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Overview

Distribution

Knobcone pine is the most widely distributed of the West Coast
closed-cone species. Discontinuous populations occur from southwestern
Oregon south through the Klamath, Cascade, and Coast ranges and the
Sierra Nevada. Stands in the South Coast Ranges are widely disjunct,
occurring in the Santa Ana and west San Bernadino mountains, at Cuesta
Pass, San Luis Obisbo County, and near Encinada, Baja California
[14,21,32,44].
  • 21. Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. 375 p. [2952]
  • 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 32. Minnich, Richard A. 1987. The distribution of forest trees in northern Baja California, Mexico. Madrono. 34(2): 98-127. [6985]
  • 44. Vogl, Richard J.; Armstrong, Wayne P.; White, Keith L.; Cole, Kenneth L. 1977. The closed-cone pines and cypress. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley and Sons: 295-358. [7219]

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Regional Distribution in the Western United States

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains

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Occurrence in North America

CA OR MEXICO

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Localities documented in Tropicos sources

Pinus attenuata Lemmon:
United States (North America)
Mexico (Mesoamerica)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Physical Description

Morphology

Description

Shrubs or trees to 24m; trunk to 0.8m diam., usually straight; crown mostly narrowly to broadly conic. Bark purple-brown to dark brown, shallowly and narrowly fissured, with irregular, flat, loose-scaly plates, on upper sections of trunk nearly smooth. Branches ascending; twigs slender, red-brown. Buds ovoid to ovoid-cylindric, dark red-brown, aging darker, ca. 1.5cm, resinous; scale margins fringed, apex attenuate. Leaves 3 per fascicle, spreading or ascending, persisting 4--5 years, (8--)9--15(--20)cm ´ (1--)1.3--1.8mm, straight or slightly curved, twisted, yellow-green, all surfaces with fine stomatal lines, margins serrulate, apex abruptly conic-subulate; sheath (1--)1.5--2cm, base persistent. Pollen cones ellipsoid-cylindric, 10--15mm, orange-brown. Seed cones maturing in 2 years, serotinous, long-persistent, remaining closed for 20 years or more, or opening on burning, in whorls, hard and heavy, very asymmetric, lanceoloid before opening, ovoid-cylindric when open, 8--15cm, yellow- or pale red-brown, stalks to 1cm; apophyses toward outside base increasingly elongate, mammillate or raised-angled-conic, downcurved near base, scarcely raised on branchlet side, rhombic; umbo central, low-pyramidal, sharp, upcurved. Seeds compressed-oblique-obovoid; body ca. 6--7mm, nearly black; wing narrow, to 20mm. 2 n =24.
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Description

More info for the term: tree

Knobcone pine is a rapidly growing, native tree from 20 to 40 feet (6-12
m) tall and 13.5 to 23 inches (34-58 cm) in d.b.h. [13,41]. The crown
is dense and broad when young, becoming open when mature. Trees
typically have multiple trunks with thin bark [36,42]. Excavtion of
knobcone pine roots in the Santa Ana Mountains showed that vertical
roots grew to bedrock in the shallow soil. Average root depth was 10.4
inches (26.2 cm) [41]. Roots in less restrictive sites are reported as
"wide and deep" [36].

Trees produce female cones in groups of four or five, all firmly
attached to stout branches in a tight whorl. The asymmetrical cones are
arched in configuration, as are the individual ovuliferous scales.
Cones remain closed and attached to the tree for life [40,48]. The
enclosed seeds are small and light, with thin seed coats and long seed
wings [15,41]. The lifespan of knobcone pine is relatively short. Some
trees reach ages of 75 to 100 years [14], but in a typical 60-year-old
stand, over half the pines are dead [41].
  • 15. Keeler-Wolf, Todd. 1986. An ecological survey of the proposed Stone Corral - Josephine Peridotite Research Natural Area (L. E. Horton - Darlingtonia Bog Research Nat. Area) on the Six Rivers National Forest, Del Norte County, California. Purchase order # 40-9AD6-5-907. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Intermountain Fire Sciences Laboratory, Missoula, MT. 69 p. [12307]
  • 36. Preston, Richard J., Jr. 1948. North American trees. Ames, IA: The Iowa State College Press. 371 p. [1913]
  • 13. Horton, Jerome S. 1949. Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest]
  • 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 40. Vogl, Richard J. 1967. Fire adaptations of some southern California plants. In: Proceedings, Tall Timbers fire ecology conference; 1967 November 9-10; Hoberg, California. No. 7. Tallahassee, FL: Tall Timbers Research Station: 79-109. [6268]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]
  • 42. Vogl, Richard J. 1976. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 77-98. [4230]
  • 48. Zedler, Paul H. 1986. Closed-cone conifers of the chaparral. Fremontia. 14(3): 14-17. [18648]

