severe post-fluvial droughts on Schulman's record. Severe fire years in 1928 and 1970 also followed this pattern. The overall picture that emerges of the pre-human chaparral environment is one of rare, periodic, and immense wildfires, with a return interval of thirty-five to fifty years. Episodic large fires burned off large acre- ages that then resisted reburning until the fuel levels reached a point where they could again support a con- flagration. For an example taken from modern times, the 118,000-acre Wheeler fire in Ventura County last year reburned much of the area last consumed in the 220,000-acre Matilija fire of 1932. This had the effect of creating large areas of even-aged brush, unlike the mosaic of fuel ages that we see today surrounding most urban areas. Indians and Settlers The debate over the extent and impact of aboriginal burning has been a long one, and there is still little agree- ment as to the degree to which the Indians partook in burning. Some tribes are known to have used fire fre- quently to improve seed crops such as chia and grazing for game animals and to clear brush to facilitate hunt- ing. For other tribes there is little or no information. In San Diego County, most data indicates that the Indians (Kumeyaay, Juaneno, Cupeno, and Cahuilla) primarily burned grassland areas, both for improved seed crops and to improve the quality of grasses used to make baskets. Though there are vague reports of when the Indians burned, it is generally agreed that most of their burning was done during the late summer and fall (Lewis, 1973). Whether they waited for or avoided crit- ical fire weather periods is not known. Though it is certain that the Indians had some impact on the fire regime of the chaparral, one can only guess the extent. Indian populations were small and limited to areas with water and food. Persistent burning in cer- tain areas undoubtedly altered vegetation patterns, but these patterns varied as population and land use changed over time. If the burning was limited primar- ily to grassland areas, the heat generated probably was not enough to carry the fire into the brush except under extreme conditions. The Indians, living mostly near their main food source, oaks, had little reason to ven- ture into the vast acreages of gameless and waterless chaparral. These areas probably burned only during periodic large fires. The establishment of the Spanish missions and ran- chos in California introduced great herds of cattle and sheep to the landscape, which ravaged the native vege- tation. Along with the livestock came the aggressively invasive annual Mediterranean grasses such as bromes (Bromus spp.), wild barleys (Hordeum spp.), and wild oats (Avena spp.). Unlike the native perennial grasses, which stay green in the summer, annual grasses grow vigorously in spring only to turn tinder-dry by June. By the beginning of the American period, around 1850, many of the native grasslands had been taken over by highly flammable annual species, which probably burned frequently and had disastrous effects on regener- ating chaparral. With the coming of the American settlers, stockmen, and gold-hungry miners, settlements spread throughout the mountains and canyons in areas where the Indians had rarely settled. During the gold rush in San Diego County, mountain towns sprang up almost overnight. The new influx of people raised the number of poten- tial ignitions beyond anything previously experienced. The miners, many from the moist East Coast, were often extremely careless with fire. Worse, though, were the stockmen, who burned off forests and grasslands both to improve the grass for the next season and to prevent anyone else from using their range. Stockmen in the late nineteenth century were responsible for thousands of destructive fires. The Modern Era By the 1880s the growth of population in Southern California made clear the need to protect surrounding mountain watersheds as a source of water. The U.S. government began, in the 1890s, to establish some of the nation's first "forest reserves" in Southern California, and in 1910 the U.S. Forest Service began the first organized fire-suppression efforts in the county, fol- lowed by those of the California Division of Forestry (now the California Department of Forestry) in 1924. The twentieth century has seen a population explo- sion in Southern California, especially since the end of World War II. This growth, particularly at the ever- expanding suburb-chaparral interface, has increased the potential of fire to a near-saturation level of ignitions. Even the improvements in fire-fighting techniques and equipment have not been able to keep up with the num- ber of fires. In some places fires are virtually guaranteed to occur whenever fuel and weather conditions make them possible — a situation very unlike pre-human times when weather and fuel conditions may have reached critical levels many times without ignitions. Fire-suppression policies and techniques have created a situation where most fires under moderate weather and fuel conditions are suppressed when relatively small. Only fires occurring under the most severe con- ditions reach the size of pre-historic fires. These modern large fires usually occur under weather conditions that 26 generate few, if any, fires from natural causes. In the two-week period beginning on September 25, 1970, during a severe Santa Ana wind, 773 fires started in Cal- ifornia, none of which was natural in origin. Though the average size of fires today is much smaller than in pre- human times, there are also twenty times as many fires. Fire suppression and anti-fire propaganda have had little effect on the number of ignitions. San Diego County alone experiences 500 to 1,000 wildfires a year, and in some areas the fire frequency has doubled or tripled since 1900. The timing of large fires since the arrival of Euro- peans has also changed to a considerable degree. As stated above, most natural lightning fires occurred in summer. Fires driven by Santa Ana winds were undoubtedly rare, though there have been documented cases of fires smouldering for weeks or months in logs and trees only to break out when burning conditions became extreme. Today, wildfires occur in every month of the year, with September by far the most severe. Com- bining the heat and dryness of summer with the poten- tial for Santa Ana wind conditions, over forty percent of the acreage burned in the county since 1910 has been consumed in this single month. October, November, and December experience many more occurrences of Santa Ana winds than September, though usually under less severe weather conditions, often after rain-bearing storm fronts have passed through. Unlike pre-human times, when the vast majority of acreage was burned between July and early September, two-thirds of the acreage burned in this century has been consumed between September and the end of November. Can Man and Chaparral Co-Exist? Even today, the fire ecology of the chaparral con- tinues to change. The more often a stand of vegetation burns, the more light, flammable fuels tend to replace the heavier chaparral fuels. This in turn perpetuates a higher fire frequency. As species diversity declines and soil erosion increases, plant communities become less able to resist degradation and potential desertification. As the population of Southern California continues to grow, larger and larger areas will see a saturation of igni- tion sources, though many remote areas may maintain a semi-natural fire regime. In San Diego County, for example, fire history modeling indicates that there has been a natural build-up of old fuels in the remote north- east and southeast parts of the county that will almost certainly result in a series of large fires by the end of the decade. There is little reason to hope that large wildfires will ever be stopped in the chaparral of California, nor should there be. Wildfires are as natural a part of the California landscape as chamise and manzanita. The Dropping a fire-retardant slun> lioiu a C 130 air tanker. Photograph by Doug Allen, courtesy of the California Department of Forestry. problem we face today is striking a balance between too much fire and not enough. Finding a way for man, fire, and chaparral to co-exist will undoubtedly occupy the efforts of land managers and conservationists for many years to come. References Dodge, J. Marvin. 