BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Pinus jeffreyi | Jeffrey Pine 



GENERAL BOTANICAL CHARACTERISTICS : 
Jeffrey pine may live 400 to 500 years and can attain immense size.  The
species typically grows 4 to 6 feet (1.2-2.8 m) in diameter and 170 to
200 feet (52-61 m) in height.  The largest Jeffrey pine found in the
western Sierra Nevada measures 7.5 feet (2.28 m) in diameter and 175
feet (53 m) in height [3,17].  The bark is deeply furrowed with hard
scales and lacks resin pits.  Needles are in bundles of three and are
7.5 to 11 inches (12-28 cm) long, persisting 5 to 8 years.  Female cones
are subterminal, long-oval, and are 6 to 10 inches (15-25 cm) long [30].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Jeffrey pine regenerates sexually.  It does not reproduce naturally by
vegetative methods.

Flowering and Fruiting:  Jeffrey pine is monoecious.  Following
pollination, the conelets develop slowly, achieving less than one-fifth
their mature size the first growing season.  Fertilization occurs about
13 months after pollination, and cones reach full size during the second
summer.  Mature cones normally shed their seeds in September or October
[11,21,24].

Seed production and dissemination:  Trees as young as 8 years have borne
cone crops, although typically cone-bearing Jeffrey pines are 60 to 180
feet (18-55 m) tall and produce large seed crops every 2 to 8 years.
Seeds are typically strewn 7.2 ft/s (2.2 m/s) from the source when
carried by winds of 5 mi/h (8 km/h).  Heavy winds may disperse seeds up
to 2,460 feet (750 m) from a tree height of 164 feet (50 m).  Wildlife,
such as the Clark's nutcracker, also aids in seed dissemination.  Vander
Wall [42] found dissemination patterns of Jeffrey pine linked
extensively to animal hoarding of seeds in shallow surface caches.
Small mammals such as the golden-mantled ground squirrel and western
gray squirrel, in addition to mice and voles, harvest and store the
seeds [14,21,24,39].

Growth and yield:  In comparison, Jeffrey pine grows less rapidly than
ponderosa pine during the sapling stage but more rapidly in the pole
stage.  Jeffrey pine generally grows to the same age and size as
ponderosa pine.  Jeffrey pine lateral roots are strong and extensive.
On favorable sites, live roots up to 2 inches (5 cm) in diameter were
found approximately 100 feet (30 m) away from the source [17,21].
Generally, Jeffrey pine trees grown from seed collected east of the
Sierra Nevada are slower growing, more drought resistant, and less
susceptible to cold damage than Jeffrey pine trees grown from seed
collected elsewhere.  Also, trees from high elevations tend to be slower
growing than those from lower elevations [24].

Seedling development.  Seeds collected from various areas require
different periods of moist, cold stratification for rapid and complete
germination.  Most stored seeds germinate best after 60 days of
stratification.  Nursery stock seeds are sown in April and achieve a
plantable size in one growing season.  Planting begins at the onset of
spring conditions.  With adequate spring rain, field survival ranges
from 90 to 99 percent [20,21,24].


SITE CHARACTERISTICS : 
Jeffrey pine occupies many sites from the edges of moist high montane
meadows to arid slopes bordering deserts.  It generally occurs on the
drier or higher elevation sites on soils derived from pumic or granite.
Its northwest population is strongly correlated with edaphic factors,
while the northeast, central, and southern populations strongly reflect
climatic and elevational factors [21,27,33].

Climate:  Most populations east of the Sierra-Cascade crest are exposed
to January mean temperatures between 8 and 23 degrees F (-13 to -5 deg
C), while those in the west and south are between 19 and 36 degrees F
(-7 to 2 deg C).  Summer temperatures in July can be from 34 degrees F
(1 deg C) to 47 degrees F (8 deg C) throughout its distribution.
Precipitation falls mostly as snow.  Average snowfall typically ranges
from 12 inches (30 cm) or less at the lowest elevations in the Klamath
Mountains to well over 204 inches (520 cm) at high elevations in the
Sierra Nevada [21].

Soils and topography:  Twenty percent of the Jeffrey pine distribution
lies on ultramafic soils.  On the western slope of the northern Sierra
Nevada, and in the North Coast Range and Klamath Mountains, Jeffrey pine
often dominates and is almost entirely restricted to soils derived from
ultramafic rocks, peridotites, or serpentines.  Typical soils occupied
by Jeffrey pine are fine, fine-loamy, and clayey-textured skeletal
surface soils.  These soils are highly infertile and mostly shallow.
Jeffrey pine typically grows on granitic soils in the Sierra Nevada
[21].

Elevation:  In the northern Sierra Nevada, Jeffrey pine commonly occurs
at 5,000 to 6,000 feet (1,520-1,830 m), rising to 7,000 to 9,000 feet
(2,130-2,740 m) to the south [3].  In the Sierra San Pedro Martin, it
ranges from 6,000 to 10,000 feet (1,830-3,050 m) [33].  At high
elevations Jeffrey pine becomes deformed by strong winds [27].


SUCCESSIONAL STATUS : 
Jeffrey pine is common in the Sierra Nevada, but it is confined to
scattered outcrops of peridotite and serpentine in the northern most
extent of its range in the Siskiyou Mountains, Oregon.  Jeffery pine is
climax on many of these sites but gradually loses its competitve ability
as moisture conditions in the soil and atmosphere become favorable for
other species [2].  Jeffrey pine is a strong invader species in Lassen
Volcanic National Park, California.  The elimination of competing
vegetation by volcanic activity facilitates the establishment of pine
seedlings [18,37].  Factors relating to poor seed dispersal seem to be
the major limiting factor in the natural succession of Jeffrey pine
[18].

Jeffrey pine overlaps extensively with ponderosa pine and sugar pine
(Pinus lambertiana) on the western slopes of the Sierra Nevada,
California.  In mixed stands on favorable growing sites, Jeffrey pine is
generally seral to more tolerant conifers such as Douglas-fir
(Pseudotsuga menziesii), white fir, incense cedar, and red fir (Abies
magnifica) [46].  In the Sierra Nevada, California, young Jeffrey pine
was found to have a high mortality rate due to an outbreak of Jeffrey
pine beetles (Dendroctonus jeffreyi).  This susceptibility allows for
successional replacement, while also creating important habitat for
wildlife [35].



SEASONAL DEVELOPMENT : 
Jeffrey pine seasonal development closely follows that of Pacific
ponderosa pine (Pinus ponderosa var. ponderosa).  Jeffrey pine flowers
from June to July; cone ripening and seed dipersal occur from September
to October.  See Pacific ponderosa pine write-up for further information
[21].

Related categories for Species: Pinus jeffreyi | Jeffrey Pine