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Physical Description

Tree, Shrub, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots 3-dimensional, Buds resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins finely serrulate (use magnification or slide your finger along the leaf), Leaf apex acute, Leaves > 5 cm long, Leaves < 10 cm long, Leaves yellow-green above, Leaves yellow-green below, Leaves not blue-green, Needle-like leaves somewhat rounded, Needle-like leaves twisted, Needle-like leaf habit erect, Needle-like leaves per fascicle mostly 3, Needle-like leaf sheath persistent, Twigs glabrous, Twigs viscid, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones > 5 cm long, Seed cones bearing a scarlike umbo, Umbo with obvious prickle, Bracts of seed cone included, Seeds black, Seeds winged, Seeds unequally winged, Seed wings prominent, Seed wings equal to or broader than body.
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Stephen C. Meyers

Source: USDA NRCS PLANTS Database

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Diagnostic Description

Synonym

Pinus tuberculata Gordon 1849, not D.Don 1836
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is a fire successional tree with extremely persistent and serotinous seed cones on dry slopes in chaparral or similar vegetation, also on rocky outcrops of serpentine with little other plant growth. In the northern part of its range, where trees grow somewhat taller, it is often mixed with several species of oak (Quercus spp.) and with Cupressus sp. In the U.S.A. its altitudinal range is from 300-1,200(-1,700) m a.s.l. In Mexico it is found mainly from 250-600 m a.s.l. and close to the coast. Phenology: Pinus attenuata disperses pollen in late March-April in most of its range.

Systems
  • Terrestrial
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Habitat characteristics

More info for the terms: cover, fresh, serpentine soils, shrub

The climate in which knobcone pine grows is mediterranean, characterized
by wet, mild winters and hot, dry summers. Fog drip often precipitates
heavily beneath pines during summer months in coastal regions,
ameloirating the effects of hot weather [41]. The pines grow at
elevations between sea level and 5,500 feet (1,676 m) [44].

Soil parent materials are usually of volcanic origin [43]; serpentine is
the most common substrate [18,29]. Soils are typically shallow, rocky,
infertile, ultramafic, acid, and/or dry. They may contain levels of
magnesium, chromium, nickel, and/or cobalt that are toxic to most plants
[44]. Calcium, nitrogen, and phosphorus are usually deficient [43].
Soil pH at a knobcone pine site in the Santa Ana Mountains was 5.0 [43].
Water-retaining capacity of knobcone pine soils are often favorable to
its growth. The average saturation percentage of serpentine soils is
nearly double that of adjacent chaparral [41]. Slope angles range
between 0 and 38 degrees but are most commonly steep and subject to
continual erosion. Knobcone pine communities often occur along fault
blocks where earthquake activity has produced fresh serpentine
escarpments [41].

Plant associates: Overstory associates not listed in Distribution and
Occurrence include Monterey pine, Coutler pine (Pinus coulteri), Digger
pine (P. sabiniana), sugar pine (P. lambertiana), shore pine (P.
contorta spp. contorta), bigcone Douglas-fir (Pseudotsuga macrocarpa),
Pacific madrone (Arbutus mensiesii), tanoak (Lithocarpus densiflora),
giant chinkapin (Chrysopelis chrysophylla), incense-cedar (Libocedrus
decurrens), Pacific yew (Taxus brevifolia), tecate cypress (Cupressus
forbesii), Santa Cruz cypress (C. abramsiana), and MacNab cypress (C.
macnabiana) [26,27,28,44].

Some shrub associates are Eastwood manzanita (Arctostaphylos
glandulosa), pinemat manzanita (A. nevadensis), chamise, chaparral
whitethorn (Ceanothus leucodermis), wartleaf ceanothus (C. papillosus
var. rowaenus), wedgeleaf ceanothus (C. cuneatus), leather oak (Quercus
durata), chaparral currant (Ribes malvaceum var. viridifolium), Sargent
cypress (Cupressus sargentii), chaparral pea (Pickeringia montana), and
huckleberry (Vaccinium spp.) [6,14,42,44,46].