1975. Vegetational changes associated with land use and fire history in San Diego County. Unpub- lished doctoral dissertation, University of California, Riverside. Keeley, Jon. 1982. "Distribution of lightning-and man-caused wildfires in California," in E.C. Conrad and W. Oechel, Dynamics and management of Mediterranean-type ecosystems. PSW Forest and Range Experiment Sta- tion. PSW-58. Lewis, Henry T. 1973. Patterns of Indian burning in Califor- nia: ecology and ethnohistory. Ballena Press. Minnich, Richard A. 1983. "Fire mosaics in Southern Califor- nia and northern Baja California," in Science, 219:1287-1294. Schulman, Edmund. 1947. Tree-ring hydrology in Southern California. University of Arizona Bulletin. Laboratory of Tree-Ring Research. Bulletin No. 4. 27 FIRE AND CHAPARRAL MANAGEMENT AT THE CHAPARRAL/URBAN INTERFACE by Philip J. Riggan, Scott Franklin, and James A. Brass The historic Bel Air fire of 1961 was not unusually large or fast-moving, nor was it a disaster for the native chaparral ecosystem. Yet it was disastrous for residents of the area, a consequence of unrestricted urban development in the chaparral of Southern California. Its costs included human suffering and financial loss from the destruction of 484 of 2,300 homes. Since that time fire-fighting techniques have improved and ordinances have been enacted to increase clearance around structures and to encourage the use of non-flammable roofing materials. Yet within the origi- nal fire perimeter there are now 3,500 structures of aver- age value greater than $1.3 million, and the chaparral has flourished to the point where it can spread a destruc- tive fire once more. Another disaster is in the making. Chaparral is adapted to recurrent fire, and burning, in fact, is the only way to reduce heavy fuels without altering the community composition. Yet urban areas continue to expand into the chaparral and become more finely subdivided and vulnerable to fire. Moreover, the remaining chaparral is an aesthetic and biological resource for wildlife. Is there not a way to break the pat- tern of fires so destructive to humans without forever altering the remaining ecosystem? We believe that prescribed burning, together with other hazard- reduction measures, will ameliorate the problem. In Southern California the wildland/urban interface problem is most critical in the Santa Monica Mountains where Santa Ana winds, following a natural corridor out of Newhall Pass, can push a fire across the moun- tains to the coast within a few hours. All too often, homes have been built both along ridgelines and in adja- cent canyons with steep intervening hillsides. Poor vege- tation clearance, flammable roofs, and restricted access place many structures at serious risk. During the Bel Air fire over one-half of the houses with wood roofs and less than ten feet of brush clearance were destroyed; less than one percent with approved fire-resistant roofs and clear- ance of one hundred feet were lost. There are islands of chaparral isolated by develop- ment that cannot be readily managed and will contrib- ute to destructive fires in the size range of five to fifty acres. But expanses of chaparral ranging from a few hundred to thousands of acres have the potential for producing conflagrations that can spread into urban neighborhoods. Beverly Hills, Bel Air, Brentwood, and Pacific Palisades continue to be imperiled by the spread of major wildfires in the Santa Monica Mountains. Some adjacent canyons are covered by chaparral with no historical records of fire and major build-ups of fuel that could generate disastrous fires. Although much can be done to improve the fire safety of structures, to do so without reducing other risks is to accept that large fires will continue unabated. Actions can be taken to significantly reduce their threat. Over the past decade the application of prescribed fire has matured in the national forests and on lands under state responsibility in California. We feel that, despite the inherent risks, the time has come to apply managed fires to critical lands at the wildland/urban interface. The value of prescribed burning is that frequent fires maintain chaparral with a relatively low biomass and a small proportion of dead wood. Young chaparral, espe- cially ceanothus, is often incapable of spreading fire under moderate weather or high live-fuel moisture. With high winds and low humidity, young stands burn with reduced flame lengths and tend not to "spot," that is, spread by air transport of glowing fire brands. Lateral spread of large fires and their resistance to control are reduced, and soil heating damage and subsequent post- fire flooding and debris production should be lessened. Wildfires will not be eliminated by prescribed burning, but the impact of large fires should be drastically reduced if young chaparral is maintained in a shifting mosaic of age classes. Not all land need be treated as long as significant portions, and especially key terrain or fire corridors, are managed. Altering wildfire regimes by age-class management, which is designed to maintain the native vegetation, is ecologically more sound than any widespread replace- ment by grasses or other low-biomass plantings. Such vegetation-type conversions frequently fail and reduce an otherwise complex ecosystem to fields of black mus- tard or buckwheat. The Stone Canyon research and development project was organized to avert a replay of the 1961 Bel Air fire while preserving scenic quality, wildlife habitat, slope stability, and water quality. Prescribed fire is being introduced to the canyon as the primary method of fuel reduction. Participating in this interagency effort are the County of Los Angeles Fire Department, the City of Los Angeles Fire Department and Department of Water and Power, and the USDA Forest Service Pacific South- west Forest and Range Experiment Station. A series of 28 meetings with local homeowners have involved the public in planning and generated strong local support. The 600-acre Stone Canyon, in the city of Los Angeles, is the site of major storage reservoirs operated by the Department of Water and Power. It is bounded by Mulholland Drive and Sherman Oaks on the north and the community of Bel Air on the south. Homes line the perimeter, overlooking the canyon on the west and northeast. The