Index of Species Information

SPECIES:  Pinus torreyana


Introductory

SPECIES: Pinus torreyana
AUTHORSHIP AND CITATION : Esser, Lora L. 1993. Pinus torreyana. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

ABBREVIATION : PINTOR SYNONYMS : NO-ENTRY SCS PLANT CODE : PITO COMMON NAMES : Torrey pine Santa Rosa Island Torrey pine Del Mar pine Soledad pine TAXONOMY : The currently accepted scientific name of Torrey pine is Pinus torreyana Parry. There are no recognized varieties or forms. There are two recognized subspecies [14,34]: Pinus torreyana ssp. insularis Haller Pinus torreyana ssp. torreyana. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : Both subspecies of Torrey pine are listed in Category 1B by the California Native Plant Society: rare or endangered in California [41].


DISTRIBUTION AND OCCURRENCE

SPECIES: Pinus torreyana
GENERAL DISTRIBUTION : Torrey pine is the rarest pine in North America [9]. The natural distribution of Torrey pine consists of two disjunct populations. The mainland population, in and near the Torrey Pines State Reserve (TPSR), is confined to the low coastal bluffs flanking the Soledad Valley in San Diego County, California. It consists of approximately 7,000 trees [7,22]. The other population occurs on Santa Rosa Island off the coast of southern California, 175 miles (280 km) northwest of the mainland population [7,13,22]. This population consists of approximately 2,000 trees [20]. ECOSYSTEMS : FRES34 Chaparral - mountain shrub STATES : CA BLM PHYSIOGRAPHIC REGIONS : 3 Southern Pacific Border KUCHLER PLANT ASSOCIATIONS : K033 Chaparral K035 Coastal sagebrush SAF COVER TYPES : NO-ENTRY SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : The Torrey pine forest is the only southern California coastal pine forest [26,33]. Torrey pine part of the California closed-cone pine forests [37,41]. These forests merge with coastal sage scrub, chaparral, dune scrub, and coastal salt marsh [37]. On Santa Rosa Island, Torrey pine is a member of the Torrey pine woodland. This community ranges from a monotypic assemblage of Torrey pine with a litter understory to more open stands that resemble woodlands mixed with California scrub oak (Quercus dumosa) and shrubs [5]. Torrey pine is listed as a codominant or dominant species in the following publications: Plant communities of Santa Rosa Island, Channel Islands National Park [5] The closed-cone pines and cypress [37] Preliminary descriptions of the terrestrial natural communities of California [41] Plant communities of southern California [42]. Some species commonly associated with Torrey pine include chamise (Adenostoma fasciculatum), California sagebrush (Artemesia californica), toyon (Heteromeles arbutifolia), lemonadeberry (Rhus integrifolia), California scrub oak, mule fat (Baccharis viminea), bush poppy (Dendromecon rigida), California encelia (Encelia californica), white sage (Salvia apiana), black sage (S. mellifera), saw-toothed goldenbush (Haplopappus squarrosus), Costa Baja manzanita (Arctostaphylos glandulosa ssp. crassifolia), Santa Rosa Island manzanita (A. confertiflora), California buckwheat (Eriogonum fasciculatum), warty-stem ceanothus (Ceanothus verrucosus), feltleaf ceanothus (C. arboreus), western yarrow (Achillea millefolium), sea fig (Carpobrotus chilensis), iceplant (Mesembryanthemum spp.), Indian paintbrush (Castilleja spp.), monkeyflower (Mimulus spp.), California poppy (Eschscholzia californica), sedge (Carex globosa), oniongrass (Melica imperfecta), bent grass (Agrostis spp.), slender wild oat (Avena barbata), and purple cudweed (Gnaphalium purpureum).