Ground cover associates include Carey balsamroot (Balsamorhiza
deltoidea), Hooker balsamroot (B. hookeri), fire reedgrass
(Calamagrostis koeleroides), houndstongue hawkweed (Hieracium
cynoglossoides var. nudicaule), big deervetch (Lotus crassifolius),
showy phlox (Phlox speciosa), and brome grasses (Bromus spp.) [14,41,46].
  • 6. Gardner, Robert A. 1958. Soil-vegetation associations in the redwood - Douglas-fir zone of California. In: Proceedings, 1st North American forest soils conference; [Date of conference unknown]
  • 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 18. Kruckeberg, Arthur R. 1984. California serpentines: flora, vegetation, geology, soils and management problems. Publications in Botany Volume 48. Berkeley, CA: University of California Press. 180 p. [12482]
  • 26. McDonald, Philip M. 1990. Pseudotsuga macrocarpa (Vasey) Mayr bigcone Douglas-fir. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 520-526. [13412]
  • 27. McDonald, Philip M.; Laacke, Robert J. 1990. Pinus radiata D. Don Monterey pine. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 433-441. [13401]
  • 28. McKee, Arthur. 1990. Castanopsis chrysophylla (Dougl.) A. DC. giant chinkapin. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Vol. 2. Hardwoods. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 234-239. [13962]
  • 29. McMillan, Calvin. 1956. The edaphic restriction of Cupressus and Pinus in the Coast Ranges of central California. Ecological Monographs. 26: 177-212. [11884]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]
  • 42. Vogl, Richard J. 1976. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 77-98. [4230]
  • 43. Vogl, Richard J. 1977. Fire: a destructive menace or a natural process?. In: Cairns, J., Jr.; Dickson, K. L.; Herricks, E. E., eds. Recovery and restoration of damaged ecosystems: Proceedings of the international symposium; 1975 March 23-25; Blacksburg, VA. Charlottesvile, VA: University Press of Virginia: 261-289. [10055]
  • 44. Vogl, Richard J.; Armstrong, Wayne P.; White, Keith L.; Cole, Kenneth L. 1977. The closed-cone pines and cypress. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley and Sons: 295-358. [7219]
  • 46. Whittaker, R. H. 1960. Vegetation of the Siskiyou Mountains, Oregon and California. Ecological Monographs. 30(3): 279-338. [6836]

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Key Plant Community Associations

More info for the terms: cover, shrubs

The knobcone pine community occupies a transitional position between
chaparral and woodland and higher elevation forests. Because of its
patchy distribution, it is usually surrounded by other communities. At
lower elevations, it is most often associated with chamise (Adenostoma
fasciculatum)-manzanita (Arctostaphylos spp.) communities and various
oak (Quercus spp.) woodlands. At higher elevations, it is associated
with a variety of coniferous communities (see SAF Cover Types) [44].
Within the knobcone pine community, the pines are usually widely spaced.
The community is sometimes described as woodland rather than as forest
[24]. On favorable sites, knobcone pine forms dense, even-aged stands
or dwarfed thickets. Understory herbaceous species are usually
fire-followers and endemics. Shrubs occur individually or in small
patches between pines. Mosaics of chaparral, woodland, knobcone pine,
and other coniferous forests sometimes occur due to topographical and
substrate differences [32,41,44].

Publications listing knobcone pine as a dominant species are as follows:

Vegetational types of the San Bernadino Mountains [14]
Vegetation of the San Bernadino Mountains [31]
A vegetation classification system applied to southern California [34]
Mixed evergreen forest [38]
Vegetation of the Siskiyou Mountains, Oregon and California [46]
An introduction to the plant communities of the Santa Ana and San
Jacinto Mountains [42]
The closed-cone pines and cypresses [44]
  • 31. Minnich, Richard A. 1976. Vegetation of the San Bernardino Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 99-124. [4232]
  • 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 24. McBride, Joe R. 1974. Plant succession in the Berkeley Hills, California. Madrono. 22(7): 317-380. [18874]
  • 32. Minnich, Richard A. 1987. The distribution of forest trees in northern Baja California, Mexico. Madrono. 34(2): 98-127. [6985]
  • 34. Paysen, Timothy E.; Derby, Jeanine A.; Black, Hugh, Jr.; [and others]
  • 38. Sawyer, John O.; Thornburgh, Dale A.; Griffin, James R. 1977. Mixed evergreen forest. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley and Sons: 359-381. [7218]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]
  • 42. Vogl, Richard J. 1976. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 77-98. [4230]
  • 44. Vogl, Richard J.; Armstrong, Wayne P.; White, Keith L.; Cole, Kenneth L. 1977. The closed-cone pines and cypress. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley and Sons: 295-358. [7219]
  • 46. Whittaker, R. H. 1960. Vegetation of the Siskiyou Mountains, Oregon and California. Ecological Monographs. 30(3): 279-338. [6836]