proximity of structures demands extraor- dinary measures for fire containment and detailed knowledge of the vegetation and fuels so prescriptions can be tailored to specific sites. Research was initiated to map vegetation, monitor fuel treatments, and predict long-range ecological effects of management. The native vegetation at Stone Canyon forms an eco- tone between coastal chaparral, dominated by Ceanothus spinosus, C. megacarpus, Rhuslaurina, and Heteromeles arbutifolia, and coastal sage scrub with Artemisia californica, Eriogonum fasciculatum, and Saliva mellifera. Small stands of Quercus agrifolia and Juglans californica occupy drainages and some north- erly aspects. Minor changes in aspect are mirrored by major changes in the species present. Such diversity dictates site-specific prescriptions to assure regeneration and can aid in containing prescribed fires. Because of its com- pact structure and high proportion of fine stems, coastal sage scrub will more readily burn than chaparral when weather is mild and live-fuel moisture is high. Commu- nities where ceanothus predominates can aid in contain- ing a prescribed fire spreading in the sage scrub. As live- fuel moisture declines in the summer the ceanothus can then be treated. Ceanothus spinosus should resprout reliably after burning or cutting. Ceanothus megacarpus may suffer poor regeneration if soils are moist during burning but otherwise should establish from prolific seedlings. The overstory trees of oak and walnut are a special resource that should be protected from fire. However, their understory can be burned during cool weather to elim- inate accumulated ground fuels and produce a shaded fuel break. Aerial photographs have been used to classify vege- tation and site plots used to estimate such parameters as leaf area, total biomass, and dead material of the pri- mary communities. This study is unusual in the level of detail being used to assess whether a full management program will significantly alter vegetation and its dis- tribution in the chaparral community. Stone Canyon has been divided into eight primary management zones as determined by small watershed boundaries, existing fuel breaks, and similar difficulty of treatment. Under the management plan, prescribed fire will be applied in stages extending over three to five years beginning in 1986. Carrying the treatments over time will allow us to detect and check the development ^Vftp. ¦ »-£¦ * ¦«-_¦"*¦ ..*!* $¦-¦ ¦si*:,* .. - :-.V* '¦* '' %* ¦-. £r:" J**>V *!&>.< The greatest flame lengths during the June 30, 1986 prescribed fire in upper Stone Canyon were produced in felled chaparral and adjacent Ceanothus. of problems in application or plant community recovery. The first treatment widened to 300 feet the existing hundred-foot clearance around structures by hand- clearing and burning of piled brush, although large individual shrubs, especially ceanothus and toyon, have been pruned to tree form where possible. The greatest management concern here is to avoid establishment of woody subshrubs such as buckwheat or black sage, which can result when the cover of mature chaparral is permanently reduced. These can accumulate a large mass of finely divided, small-diameter stems and dead wood and can propagate fire with even moderate weather and fuel moistures. Shrubs that resprout within this zone will be undisturbed. Prescribed fire was applied in two stages to the upper small watersheds of Stone Canyon during late spring and early summer 1986. In the first stage, piled brush was burned during the early morning under low clouds and fog. High humidity and low air temperature were necessary to control spotting from the dead fuel. Fifteen engine companies from the city and ten fire-fighting crews from the county fire department were deployed to assure protection of structures and contain the fire. Some regeneration problems can develop from this work if seed is destroyed by prolonged soil heating beneath piled brush or if the scarification requirement for seed germination is not met where no fire is applied. Areas of Ceanothus spinosus were also felled in place and burned. Although this species sprouts vigorously, there could be some mortality if the shrub sprouts during the interval between cutting and burning. 29 In the second stage, twenty-six acres of crushed broadleaved chaparral and standing coastal sage and south-slope chaparral were burned on June 30. An addi- tional fifty-two acres of south-facing chaparral were burned July 1. During burning the humidity averaged thirty-five percent, air temperature was 30° C, and wind speed was eight to twelve km/hr from the south to southeast. Most of the chaparral and sage scrub burned was ignited from a low-flying helicopter by drip torch or helitorch. Beginning at the downwind fireline, succes- sive passes ignited narrow strips of vegetation. Despite several attempts, the ceanothus could not be directly ignited. Large patches of coastal sage did support com- bustion with three- to six-meter flame lengths, spread- ing fire into some upslope stands of Ceanothus megacarpus and chamise. Chamise chaparral on southerly aspects burned readily the second day. Future treatments may include understory burning in small oak woodlands and hand felling or mechanical crushing on moderate slopes of ceanothus or Quercus dumosa prior to burning to increase the dead fuel load- ing and allow fire to spread during more moderate weather. Late spring treatments will be used to avoid loss of ceanothus and coastal sage communities that must reproduce from seed. Firing will be avoided on steep, erosive, south-facing slopes. The threat of catastrophic wildfire is a pervasive prob- lem faced by the citizens of Los Angeles where urban development meets wildland chaparral. We see great promise in the Stone Canyon project for addressing this threat and building the public confidence and inter- agency cooperation necessary to manage chaparral lands at the sensitive wildland/urban interface. Reference Howard, R.A., D.W. North, F.L. Offensend, and C.N. Smart. 1973. "Decision analysis of fire protection strategy for the Santa Monica Mountains: an initial assessment". Menlo Park, California, Stanford Research Institute. The diversity of vegetation within Stone Canyon and environs is shown in this computer generated classification of spectral data from a 12-channel thematic mapper simulator mounted aboard a high altitude aircraft. Six primary classes are shown in these two images: at the left are associations of Quercus agrifolia-Juglans californica (white), Adenostoma fasciculatum-Rhus laurina (gray) on south-facing slopes, and mixed chaparral on east-facing aspects (black); at the right are coastal sage scrub (white), north-facing associations dominated by Ceanothus spinosus and Heteromeles arbutifolia (gray), and east-facing stands of C. spinosus and R. laurina (black). «,«* 4S&a -"5&i}^i '' * ft ** • -%^, • m?*x? te€*r ^"b^ >*t* %£**' ^^^¦k. ¦ *--i.-?;¦.-»-•'¦¦ , ¦» ¦*¦-¦* T' j.*.*'.--, v.',*."' -s--^j^as*?