BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Abies bracteata | Bristlecone Fir 



GENERAL BOTANICAL CHARACTERISTICS : 
Bristlecone fir is a native, evergreen, medium-sized tree.  Mature
height ranges from 30 to 100 feet (9-30 m) [21].  Average heights at 100
years of age were reported as 40, 70, and 90 feet (12, 21, and 27 m) for
summit, transition, and ravine sites, respectively [27].  Bristlecone
fir is easily distinguished by a dense branching pattern that begins
near the ground and terminates in a tall, narrow point [6,21].  Branches
tend to decline or droop [21].  Mature ovulate cones are 3 to 4 inches
(7.6-10.1 cm) long and have long, needle-like points (0.78 to 1.57
inches [2-4 cm]) on the ends of the scale bracts, giving the cone a
frilled or bristled appearance [1,6].  The needles are flat, stiff, and
1 to 2 inches (2.5-5 cm) long [21,22].  The bark of mature stems is
smooth to slightly fissured and broken into appressed scales [21].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Large crops of bristlecone fir cones are produced every 3 to 5 years
[6,33].  Seeds are parasitized by seed chalcids (wasps).  Up to 100
percent of the total bristlecone fir seed crop is parasitized some
years, but occasional large cone crops exceed the parasitization
capacity of the chalcids.  A large cone crop in 1971 resulted in viable
seed production in 1973 [27].  The winged seeds are chiefly dispersed by
wind [33].  In a greenhouse study, 80 percent of viable bristlecone fir
seeds germinated under a 5 degrees Fahrenheit (3 deg C) diurnal
temperature range.  Above 73.4 degrees Fahrenheit (23 deg C), however,
germination rates decline.  After-ripening, cool, and/or moist
treatments are not required for germination [27].

Bristlecone fir seedlings are sensitive to drought.  Repeated
desiccation and high surface temperatures were probably reponsible for
the 1974 absence of bristlecone fir seed germination on chaparral,
grassland, and summit sites despite the good cone crop of the previous
fall.  During that time, drought resulted in mortality of first year
seedlings on all sites except very near the coast and on new (created
after 1970) burns [27].


SITE CHARACTERISTICS : 
Bristlecone fir occurs in windswept canyons on steep, rocky, or gravelly
sites at elevations ranging from 690 to 5,164 feet (210-1,571 m).  The
average slope of bristlecone fir sites ranges from 35 to 40 degrees;
adjacent forests have an average slope of 25 degrees [27].  Average
annual precipitation is between 35 and 40 inches (998-1,000 mm) at
around 4,000 feet (1,216 m) in the Santa Lucia Mountains [25,27].  Less
than 2 percent of annual precipitation falls between June 1 and
September 30 [27].  The confinement of bristlecone fir to the Santa
Lucia Mountains and its absence from the Sierra Nevada are consistent
with the species' apparent requirement for a mild climate and low summer
evaporation rates [1].

Bristlecone fir occurs on soils derived from ultrabasic rocks but is not
limited to them [24].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Bristlecone fir height growth is correlated with the amount of light
striking the forest floor.  Summer light levels below 30 langleys per
day are limiting to sapling growth [27].  Bristlecone fir groves are
probably climax on steep slopes.  Bristlecone fir is a member of canyon
live oak communities, which are climax woodlands on steep slopes in the
Santa Lucia Mountains.  Fire in canyon live oak woodlands can cause
internal shifts in species composition, but the area occupied by the
plant community usually does not change.  Repeated burning may convert
open canyon live oak stands to chaparral, but the community will again
succeed to canyon live oak with long fire-free intervals [7].


SEASONAL DEVELOPMENT : 
Staminate cones shed pollen in May.  Ovulate cones mature in late
August of the same year, shedding bracts and seeds in September [6].

Related categories for Species: Abies bracteata | Bristlecone Fir