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Habitat: Plant Associations

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: shrub

K006 Redwood forest
K009 Pine - cypress forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest
K030 California oakwoods
K033 Chaparral
K034 Montane chaparral

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Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES27 Redwood
FRES28 Western hardwoods
FRES34 Chaparral - mountain shrub

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Habitat: Cover Types

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

215 Western white pine
229 Pacific Douglas-fir
231 Port-Orford-cedar
232 Redwood
233 Oregon white oak
234 Douglas-fir - tanoak - Pacific madrone
244 Pacific ponderosa pine - Douglas-fir
245 Pacific ponderosa pine
246 California black oak
247 Jeffrey pine
249 Canyon live oak
250 Blue oak - Digger pine
255 California coast live oak

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Habitat & Distribution

Fire successional on dry slopes and foothills of Sierra Nevada and the Cascade and Coast ranges; 300--1200m; Calif., Oreg.; Mexico in Baja California.
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Comments: On Sierra Juárez it grows at 250-1200 m altitude, rocky, gravelly-sandy soil, with winter anual rainfall of 600 mm aprox. Hot temperatures in the summer and snow and frezzing in the winter.

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General Ecology

Fire Management Considerations

More info for the term: litter

Fire is essential for the completion of knobcone pine's life cycle.
Cones of senescent or dead trees must be opened by fire to perpetuate
the groves before trees succumb and add the unopened cones to the
decomposing litter [40].
  • 40. Vogl, Richard J. 1967. Fire adaptations of some southern California plants. In: Proceedings, Tall Timbers fire ecology conference; 1967 November 9-10; Hoberg, California. No. 7. Tallahassee, FL: Tall Timbers Research Station: 79-109. [6268]

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Plant Response to Fire

Fire-opened cones remain attached to standing dead trees. Released seed
quickly germinates with late winter or early spring rains [47].
Seedlings continue to establish over a period of several years as cones
slowly open and release seeds. Aerial photographs taken at postfire
year 16 of a burn on Cerro Miracielo, Baja California, showed that
saplings had established throughout the burn [32].
  • 32. Minnich, Richard A. 1987. The distribution of forest trees in northern Baja California, Mexico. Madrono. 34(2): 98-127. [6985]
  • 47. Wright, Robert D. 1968. Lower elevational limits of montane trees. II. Environment-keyed responses of three conifer species. Botanical Gazette. 129(3): 219-226. [19180]

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Immediate Effect of Fire

More info for the terms: stand-replacing fire, surface fire

Crown fire kills knobcone pine of all size classes and vaporizes the
resin sealing their cones [13,41]. The effect of surface fires on
mature trees is undocumented. The thin bark, however, probably provides
little protection from all but low-severity surface fire. Saplings are
killed by surface fire. Fire is not a threat to young trees, however,
since the preceding stand-replacing fire has removed most of the fuel
load [30]. Cones are extremely fire resistant and are seldom consumed
by fire [41].
  • 13. Horton, Jerome S. 1949. Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest]
  • 30. Menke, John W.; Villasenor, Ricardo. 1977. The California Mediterranean ecosystem and its management. In: Mooney, Harold A.; Conrad, C. Eugene, technical coordinators. Proc. of the symp. on the environmental consequences of fire and fuel management in Mediterranean ecosystems; 1977 August 1-5; Palo Alto, CA. Gen. Tech. Rep. WO-3. Washington, DC: U.S. Department of Agriculture, Forest Service: 257-270. [4847]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]

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Post-fire Regeneration

More info for the terms: crown residual colonizer, root crown

Tree without adventitious-bud root crown
Crown residual colonizer (on-site, initial community)

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Fire Ecology

More info for the terms: cover, litter, tree

Knobcone pine is an obligate fire type with a strict closed-cone habit.
This adaptation, along with the general absence of animal agents that
might open cones, leaves the species dependent upon stand-replacing
crown fire for reproduction. Continued production and accumulation of
cones throughout the life of a tree assures that large quantities of
seed are released when fire opens cones. The open, multitrunked growth
form of knobcone pine promotes fire crowning [41].