*; j_ 4).. Pinnacles National Monument. Photograph by Richard Frear courtesy of the National Park Service. PLANT SUCCESSION ON PRESCRIBED BURN SITES AT PINNACLES NATIONAL MONUMENT by Melanie Florence The effect of prescribed winter fires on native vege- tation in chaparral plant communities is currently a major subject of debate. Many ecologists believe that burning during the cool season, the season in which prescribed burning is often performed, could be detrimental to the seed bank of fire followers. Seeds are exposed to heat when the ground and surrounding air are moist. Also, the fire may not be hot enough to ger- minate the seeds of certain non-sprouting shrubs. Chaparral species have long existed under a regime of natural (lightning-caused) fire occurring during the hot, dry summer months. As a result, chaparral vegetation has come to be dependent on periodic fire to rejuvenate itself. An interval of thirty to sixty years appears gener- ally to be most favorable for the maintenance of most types of chaparral. Because of wildfire suppression during the twentieth century, the natural fire cycle has been interrupted in many chaparral areas. Large acreages of chaparral now exist with a continuous cover of decadent brush contain- ing large amounts of dead material. A wildfire occur- ring in one of these areas could burn with high intensity 31 over thousands of acres, causing severe environmental damage and site degradation. The use of prescribed burning has increased as a means of breaking up con- tinuous brushfields and reducing unnaturally high accumulations of fuel to improve wildlife habitat and range lands. The response of herbaceous species after cool-season fire was studied at Pinnacles National Monument in the northern Southern California Coast Range in Monterey and San Benito counties. Three chamise {Adenostoma fasciculatum) chaparral south-facing sites were burned in 1981 during February, April, and June. These sites were studied for two consecutive spring seasons to com- pare species composition and successional trends with documented wildfire studies. Also, data obtained from a nearby July 1978 wildfire site adjacent to the monu- ment on Bureau of Land Management land were com- pared with the prescribed burn site data. Typical Chaparral Succession Chaparral succession after a warm-season wildfire follows an established progression. During the first few post-fire years, native annual and perennial specialized fire-follower plants are abundant on the burn site. These species have refractory seeds, meaning seeds that need scarification in the form of heat or charate (chemicals released by fire-charred shrubs) to germinate, so are found only on burn sites in the early post-fire years. These seeds germinate after fire from long-lived seeds present in the soil and deposited before the occurrence of fire. Other specialized fire-follower species have root burls, lignotubers, or underground stems that sprout after fire destroys the apical parts of the plant. Exam- ples of specialized fire-follower species in the Pinnacles area include: snapdragon {Antirrhinum kelloggii), buck brush (Ceanothus cuneatus), golden ear-drops Dicentra chrysantha), whispering bells {Emmenanthe pen- duliflora), Eucrypta chrysanthemifolia, deerweed {Lotus scoparius), evening primrose {Oenothera micranthd), Rafinesquia californica, and Thelypodium lasiophyllum. Generalized fire followers are also found on burn sites during the early post-fire years. These species also grow in disturbed areas and on openings in mature chapar- ral, so they are not restricted solely to early post-fire-year burn sites. They are often non-native weedy species with non-refractory seeds. Generalized species have broad ecological tolerances that allow for extended survival under changing conditions. The presence and abun- dance of the annual species are related to the amount and distribution of rainfall in a growing season. Gener- alized fire-follower species in the Pinnacles area include: wild celery {Apiastrum angustifolium), foxtail chess {Bromus rubens), Cryptantha muricata, yerba santa {Eri- odictyon tomentosum), filaree {Erodium cicutarium), foxtail fescue (Festuca megalura), bird's foot trefoils {Lotus humistratus, L. strigosus, L. subpinnatus), chia {Salvia columbariae), and pygmy-weed {Tillaea erectd). In the first year following a fire, a burn site is typically occupied predominantly by fire-following forbs (herba- ceous dicots), and grasses are less important. Special- ized fire-following forbs decrease in abundance with succeeding years because of an absence of fire as a dormancy-breaking influence and/or the inability of these species to compete with grasses and generalized Typical prescribed burn sites at Pinnacles National Monument. Close-up of a burn site in the foreground and patches of burned areas on the hills. Photograph by Brian Mathos. fire followers. Fire-following shrubs and subshrubs gradually become larger, eventually crowding and shad- ing out the herbaceous plants. Subshrubs such as deer- weed and black sage (Salvia mellifera) reach maximum development the third or fourth year after a fire. Dorm- ant shrubs such as chamise and buck brush increase in cover percentage in succeeding years, while generalized annuals and subshrubs are restricted to smaller and smaller openings. After ten years or so, a dense shrub cover with little understory has again developed. Dense growth of the shrubs (many with flammable compounds in their foliage), accumulation of fuels, and summer drought eventually result in another fire. Succession on Study Sites The vegetation found on the wildfire study sites and two of the prescribed burn study sites (the spring burn sites) closely approximate the herbaceous plant succes- sional trends described above. Dense chaparral and hot, dry weather resulted in a high-intensity burn on the wildfire site. The spring burns both had weather, fuel conditions, and fire behavior resulting in moderate- intensity burns. However, the winter burn had condi- tions resulting in a low-intensity burn. The wildfire and spring burns were hot enough to heat-stimulate the seeds of specialized fire followers and to form charate. The fires killed most non-refractory grass seeds and some generalized forbs on the low-intensity burn site. Grass cover was high in the first year following the fire, and generalized forbs were more abundant. Species diversity was higher on the moderate-intensity burn sites, and these sites were floristically more similar to each other than to the low-intensity burn site. Of all factors considered in the study (soil types, topographical variations, fire intensity, weather after fire), it appears that fire intensity has the strongest effect on herbaceous species diversity and dominance. The high-intensity wildfire resulted in fewer total species, but those found were primarily forbs, and typically fire- following species. Most heat-sensitive seeds apparently were killed by the fire. Moderate-intensity spring burn sites were dominated by fire followers but also contained other species normally found in annual grassland com- munities or on open rocky sites that apparently survived the fire in cooler pockets. The low-intensity winter burn site was co-dominated by an annual grass and a gener- alized fire-following forb. Species of annual grassland and of specialized fire followers both grew after the low- intensity fire. The temperature apparently was not hot enough to kill most heat-sensitive seeds but was hot enough in spots to form charate and to heat-stimulate the seeds of some specialized fire-following species. Annual grasses constituted a larger proportion of the community than is normally found after a wildfire. Because of the high grass cover during the first year after the fire, the low-intensity burn site was dominated by grasses the second post-fire year. All other study sites had the expected, but much smaller, increase in grass cover the second post-fire year. Increased competition from annual grasses may reduce the dominance and eventually the occurrence of specialized fire followers if low-intensity fires occur frequently or over large areas. Other studies need to be done to see if these results can be duplicated throughout California chaparral. If cool-season prescribed burns are of moderate or high intensity, they might not be as detrimental to native spe- cies as many ecologists fear. References Biswell, H.H. 1979. Chaparral ecology short course. Univ. Ext., Univ. Calif., Davis. Hutchison, S.M. 1975. Herbaceous secondary succession in San Diego County chaparral. M.S. thesis, San Diego State Univ., Calif. 