MANAGEMENT CONSIDERATIONS

SPECIES: Pinus torreyana
IMPORTANCE TO LIVESTOCK AND WILDLIFE : Seeds of Torrey pine are eaten by birds, rodents, and other mammals. The dusky-footed and desert woodrats consume large quantities of Torrey pine seeds and may greatly reduce their numbers in the seedbank [26]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : NO-ENTRY COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : Torrey pines are planted on wildlands and disturbed sites in San Diego, California. Near Point Loma, San Diego, they provide wildlife habitat and protect existing coastal sage scrub shrubs [19]. OTHER USES AND VALUES : Torrey pine is widely planted as an ornamental and has been evaluated as a commercial species in Kenya, Australia, and New Zealand [26]. OTHER MANAGEMENT CONSIDERATIONS : The Torrey pine population in TPSR consists of large, mature individuals; seedlings and saplings are infrequent [40]. Given the low rate of seedling establishment and survival in the recent past, stand age of Torrey pine will continue to increase within the TPSR [26]. Cattle grazing has significantly reduced the amount of native shrub cover within Torrey pine stands on Santa Rosa Island. The average amount of open ground on four transects on Santa Rosa Island is about 78 percent compared to 30 percent on the mainland. Seedling establishment is higher on Santa Rosa Island than on the mainland [26]. Because of low genetic variability, Torrey pine has little capacity to respond to change through natural selection. Native populations should be managed to maintain the maximum number of trees possible to minimize the chance of catastrophic loss [21]. Both the island and mainland populations of Torrey pine are threatened by air pollution. The mainland population is adjacent to densely populated areas that generate extreme amounts of air pollution. The island population is threatened by seasonal easterly Santa Ana winds carrying air with high concentrations of ozone and other pollutants from the Los Angeles Basin [8,22]. In 1988, a bark beetle (Ips paraconfusus) infestation occurred at TPSR. By 1990, 12 percent of the adult trees had been killed. In 1991, the U.S. Forest Service utilized synthetic pheromones to lure ips beetles into traps placed on trees. Nine weeks after placement of the traps 130,000 beetles were captured [2]. Only one additional tree was attacked after the trapping began. The number of trapped beetles eventually fell to about 100 per week [2].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Pinus torreyana
GENERAL BOTANICAL CHARACTERISTICS : Torrey pine is a native, slow-growing tree endemic to California [25,30]. It grows from 25 to 60 feet (7.5-18 m) tall, but is usually around 40 feet (12 m) in height [17,33]. The mature crown is open and rounded with many large branches [14]. The needles are in fascicles of 5 and are 8 to 12 inches (20-30 cm) long [16]. The bark is rough and flaky [16]. Cones are large, 4 to 6 inches (10.2-15.2 cm) wide, and long. They are harder and heavier than most other pine cones [33]. Torrey pine taproots may reach 25 feet (7.5 m) into sandstone, and lateral roots can extend up to 225 feet (67.5 m) from the trunk [9]. The oldest Torrey pines are about 150 years old [21]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Torrey pine regenerates sexually. It does not reproduce naturally by vegetative methods. Seed production and dissemination: Torrey pines begin to produce seed when they are 12 to 18 years old. Torrey pine exhibits delayed seed dispersal, a pattern of seed release intermediate between open- and closed-cone species. In the TPSR, Torrey pine cones begin to open when seeds are mature, but seed fall continues for up to 13 years after cone maturity. Over 76 percent of available seeds were in cones 1 or more years after seed maturity [27]. Seed release accelerates through the fourth year when cones retain 22 percent of seeds, and then levels off or slowly declines [27]. Over 15 percent of the original seed is retained 11 years following cone maturity [26]. At age 14, cones are mostly open but still retain about 10 percent of seed [14]. Torrey pines on Santa Rosa Island may release seed more rapidly than those in the TPSR [26]. Seed viability decreases with cone age, but seeds at least partially exposed for 10 years remain viable [27]. Predispersal loss of seed is high in Torrey pine. Before dispersal, 6.8 percent of seed is lost to arthropod seed predators within the cone and 4.6 percent of seed has already germinated. Germination of seed in the cone is unique to Torrey pine in the genus Pinus [26,27]. The seed of Torrey pine is nearly wingless; wind dispersal is negligible. Birds such as scrub jays aid in seed dissemination [9,20]. Seedling development: Cold stratification periods of 30 to 90 days at 33 to 41 degrees Fahrenheit (.56-5 deg C) are recommended for rapid and complete germination [17]. Seedling mortality is largely a function of water stress and is highest in July and August. Seedling establishment increases with disturbance such as fire. Very few seedlings are currently survive to reproductive age [26]. SITE CHARACTERISTICS : Torrey pine has adapted to a harsh environment of poor soils and little moisture [33]. The climate is maritime with low winter rainfall and frequent fog [40]. The species occurs in scattered groves or is widely dispersed on ridgetops, slopes, and gullies. It is also found in coastal highlands, canyons, and mesas [4,16]. It grows in open, shallow, humus-poor, sandy soils [33,40]. Torrey pine is found at elevations of 200 to 500 feet (60-150 m) [13]. SUCCESSIONAL STATUS : Facultative Seral Species Torrey pine is shade tolerant. Approximately 90 percent of Torrey pine seedlings are found under adult trees [26]. SEASONAL DEVELOPMENT : Torrey pine is monoecious. Cones are pollinated from January to March and reach maturity in the summer two and a half years later [26]. Cone opening initiates when seeds are mature [14]. Seed dispersal begins in September after cone-ripening [16,17].