Fire creates seedbed conditions favorable for germination and seedling
recruitment. It temporarily raises soil pH and increases soil nutrient
content, particularly phosphorus and nitrogen. A longer-term benefit of
fire to the species is the retrogressive role it plays in soil genesis.
By removing litter and ground cover vegetation, fire contributes to soil
erosion. Wind-felling of fire-killed trees results in further churning
up of nutrient-deficient soils. Most plant species cannot compete with
knobcone pine on such poor sites. The discontinuous nature of
serpentine prevents all the pines in an area from being killed by any
one fire [41].

Natural fires are probably less frequent in knobcone pine forests than
in other western closed-cone communities [25]. The infertile sites
where knobcone pine occurs support little undercover. Litter layers
are usually moderate [13]. A 20-year-old plantation in the San Dimas
Experimental Forest, southern California, produced 10.9 tons of forest
floor per acre (24.5 t/ha) [17]. The average interval between fires is
undocumented.
  • 13. Horton, Jerome S. 1949. Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest]
  • 17. Kittredge, Joseph. 1955. Some characteristics of forest floors from a variety of forest types in California. Journal of Forestry. 53(9): 645-647. [8176]
  • 25. McCune, Bruce. 1988. Ecological diversity in North American pines. American Journal of Botany. 75(3): 353-368. [5651]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]

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Successional Status

More info on this topic.

More info for the terms: competition, cover

Obligate Initial Community Species

Knobcone pine is a shade-intolerant pioneer species [9,36,40]. Fire
creates the conditions necessary for its continued survival. Old
knobcone pine stands, undisturbed for 60 or more years, will show signs
of invasion and competition from surrounding communities because the
resultant soil genesis and organic matter deposition have begun to
reduce or cover the restrictive barriers produced by serpentine [41].
In the absence of fire, knobcone pine is replaced by chaparral shrub
species at lower elevations and other conifers at higher elevations
[1,41].
  • 36. Preston, Richard J., Jr. 1948. North American trees. Ames, IA: The Iowa State College Press. 371 p. [1913]
  • 1. Agee, James K. 1991. Fire history along an elevational gradient in the Siskiyou Mountains, Oregon. Northwest Science. 65(4): 188-199. [16293]
  • 9. Hamilton, Ronald C. 1991. Single-tree selection method: An uneven-aged silviculture system. In: Genetics/silviculture workshop proceedings; 1990 August 27-31; Wenatchee, WA. Washington, DC: U.S. Department of Agriculture, Forest Service, Timber Management Staff: 46-84. [16562]
  • 40. Vogl, Richard J. 1967. Fire adaptations of some southern California plants. In: Proceedings, Tall Timbers fire ecology conference; 1967 November 9-10; Hoberg, California. No. 7. Tallahassee, FL: Tall Timbers Research Station: 79-109. [6268]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]

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Regeneration Processes

More info for the terms: shrubs, tree

Knobcone pine reproduction is controlled exclusively by fire; trees
occur in even-aged stands dating back to the last fire [42,43]. Unlike
other closed-cone species whose cones open with hot weather, upon
falling, or with age, unburned knobcone pine cones remain closed even
after trees have decayed and fallen. Cones are sealed with a hard resin
that requires high temperatures (average: 397 degrees Fahrenheit [203
deg C]) to liquefy, boil, and vaporize. Cone scales open gradually
following heating. The first seeds fall within 1 to 12 hours after
fire, when the ground has cooled. The arched scales continue to slowly
expand and drop seed for at least 4 postfire years. Scales partially
contract during periods of rain or other high relative humidity, but
resume expansion when relative humidity drops [41]. The small, light
seeds are wind dispersed. Knobcone pine has the greatest seed wing
length:seed size ratio of all the California closed-cone pines, allowing
for seed dispersal well beyond the edges of a fire [15]. Santa Ana
foehn winds, which blow during periods of low relative humidity, spread
seed for great distances. Seed wings from charred or scorched cones
often have fire-seared tips, causing seeds to fall in a slower spin than
seeds with unburned wing tips. Seeds with burned wings fall closer to
the parent tree. Birds aid in disseminating some seed. Steller and
scrub jays, attracted to partially opened cones, pound them heavily to
extract seeds. This results in additional seed dropping to the ground.
Hairy and downy woodpeckers may also jar seed from cones as they work
over burned stems in search of insects [41]. Western grey squirrel are
sometimes able to chew through unopened cones and may disseminate small
amounts of seed [42].