99 pp. Keeley, S.C. and J.E. Keeley. 1981. "The role of allelopathy, heat, and charred wood in the germination of chapar- ral herbs." In Proceedings of the symposium on dynamics and management of Mediterranean-type ecosystems. U.S.D.A. For. Serv., Gen. Tech. Report PSW-58, Berkeley, CA, pp. 128-34. Keeley, S.C, J.E. Keeley, S.M. Hutchison, and A.W. Johnson. 1981. "Post-fire succession of the herbaceous flora in Southern California chaparral." Ecol. 62:1608-19. Menke, J.W. 1980. Dept. of Agron. and Range Sci., Univ. Calif., Davis. Personal communication. Sweeney, J.R. 1956. "Response of vegetation to fire: a study of the herbaceous vegetation following chaparral fires." Univ. Calif. Publ. Bot. 28:143-250. 33 GROWING NATIVES: MORE FROM THE CHAPARRAL by Nevin Smith Genus: Cercis Family: Leguminoseae, subfamily, Caesalpinioideae Genus: Ribes Family: Grossulariaceae In the last installment of this column we examined the snowdrop bush (Styrax officinalis), one of the shrubby treasures of the the chaparral. There are, of course, many more. This time I will describe two more personal favorites, both widely distributed in our drier hills. Both are often found in slight draws, on the upper banks and benches of streams, and on open flats, fully exposed but perhaps retaining a little extra moisture underground through the season. Western redbud {Cercis occiden- talis), should be familiar to anyone who has travelled the back country in spring, for it frequently dots whole slopes with great puffs of pink to rose-purple. Chapar- ral currant (Ribes malvaceum), is more sparingly dis- tributed and often produces its lovely showers of rose to white blossoms in mid- to late winter. Cercis occidentalis is a variable species, sometimes relatively consistent in its more obvious features within populations, but often differing widely among popula- tions. In portions of Lake County, for example, are found stands of distinctly tree-like plants, with arching canopies ten to fifteen feet high or more, reminiscent of C. canadensis, an eastern species; nearby are popula- tions of considerably shorter, many-trunked shrubs. All are easily identified by smooth-barked, zig-zag stems, which present a beautiful tracery in winter when the plants are leafless. The younger stems are often heav- ily tinged with purple. The round to kidney-shaped leaves are attractive throughout the growing season and spectacular when they first emerge, polished and bronze-tinted, in spring. When fully expanded, they generally measure one and one-half to three inches across and are dark green to blue-green above and paler beneath. Their usual bright yellow fall color can vary to orange or even red. The flowers alone are ample reason to treasure the plant: appearing in early to mid- spring, they are vaguely pea-like in form, individually under one-half inch long but presented in small clusters all along the bare stems and painted glowing shades of rose-purple to silvery pink. Friends have described at least two populations in Southern California with uni- formly white flowers. Clusters of drooping, flattened seed pods expand to two to four inches long and take on purple to mahogany hues by late summer. They are held through much of the winter and are oddly decora- tive against the bare stems. Such variable ornamental features make clonal selec- tion worthwhile. Rancho Santa Ana Botanic Garden has introduced a selection called 'Claremont', described as "exceptionally heavy flowering and with fine deep color," and an equally beautiful white-flowered clone, designated so far only as the form alba. Unfortunately, neither is widely available in the trade. I am propagating a shrubby clone with dark rose-purple flowers from Lake County. Perhaps these will find broader circulation. In Ribes malvaceum we find more subtle variations. This is a shrub of medium size—I have seen a few around eight feet tall in the wild, but most are four to six feet. Closely branched in full exposure, it grows more sparse and spindly when shaded by taller shrubs and trees. The branches are nearly always held erect. Both stems and leaves of the new growth are densely covered with sticky hairs that lighten their apparent color and give them a strong, pleasantly resinous fragrance reminiscent of favorite haunts in the chaparral. The leaves are one to three inches across, broadly lobed and heavily textured. In the typical form they are light green above and considerably paler beneath; the variety viridifolium found in Southern California has green undersides, but other distinctions would interest only a botanist. This species is basically fall- or winter- deciduous, but I have seen individuals that have already begun their new growth by the time the old leaves fall. Fall color is not normally one of the stunning features of this plant. However, in mid- to late winter, seemingly oblivious to rain and cold, it erupts in a striking display of small rose to white blossoms, held in dense, droop- ing clusters and opening over a period of several weeks. Given enough pollinators (this depends mostly on the weather), strings of dark purple berries will later develop. These vary in flavor from sweet and spicy to insipid, though the birds enjoy them in any case. Again, clonal selections, primarily for compact habit and flower color, seem warranted. 