FIRE ECOLOGY

SPECIES: Pinus torreyana
FIRE ECOLOGY OR ADAPTATIONS : Torrey pine exhibits delayed seed dispersal which is beneficial in the event of fire [11,28]. Some seeds are released immediately after fire and exploit postfire conditions such as sterilized soil, reduced competition from other species, and the absence of seed-eating rodents [11]. Other seeds are released gradually and increase Torrey pine stocking. Cones can be retained on trees and release viable seed for up to 15 years [28]. McMasters [27] stated that delayed seed dispersal of Torrey pine and reduced serotiny of other coastal and insular conifers may arise form the same cause: a fire pattern in which large scale, intense crown fires have alternated with long intervals in which ther were no fires at all or in which there were only low-severity surface fires. POSTFIRE REGENERATION STRATEGY : Tree without adventitious-bud root crown Crown residual colonizer (on-site, initial community) Secondary colonizer - off-site seed

FIRE EFFECTS

SPECIES: Pinus torreyana
IMMEDIATE FIRE EFFECT ON PLANT : Torrey pine is fire-intolerant [40]. Low-severity fires will kill trees up to 21 inches (52 cm) dbh even if no crown damage is sustained [40]. Severe fires kills trees of all sizes [26]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Seed drop is substantial after crown fires [26,40]. Establishment of seedlings from stored seeds released by fire-killed trees has been confirmed after both wildfires and prescribed fires [39]. An arson fire in TPSR occurred on July 12, 1972. Ninety-three mature trees were killed on 11.3 acres (4.8 ha). Seedling establishment occurred in postfire year 1 [27]. In May of 1979, 220 saplings and seedlings were found in the burned area. Juvenile tree density was two and a half times greater than the prefire mature tree density [26,27]. On November 6 and 7, 1978, 31,204 square feet (2,900 sq m) were burned in the TPSR under controlled conditions. Results on Torrey pine regeneration were inconclusive. However, prescribed fires in the spring of 1984 and winter of 1985, which killed 19 trees and 17 saplings, did promote seedling establishment. In January 1986, a total of 201 seedlings were found in the burned area [40]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Torrey pine may be declining in the TPSR because past fire-exclusion policies have created an unnatural setting. Infrequent, severe fires are best for Torrey pine seedling establishment, although disturbance is not essential to seedling establishment [26]. According to Zedler and others [40], maintaining a natural system in the TPSR may require that it be allowed to burn to the ground every century [40]. If fires occur in a Torrey pine population at intervals shorter than 12 to 18 years, (when saplings begin to produce cones), they could seriously impair the ability of the population to survive [26].

References for species: Pinus torreyana


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