Trees begin seed production between 10 and 12 years of age. Average
production of trees over 20 years old is 176 cones per tree [41].
Limited tests show seed viability does not decline with age. Seeds
enclosed in cones for 27 [45] and 60 [41] years have proved viable.
Following release, seeds require cold stratification for 60 days [3,19].
Germinative capacity of seeds from mechanically opened cones has varied
from 57 to 91 percent [19,41]. Hot fire probably kills some seed.
Laboratory tests show that germination rates of seed from mechanically
opened cones are greater than those of cones opened by oven heat
treatment. Seeds may require a rise from normally low soil pH for
germination, and fire creates such a condition [41]. Knobcone pine
germinates earlier than other pines. Tested against Coulter and sugar
pines, it was the first of the three species to germinate [47].
Seedlings require bare mineral soil for establishment. They are drought
tolerant, with a strong tendency toward deep rooting [47]. Seedlings
establishing on fertile sites compete poorly with chaparral shrubs and
other tree species. Knobcone pine seedlings, however, can tolerate
nutrient-deficient soils which restrict the growth of most competitors
[14,29,41]. Knobcone pine does not vegetatively reproduce [19].
  • 15. Keeler-Wolf, Todd. 1986. An ecological survey of the proposed Stone Corral - Josephine Peridotite Research Natural Area (L. E. Horton - Darlingtonia Bog Research Nat. Area) on the Six Rivers National Forest, Del Norte County, California. Purchase order # 40-9AD6-5-907. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Intermountain Fire Sciences Laboratory, Missoula, MT. 69 p. [12307]
  • 3. Burcham, L. T. 1959. Planned burning as a management practice for California wild lands. In: Proceedings, 59th annual meeting of the Society of American Foresters: 180-185. [17037]
  • 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 19. Krugman, Stanley L.; Jenkinson, James L. 1974. Pinaceae--pine family. In: Schopmeyer, C. S., technical coordinator. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 598-637. [1380]
  • 29. McMillan, Calvin. 1956. The edaphic restriction of Cupressus and Pinus in the Coast Ranges of central California. Ecological Monographs. 26: 177-212. [11884]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]
  • 42. Vogl, Richard J. 1976. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 77-98. [4230]
  • 43. Vogl, Richard J. 1977. Fire: a destructive menace or a natural process?. In: Cairns, J., Jr.; Dickson, K. L.; Herricks, E. E., eds. Recovery and restoration of damaged ecosystems: Proceedings of the international symposium; 1975 March 23-25; Blacksburg, VA. Charlottesvile, VA: University Press of Virginia: 261-289. [10055]
  • 45. Warren, Richard; Fordham, Alfred J. 1978. The fire pines. Arnoldia. 38(1): 1-11. [18709]
  • 47. Wright, Robert D. 1968. Lower elevational limits of montane trees. II. Environment-keyed responses of three conifer species. Botanical Gazette. 129(3): 219-226. [19180]

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Growth Form (according to Raunkiær Life-form classification)

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More info for the term: phanerophyte

Phanerophyte

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Life Form

More info for the term: tree

Tree

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Life History and Behavior

Cyclicity

Phenology

More info on this topic.

Seeds germinate from early February through late March, depending on
elevation [47]. Pollination occurs from March until May [33].
  • 33. Munz, Philip A. 1973. A California flora and supplement. Berkeley, CA: University of California Press. 1905 p. [6155]
  • 47. Wright, Robert D. 1968. Lower elevational limits of montane trees. II. Environment-keyed responses of three conifer species. Botanical Gazette. 129(3): 219-226. [19180]

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Pinus attenuata

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Pinus attenuata

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 5
Specimens with Barcodes: 11
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2013

Assessor/s
Farjon, A.

Reviewer/s
Thomas, P. & Stritch, L.

Contributor/s

Justification

Pinus attenuata has an extensive extent of occurrence and is still numerous in certain parts of its range, especially in the northern counties of California. In certain areas close to urbanization fire prevention and suppression is likely to affect this species negatively in future, so a limited decline percentage is suspected for the future. However, this seems insufficient in relation to the global population size to place this species under threat or even to mark it as Near Threatened.

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National NatureServe Conservation Status

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Reasons: Southwestern Oregon to northern Baja California (Mexico), in scattered localities. In Mexico, it is quite rare in Mexico, where it is one of three pine species native to Baja California. Small populations near Ensenada should be protected and could serve as a source of seed for test plantings in the state of Baja California Norte. In the U.S. it occurs primarily in SW Oregon, with small populations in California.