'Wunderlich', a heav- ily blooming selection with bright pink flowers, is at least somewhat available commercially, and others may be on the market soon. Culture and Propagation Both western redbud and chaparral currant fall in the "cast iron" cultural category. Both thrive in a variety of exposures, though more than light shading will signifi- 34 Cercis occidentalis. Drawings by Angel Guerzon. cantly reduce flower production. Both tolerate many soils. Watering regimes may vary from that accorded "normal" garden shrubs to nothing beyond normal rain- fall, except in our hottest and driest climates, once the plants are established. Both are at home in searing heat, and should, if taken from northern populations, toler- ate occasional winter lows of 10° F. or less. One climatic limitation should be noted: western redbud grows well but tends to bloom poorly along our milder sections of coast, apparently because of insufficient winter cold for proper bud formation. Landscape use will be governed to some extent by cul- ture in both cases. Given average garden watering and fertilizing and occasional pruning of basal sprouts, western redbud makes an attractive small tree for the front yard; planted in rows along property lines and left shrubby, it can form tall, informal screens. Under the same conditions chaparral currant should form a broad thicket unless thinned and pruned for a more definite, open structure; it could be lined out and sheared as a hedge, though the rough-textured foliage lacks the refinement normally associated with this use. With min- imal watering and feeding, even the redbud is an easily controlled shrub (or miniature tree with proper prun- ing), and both plants may be subjected to the uses described above on a smaller scale. Where space per- mits, I would use them as they appear in nature —in irregular, open drifts over banks, hillsides, and open fields. Given their large, vigorous root systems, it seems dubious that either would be appropriate as a container subject (though I have kept a pet plant of the redbud this way, terribly rootbound but thriving, for several years). For the gardener desiring quantities of either species, there is happily no particular obstacle to their propaga- tion. Like many legumes, western redbud has hard, dense seed coats that imbibe water poorly until softened or abraded; a simple, reliable method for doing this with large numbers of seeds is to drop them into a cup of nearly boiling water and allow them to sit and cool over- night or even several days. Refrigerating them for a couple of months or planting outside in fall, to sit through winter, will assist in germination. The seedlings should be transplanted to separate pots or the ground when quite young to avoid breakage of the vigorous tap roots. Successful seeding of chaparral currant should involve no more than separating the seeds from the berry pulp and planting them before they dry and shrivel; again, a natural or artificial winter may aid germination. Where clonal propagation is desired, chaparral cur- rent is clearly the easier plant to handle. Cuttings may be made, using only mild rooting hormones if any, at almost any time of year, though leafy cuttings must be misted or otherwise protected from dehydration. Young, active shoots of the redbud, which I have found most successful as cuttings, are decidedly more delicate, and misting seems almost mandatory. Grafting is frequently employed with other Cercis species, and should be suc- cessful if one has the patience and knowledge of this technique. [See Growing Natives, Fremontia, July and October, 1984, for further details on propagation.] Ribes malvaceum. 35 NOTES AND COMMENTS CNPS Conference: Rare and Endangered Plants Keynote speakers for the first CNPS conference on rare and endangered plants, scheduled for November 5-8, 1986, in Sacramento, are: Paul Ehrlich (Stanford University); Daniel Axelrod (University of California, Davis); Ray Dasmann (University of California, Santa Cruz); Ed Hastey (Bureau of Land Management); Zane Smith (U.S. Forest Service); Linda McMahan (World Wildlife Fund, U.S.); Faith Campbell (Nat- ural Resources Defense Council); and Christopher Stone (University of Southern California). The conference is co-sponsored by the Department of Fish and Game, the U.S. Fish and Wildlife Service, the Bureau of Land Management, the California Botanical Society, The Nature Conservancy, Rancho Santa Ana Botanic Garden, Pacific Gas and Electric, Southern California Edison, and Jones and Stokes Associates. For more information: James Nelson, Conference Coordi- nator, California Native Plant Society, 909 12th Street, Suite 116, Sacramento, CA 95814. 1987 Tours of Interest Gardens of Scotland and Northern England June 26-July 17, 1987 A Pacific Horticulture tour with George Waters. Chateaux and Gardens of France June 11-27, 1987 A Friends of Filoli tour with Timmy Gallagher. For independent travel and tours to every destination contact: 407 Jackson Street, Room 205 (415) 981-6640 San Francisco, CA 94111 Joan Curry Susan M. Smith 36 California Chaparral: Paradigms Reexamined The Natural History Museum of Los Angeles County is opening a new permanent exhibit "The chaparral — a story of life from fire," and is sponsoring a symposium, "California chaparral—paradigms reexamined," on November 7-8, 1986. The symposium will cover fire and demography, physiology, structure and function, and community structure. Featured speakers will be Daniel I. Axelrod, U.C. Davis, "The origins of chaparral: historical development;" Sherwin Carlquist, Rancho Santa Ana Botanic Garden, "Woody Anatomy: a key to chaparral adaptation;" and Harold A. Mooney, Stanford University, "Physiology of chaparral plants: new understand- ings." Registration information is available from Sterling Keeley or Don Reynolds at the Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, (213) 744-3379. Post-Fire Ryegrass Seeding "If you have believed for many years that seeding annual ryegrass is cost-effective for erosion control on wildfire burns in Southern California, then you may have been throwing your money away." This is the preliminary conclusion of a cooper- ative administrative study by the USDA Forest Service, Cleve- land and Angeles National Forests, and the U.C. Cooperative Extension Service. The study compared soil loss (erosion) from various seeding rates of annual ryegrass and natural plant regeneration on a 1984 wildfire burn in north San Diego County. On this wildfire burn, known as Aguanga Fire, even the high seeding rate of forty pounds of ryegrass per acre provided no significant protection against soil loss over that provided by natural regeneration on this previously brush-covered site. Many ecologists and scientists in Southern California have questioned the utility of this common practice of "throwing" annual ryegrass on Southern California wildfire burn sites. Due to environmental conditions in Southern California, including highly variable rainfall, steep slopes, and poor and shallow soils, annual ryegrass—which was developed as a lawn and pasture plant for conditions of adequate moisture and fertility—does not seem to be a good candidate for erosion control on wildfire burn sites in Southern California. Grow- ing conditions in Southern California chaparral are not con- ducive to quick and adequate establishment of annual ryegrass cover, since normal rains occur during the cooler part of the year following summer and fall wildfires. More information can be obtained from Gene Blakenbaker, Cleveland National Forest, (619) 445-6235, or Walter Graves, U.S. San Diego Cooperative Extension Service, (619) 565-5376. Strybing Arboretum's Mediterranean and Native Plant Gardens Strybing Arboretum in San Francisco's Golden Gate Park is devoting substantial acreage to gardens of plants from the world's five Mediterranean climates, i.e., California, the Med- iterranean basin, central Chile, Cape Province (South Africa), and south and southwest Australia. The five gardens will be contiguous so that comparison and demonstration of paral- lel development of the floras of these similar climatic regimes can be made. The Arthur Menzies Garden of California Native Plants, planted in the early 1960s, has been redesigned by landscape architect Ron Lutsko. Most established woody plants will be left in place, major paths will be realigned, two rock gardens will be established, and an interpretation center will be added. Theme plants serving to unite the garden are gumweed (Grindelia stricta subsp. venulosd), Douglas iris, buckwheat (Eriogonum arborescens), California fuchsia (Zauschneria cana), manzanita {Arctostaphylos stanfordiana), Ceanothus 'Julia Phelps', and madrone. Fundraising is now underway, with the goal of beginning construction this fall. Tax-deductible contributions are needed and may be sent to Strybing Arboretum Society, Ninth Avenue and Lincoln Way, San Francisco, CA 94122. BOOK REVIEW Flowering Plants: The Santa Monica Mountains, Coastal and Chaparral Regions of Southern California, by Nancy Dale. 1986. 