BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Pinus engelmannii | Apache Pine 



GENERAL BOTANICAL CHARACTERISTICS : 
Apache pine is a native, monoecious tree.  Mature individuals are 50 to
82 feet (15-25 m) tall and have trunk diameters from 14 to 32 inches
(35-80 cm) [13,25,30,45].  The bark on mature trees is about 1.5 inches
(3.8 cm) thick [25].  The crown is open and round with few large
branches [33,45].  Evergreen needles are in bundles of three or
occasionally four or five and are 8 to 15 inches (20-38 cm) long
[25,32,42,45].  Cones are 4 to 7 inches (10-18 cm) long and are borne in
pairs or groups of four [25,42,45].  Seeds are just over 0.25 inch (0.6
cm) long with large wings up to 1 inch (2.5 cm) long [25,61].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Apache pine reproduces by seed; no information on vegetative
reproduction was found in the literature.  Apache pine populations in
Chihuahua, Mexico, produce synchronous seed crops at irregular intervals
[52].  Apache pine begins to bear cones when 28 to 30 years old [30].
Although the intervals between large seed crops are 2 to 4 years, some
seeds are produced every year in parts of its range [25,30].  Cones
mature in 2 years [25].  The seeds weigh only 0.002 ounces (0.05 g) and
are wind dispersed [25,57].  Animals consume some seed [25], but it was
not found in the literature whether animals contribute to effective
dispersal and establishment of Apache pine.

Information about cone and seed collection and seed germination
conditions are discussed in the literature [30].  Optimal germination
occurs on broken and washed mineral soil [25].

Apache pine seedlings tolerate significantly (P<0.05) lower light than
found in random microsites [4].  Seedlings and saplings have long
needles, about 6 inches in length (15 cm) [33], which may increase net
photosynthesis under low light conditions.

Apache pine seedlings produce a relatively deep taproot and little
top-growth during their first few years [46].  Near the lower
elevational limit of this species, Apache pine seedlings occur in
relatively moist microsites.  Just below the lowest elevational limit,
Apache pine seedlings die from water stress [4].  Juveniles and saplings
that have trunk diameters less than 2 inches (5 cm) at the base and are
less than 3.2 feet (1 m) tall have less effective root systems for
withstanding drought than mature trees [5,62].


SITE CHARACTERISTICS : 
Apache pine grows in climates that range from semiarid with bimodal
precipitation to temperate-subhumid with most precipitation falling in
summer [5,60].

Apache pine grows on dry to moderately moist canyon slopes, ridges,
mesas, lower slopes, valleys, and streamside terraces [6,15,39,43,
45,54].  Apache pine ranges from 5,000 to 9,100 feet (1,524-2,750 m) in
elevation [5,16,18,37,43,45,60].

Apache pine occurs on soils of varying depths and textures.  Soils can
be 4 to 6 inches (10-15 cm) deep with textures ranging from sandy to
clayey sand with gravel [5,25,60].  Parent material can be igneous,
rhyolite, basalt, or schist [7,60].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Apache pine is shade tolerant during establishment [4,25].  It becomes
shade intolerant after about 6 years [25].

The successional status of Apache pine depends on location and
associated species.  It may be seral to or climax with any of the
conifer species in mixed pine forests [15].  Apache pine is a climax
species in the Madrean pine-oak woodlands and forests [6].



SEASONAL DEVELOPMENT : 
Needles remain on Apache pine for 2 years.  Seed production requires 2
years [25].  Pollination occurs mainly during May [30,50].  Cones mature
from November to December of the second year [30,45].  Seeds disperse
from November to February [30,50].

Related categories for Species: Pinus engelmannii | Apache Pine