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Population

Population
Numbers of mature trees in any given locality can fluctuate greatly with the incidence of fire, which tends to kill all trees. Regeneration from seeds normally follows this, and in the early stages seedlings and saplings can be numerous. However, this does not normally affect the global population, as these fires do not occur simultaneously everywhere, but are interspersed in space and time.

Population Trend
Stable
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Threats

Major Threats
Prevention of fire will eventually lead to the disappearance of this species from the forest community, which becomes then dominated by less fire-adapted tree species. Urbanization in many parts of its range is a potential threat that may lead to a decline in the near future.
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Management

Conservation Actions

Conservation Actions
This species occurs in several protected areas. Its long-term survival is closely dependent on fire regimes; management should attempt at maintaining the frequency and intensity of fires as close as possible to the natural situation. Knobcone Pine has apparently been planted in several localities in California (Griffin and Critchfield 1972 and several labels of herbarium specimens), some of which are outside its natural area of occupancy or even extent of occurrence. It is doubtful whether these can be interpreted as “benign introductions” and they are not considered as part of this assessment.
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Management considerations

More info for the terms: severity, tree

Knobcone pine populations are currently stable. The species is
apparently not subject to heavy insect or disease attack [44]. It may
become infected with dwarfmistletoe (Arceuthobium campylopodum), but the
literature is inconsistent on severity of infection. Mathiasen and
Hawksworth [23] believe that it is immune to such infestation. Kimmey
[16] reported it as "rarely infested" with western dwarf mistletoe (A.
campylopodum f. campylopodum), while Hempel [12] stated that it is
"often infected" with dwarfmistletoe. There are unconfirmed reports of
infestation in southwestern Oregon [10].

Feral pigs, which damage trees by tusking trunks with their canines,
commonly attack knobcone. Trees so tusked are often girdled for
distances of 3 to 4 inches (8-14 cm) up the trunk, resulting in death of
the tree. The motivation for this behavior in swine is unknown [4].
  • 4. de Nevers, Greg; Goatcher, Buddy. 1990. Feral pigs kill knobcone pines. Fremontia. 18(1): 22-23. [13656]
  • 10. Hawksworth, Frank G.; Johnson, David W. 1989. Biology and management of dwarf mistletoe in lodgepole pine in the Rocky Mountains. Gen. Tech. Rep. RM-169. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 38 p. [8651]
  • 12. Hempel, Kirsten. 1988. Dwarf mistletoe laying seige to pines. Forestry Research West. [Fort Collins, CO: U.S. Department of Agriculture, Forest Service]
  • 16. Kimmey, J. W. 1957. Dwarfmistletoes of California and their control. Tech. Pap. No. 19. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California Forest and Range Experiment Station. 12 p. [16464]
  • 23. Mathiasen, Robert L.; Hawksworth, Frank G. 1988. Dwarf mistletoes on western white pine and whitebark pine in northern California and southern California. Forest Science. 34(2): 429-440. [5034]
  • 44. Vogl, Richard J.; Armstrong, Wayne P.; White, Keith L.; Cole, Kenneth L. 1977. The closed-cone pines and cypress. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley and Sons: 295-358. [7219]

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Relevance to Humans and Ecosystems

Benefits

Value for rehabilitation of disturbed sites

Knobcone pine is planted for riparian and watershed rehabilitation in
areas with shallow, ultramafic, or sandy dry soils [8,13]. Survival and
growth rates are favorable. Plantation seedlings used for erosion
control in southern California attained heights of about 15 feet (4.6 m)
in 10 years. Trees are usually planted on-site from bareroot nursery
seedlings, although knobcone pine can be cloned if cuttings are taken
from trees less than 5 years of age. Seed collection and processing
techniques and details on seedling care are outlined in the literature
[13,19].
  • 8. Goldner, Bernard H. 1984. Riparian restoration efforts associated with structurally modified flood control channels. In: Warner, Richard E.; Hendrix, Kathleen M., eds. California riparian systems: Ecology, conservation, and productive management: Proceedings of the conference; 1981 September 17-19; Davis, CA. Berkeley, CA: University of California Press: 445-451. [5852]
  • 13. Horton, Jerome S. 1949. Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest]
  • 19. Krugman, Stanley L.; Jenkinson, James L. 1974. Pinaceae--pine family. In: Schopmeyer, C. S., technical coordinator. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 598-637. [1380]

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Importance to Livestock and Wildlife