239 pages. Capra Press, Santa Barbara, California. Available from CNPS, 6223 Luban Avenue, Woodland Hills, CA 91367. $14.95 soft cover (includes shipping and tax). Finally, a wildflower guide has been published on the plants of the Santa Monica Mountains that is useful to both the ama- teur and professional. No longer does one need to carry the cumbersome Munz, Flora of Southern California, or the scarce Raven and Thompson, Flora of the Santa Monica Mountains, to learn the plants of this region. This new, almost pocket-sized book makes it easy to identify the majority of plants that one might come across during a hike through these mountains. Flowering Plants has an attractive cover photograph and is well-organized with alphabetical arrangement of the plants according to plant families and genera. In addition, there is a quick reference index that groups species by flower color. The introductory pages supply the reader with some simple defi- nitions that will aid in the recognition of most species. The introduction also provides a useful ecological and geological background of the area for the beginning wildflower enthusiast. The book describes over 250 species, roughly one- third of all those found in the Santa Monica Mountains, and most of these are depicted by a color photograph. Each spe- cies covered in the book has an accompanying photograph or drawing, the scientific and common names, a brief descrip- tion of the plant, including key identifying characteristics and avoiding much of the botanical jargon, flowering times, dis- tribution within the Santa Monica Mountains, the meaning of each scientific name, and miscellaneous information on edi- bility, Indian usage, historical facts, or horticultural advice. The final chapters of the book list parks and botanical gardens in the area, as well as nature clubs interested people may join. There are maps of the Los Angeles vicinity and a smaller-scale CALIFORNIA FLORA NURSERY Natives & Mediterraneans ? Wholesale & Retail Somers & D Street (P.O. Box 3) Fulton, CA 95439 Just north of Santa Rosa 707-528-8813 NOW AVAILABLE A Flora Of San Diego County, California By R. Mitchel Beauchamp, M. Sc. An up-to-date inventory of the native and adventive plants of this southwestern-most region of the Continen- tal United States. The 241 page reference contains a sec- tored vegetation map of the county with discussion of plant communities and the rich floral diversity of the area. The 1841 native and 469 non-native plant taxa are listed with their known locations, flowering periods, elevational ranges and habitat regions within the county. Identification keys allow field use of the book. Soft cover edition (Lexotone cover for long wear).............................$22.95 Hard cover edition........................$28.95 County Vegetation Map — unsectored (on durable Dupont TYVEK) 15" by 17'/2" rolled....................$3.25 folded flat................$2.25 Add 6% tax for California buyers plus shipping of $2 per book and $1 per map Available from SWEETWATER RIVER PRESS Post Office Box 985 • National City, CA 92050-0220 Flowering Plants by Nancy Dale .O^v- .yv^ \ narrative botanical history of the Santa Monica Mountains and other coastal and chaparral regions of Southern California, illustrated with 200 color plates and 50 drawings. Plant lore includes Indian uses, ancient medicinal practices, recipes, and cultivation requirements. Send your check for $14.95 (includes shipping & tax), payable to California Native Plant Society, to: CNPS 6223 Lubao Avenue Woodland Hills, CA 91367 Proceeds from the sale of this book will be used for educational and interpretive materials within the Santa Monica Mountains National Recreation Area. This book made possible by a grant from the Santa Monica Mountains Conservancy. DISTRIBUTED TO TRADE BY CAPRA PRESS, SANTA BARBARA one of the Santa Monica Mountains, and finally, a short bib- liography and glossary. The photographs in general are excellent and are often suffi- cient to identify a plant without consulting the description. Most of the commonly encountered species are included. Larger genera such as Calochortus and Phacelia are given a more thorough treatment. The majority of biological terms are precise and unambiguous, although there are a few places where definitions are unclear (for example, the difference between genus and family in the preface or the use of glabrous for smooth, defined as naked or without hairs). The author and her support from the Santa Monica Moun- tains chapter of the California Native Plant Society are to be congratulated on the completion of an attractive and highly useful wildflower guide. In addition, Marianne Wallace has provided many excellent illustrations, and there is a string of sixteen photographers who have supplied superb pictures. CNPS played a significant role in supporting the production of this book. It is hoped that Flowering Plants will be the first in a series of regional wildflower guides sponsored by CNPS. With the success of this book, CNPS should be encouraged to proceed with the production of photographic wildflower guides for the more important floristic areas of the state. Flowering Plants is recommended to anyone with an inter- est in learning about the native plants of the Santa Monica Mountains. Here is an easy-to-use book that will give the reader a lot or a little information, as desired. The more one learns about native plants, the more one will appreciate the importance of preserving the natural beauty of the Santa Monica Mountains. Daryl Koutnik Huntington Botanical Gardens BOOKS RECEIVED The Vascular Plants of Snow Mountain, North Coast Ranges, California, by L.R. Heckard and J.C. Hickman. Volume 43, 1985. 42 pages. An annotated list of the 517 native and introduced species known to grow above 1,500 m. Reprinted and available from the Wasmann Journal of Biology, Univer- sity of San Francisco, San Francisco, CA 94117. $4.00 The Different Forms of Flowers on Plants of the Same Spe- cies, by Charles Darwin. 1888, reprinted in 1986. 352 pages. In the new foreword to this work, Herbert Baker claims it is not only a botanical classic but is still, one hundred years later, a major source of correct information on the reproductive biology of plants. Available from the University of Chicago Press, 5801 S. Ellis Ave, Chicago, 60637. Emil Haury's Prehistory of the American Southwest, compiled by J.J. Reid and D.E. Doyel. 1986. 505 pages. An anthology of Haury's career and the overlapping advances of archaeol- ogy which have led to Haury's theories on prehistoric migra- tion and settlement patterns. Available from the University of Arizona Press, 1615 East Speedway, Tuscon, Arizona 85719. $45 clothbound. 38 Systematic* and Evolution of Cordylanthus, (Scrophulariaceae-Pedicularieae), by T.I. Chuang and L.R. Heckard. 1986. 105 pages. Volume 10 in Systematic Botany Monographs, The American Society of Plant Taxonomists. Available from the University of Michigan Herbarium, North University Building, Ann Arbor, Michigan 48109. The Earth Manual: How to Work on Wild Land without Taming It, by Malcolm Margolin. 1975, revised 1986. 237 pages. The author has drawn on his experiences in the East Bay Regional Park and has created a must for park personnel and school gardeners. Available from Heydey Books, Box 9145, Berkeley, CA 94709. $8.95 soft cover. CLASSIFIED ADS Classified ad rate: 50 cents per word, minimum $12; payment in advance. Address advertising inquiries and copy to: Nancy Dale, 500 W. Santa Maria #7, Santa Paula, CA 93060. Nurseries and Seeds YERBA BUENA NURSERY, 19500 Skyline, Woodside, California 94062. (415) 851-1668. Specializes in California native plants and native and exotic ferns. Open every day except holidays, 9-5. Owner Gerda Isenberg. WILDFLOWER seed catalog. Beautifully illustrated, over 60 wild- flowers are described in this useful reference booklet, including many California favorites. Send $1.00 for catalog and price list. Moon Moun- tain (FR), Box 34, Morro Bay, CA 93442. CALIFORNAI NATIVE PLANTS AND SEED: Available through Theodore Payne Foundation Nursery. Wildflower seed varieties and blends also available mail order. Please write or call for information. Send long SASE to Theodore Payne Foundation, Box F, 10459 Tux- ford Street, Sun Valley, Ca. 91352. (818) 768-1802. Nursery is open Tuesday through Saturday 8:30-4:30. Services EXPERT PROPERTY CARE. Land, flora, structures, administra- tion, ecologically handled. Permanent position sought. Will live on- site. Capable. L.S., P.O. Box 761, Ojai, CA 93023. Publications A TREAT FOR PLANT LOVERS, Pacific Horticulture is the West's own gardening magazine. Handsomely printed, excellent color photo- graphs. Quarterly, $12 year. P.O. Box 485, Berkeley, CA 94701. DESERT PLANTS describes the fascinating plant life of the world's arid regions. Published quarterly by the University of Arizona for the Boyce Thompson Southwestern Arboretum at Superior. $15/year for individuals, $20/year for organizations. P.O. Box 3607, College Sta- tion, Tucson AZ 85722. THE FOUR SEASONS, occasional journal of the Regional Parks Botanic Garden, founded by celebrated writer-conservationist James Roof, the only journal devoted to California native plant botany and horticulture presenting both technical and popular articles in every issue. $10 for 4 issues. Regional Parks Botanic Garden, Tilden Regional Park, Berkeley, CA 94708. (415) 841-8732. A FLORA OF THE TAHOE BASIN, NEIGHBORING AREAS, and SUPPLEMENT. Gladys L. Smith, 1983. Published by The Wasmann Journal of Biology, University of San Francisco. $10.85, ppd. Avail- able from the author, 730 28th Avenue, San Francisco, CA 94121. CNPS Conference Rare and Endangered Plants Their Conservation and Management m Location: Capitol Plaza Holiday Inn, Sacramento Proceedings will be dedicated to G.L. Stebbins for his lifetime commitment to the study and preser- vation of California native flora. Topics: Inventory Skills Impact Assessment Restoration/Revegetation Population Dynamics Legal Protection Conservation Activities Role of Botanic Gardens To register: Send check to CNPS Rare Plant Conference 909 12th Street, Suite 116 Sacramento, CA 95814 Registration $60 regular, $35 student or retirees (Early response advised as space is limited and early registration heavy.) 39 DESERT LIVING COLOR NOTECARDS 24 assorted with envelopes - $6.95. MOCKELS DESERT FLOWER NOTEBOOK Soft Cover—Autographed 2 Indexes — Beautifully Illustrated —$9.95. MOCKEL STUDIO, 5686 The Plaza, Twentynine Palms, California 92277. NOTECARDS from original watercolors of wildflowers. Welcome gifts and unique wedding invitations. Fourteen designs; envelopes, tax and shipping inc., $12. Bulk discounts. Fairlee Ltd., P.O. Box 1223, Healdsburg, CA 95448. BEAUTIFUL CALIFORNIA wildflower notecards made of original photographs, envelopes included. $1.50 each plus Cal. state tax. Send for list of wildflowers available. Sonja Wilcomer, P.O. Box 60985, Palo Alto, CA 94306. NOTES ON CONTRIBUTORS Wayne Borth, a student of Dr Kummerow, recently received his masters degree at San Diego State University and plans to attend the University of Hawaii for a PhD degree in phytopathology. James A. Brass is a forester and remote sensing specialist, National Aeronautics and Space Administration, Ames Research Center, Ecosystem Science and Technology Office. Jean SmilingCoyote is a professional photographer who has avidly followed the post-fire floral displays in the Santa Monica Mountains, notably the 1982 42,000 acre fire that destroyed the M.A.S.H. set in Malibu Creek State Park. Anthony T. Dunn is a botanist and fire ecologist for the U.S.D.A. Forest Service and a former contributor to Fremontia. Melanie Florence has worked for BLM as range technician and botanist and now follows the fire patterns at the Pinnacles as she lives close by with her young family. Captain Scott Franklin is vegetation management program director for the Los Angeles County Fire Department. Jon Keeley is associate professor of biology at Occidental Col- lege. He has done research on chaparral fire ecology since 1971. Sterling Keeley is associate professor of biology at Whittier College. She has directed the California chaparral exhibit and November symposium at the Los Angeles Museum. Jochen Kummerow is professor of botany at San Diego State University. His research focuses on chaparral and arctic tundra ecosystems. Philip J. Riggan conducts fire and chaparral research for the USDA Forest Service, Pacific Southwest Forest and Range Experiment Station. He is stationed at the Forest Fire Labora- tory, Riverside. Philip Rundel is professor of biology and chief of environ- mental biology in the Biomedical and Environmental Science Laboratory at the University of California, Los Angeles. He has done research on chaparral for fifteen years and lives in the midst of chaparral in the Santa Monica Mountains. Nevin Smith is the proprietor of the Wintergreen Wholesale Nursery in Watsonville and an active participant in the Native Plant Study Group of the California Horticultural Society. Paul Zedler is professor of biology at San Diego State Univer- sity. His research interests are the population ecology of chap- arral plants and the restoration and management of vernal pools. TABLE OF CONTENTS Structure and Function in California Chaparral by Philip W. Rundel Mycorrhizal Associations in Chaparral 11 by Jochen Kummerow and Wayne Borth Closed-Cone Conifers of the Chaparral 14 by Paul H. Zedler Chaparral and Wildfires 18 by Jon E. Keeley and Sterling C. Keeley Flowers of the Phoenix 22 by Jean SmilingCoyote Fire and Chaparral Management at the Chaparral/Urban Interface 28 by Philip J. Riggan, Scott Franklin and James A. Brass Plant Succession on Prescribed Burn Sites at Pinnacles National Monument 31 by Melanie Florence Growing Natives: More from the Chaparral 34 by Nevin Smith Notes and Comments 36 Book Review 37 Books Received 38 Forwarding and Address Correction Requested ^ « n 5! ° s» n ^ — i KI 3. (•> 5 P !* Z > E. <-2^ C/l o o# n' ** -< Nonprofit Org. U.S. Postage PAID San Francisco, CA Permit No. 10318 40