Knobcone pine is unpalatable browse [13]. The heavily spiked, closed
cones deter most seed predators, although the western grey squirrel
consumes some seed. Jays eat seeds of opened cones [41,48].
  • 13. Horton, Jerome S. 1949. Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest]
  • 41. Vogl, Richard J. 1973. Ecology of knobcone pine in the Santa Ana Mountains, California. Ecological Monographs. 43: 125-143. [4815]
  • 48. Zedler, Paul H. 1986. Closed-cone conifers of the chaparral. Fremontia. 14(3): 14-17. [18648]

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Wood Products Value

There is no commercial market for knobcone pine wood [11].
  • 11. Hayes, G. L. 1959. Forest and forest-land problems of southwestern Oregon. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 54 p. [8595]

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Wikipedia

Knobcone pine

The knobcone pine, Pinus attenuata, (also called Pinus tuberculata[2]) is a tree that grows in mild climates on poor soils. It ranges from the mountains of southern Oregon to Baja California with the greatest concentration in northern California and the Oregon-California border.[3]

Description[edit]

The knobcone pine (Pinus attenuata) crown is usually conical with a straight trunk. It reaches heights of 8–24 metres (26–79 ft).[4] However, it can be a shrub on especially poor sites. It prefers dry rocky mountain soils. The bark is smooth, flaky and gray-brown when young, becoming dark gray-red-brown and shallowly furrowed into flat scaly ridges. The twigs are red-brown and often resinous.

The leaves are in fascicles of three,[5] needle-like, yellow-green, twisted, and 9–15 cm (about 3.5–6 in) long. The cones are 8–16 cm long and clustered in whorls of three to six on the branches. The scales end in a short stout prickle. The cones remain closed for many years until a fire opens them and allows reseeding. As a result, the cones may even become embedded in the trunk as the tree grows.

Ecology[edit]

The knobcone pine (Pinus attenuata) forms nearly pure stands, however it may hybridize with bishop pine (Pinus muricata), and Monterey pine (Pinus radiata) on the coast.

In the western foothills of the Sierra Nevada, knobcone pine is often a co-dominant with blue oak (Quercus douglasii).[6]

References[edit]

  1. ^ Conifer Specialist Group, 1998
  2. ^ Chase, J. Smeaton (1911). Cone-bearing Trees of the California Mountains. Chicago: A. C. McClurg & Co. p. 99. LCCN 11004975. OCLC 3477527.  LCC QK495.C75 C4, with illustrations by Carl Eytel - Kurut, Gary F. (2009), "Carl Eytel: Southern California Desert Artist", California State Library Foundation, Bulletin No. 95, pp. 17-20 retrieved Nov. 13, 2011
  3. ^ Moore, Gerry; Kershner, Bruce; Craig Tufts; Daniel Mathews; Gil Nelson; Spellenberg, Richard; Thieret, John W.; Terry Purinton; Block, Andrew (2008). National Wildlife Federation Field Guide to Trees of North America. New York: Sterling. p. 85. ISBN 1-4027-3875-7. 
  4. ^ Gymnosperm Database, 2008
  5. ^ eNature Field Guides, 2007
  6. ^ C. Michael Hogan, 2008

Further reading[edit]

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Notes

Comments

Pinus attenuata , mostly a chaparral species, bears cones at an early age. Its seed crops are heavy, and a hot fire permits the seeds to be released. It forms hybrids with P . muricata and P . radiata .
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Names and Taxonomy

Taxonomy

The currently accepted scientific name of knobcone pine is Pinus
attenuata Lemm. [21,33,36]. There are no subspecies or varieties. The
distributions of knobcone and Monterey (P. radiata) pines overlap in
Santa Cruz County, where they produce the hybrid P. X attenuradiata
Stockw. & Right [21,33,35].
  • 21. Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. 375 p. [2952]
  • 33. Munz, Philip A. 1973. A California flora and supplement. Berkeley, CA: University of California Press. 1905 p. [6155]
  • 36. Preston, Richard J., Jr. 1948. North American trees. Ames, IA: The Iowa State College Press. 371 p. [1913]
  • 35. Pharis, Richard P.; Wample, Robert L.; Kamienska, Aniela. 1975. Growth, development, and sexual differentiation in Pinus, with emphasis on the role of the plant hormone, gibberellin. In: Baumgartner, David M., ed. Management of lodgepole pine ecosystems: Symposium proceedings; 1973 October 9-11; Pullman, WA. Vol. 1. Pullman, WA: Washington State University, Cooperative Extension Service: 106-134. [7823]

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Common Names

knobcone pine

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