occurs in the Chiricahua, Huachuca, Dragoon, and Santa Rita mountains of
Arizona and in one area of extreme southwestern New Mexico [13,18,34,
42,61]. The main part of its range is in Mexico. Apache pine occurs
commonly in the Sierra Madre Occidental, extending southward from the
United States border to Zacatecas [14,28,44,45].
Regional Distribution in the Western United States
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):
7 Lower Basin and Range
Occurrence in North America
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 . 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].
Arizona Mountains Forests Habitat
This taxon is found in the Arizona Mountain Forests, which extend from the Kaibab Plateau in northern Arizona to south of the Mogollon Plateau into portions of southwestern Mexico and eastern Arizona, USA. The species richness in this ecoregion is moderate, with vertebrate taxa numbering 375 species. The topography consists chiefly of steep foothills and mountains, but includes some deeply dissected high plateaus. Soil types have not been well defined; however, most soils are entisols, with alfisols and inceptisols in upland areas. Stony terrain and rock outcrops occupy large areas on the mountains and foothills.
The Transition Zone in this region (1980 to 2440 m in elevation) comprises a strong Mexican fasciation, including Chihuahua Pine (Pinus leiophylla) and Apache Pine (P. engelmannii) and unique varieties of Ponderosa Pine (P. ponderosa var. arizonica). Such forests are open and park-like and contain many bird species from Mexico seldom seen in the U.S.. The Canadian Zone (above 2000 m) includes mostly Rocky Mountain species of mixed-conifer communities such as Douglas-fir (Pseudotsuga menziesii), Engelmann Spruce (Picea engelmanni), Subalpine Fir (Abies lasiocarpa), and Corkbark Fir (A. lasiocarpa var. arizonica). Dwarf Juniper (Juniperus communis) is an understory shrubby closely associated with spruce/fir forests. Exposed sites include Chihuahua White Pine (Pinus strobiformis), while disturbed north-facing sites consists primarily of Lodgepole Pine (Pinus contorta) or Quaking Aspen (Populus tremuloides).
There are a variety of mammalian species found in this ecoregion, including the endemic Arizona Gray Squirrel (Sciurus arizonensis), an herbivore who feeds on a wide spectrum of berries, bark and other vegetable material. Non-endemic mammals occurring in the ecoregion include: the Banner-tailed Kangaroo Rat (Dipodomys spectabilis NT); Desert Pocket Gopher (Geomys arenarius NT). In addition, there is great potential for restoring Mexican Wolf (Canis lupus) and Grizzly Bear (Ursus arctos horribilis) populations in the area because of its remoteness and juxtaposition to other ecoregions where these species were formerly prevalent.
There are few amphibians found in the Arizona mountain forests. Anuran species occurring here are: Red-spotted Toad (Anaxyrus punctatus); Southwestern Toad (Anaxyrus microscaphus); New Mexico Spadefoot Toad (Spea multiplicata); Woodhouse's Toad (Anaxyrus woodhousii); Northern Leopard Frog (Lithobates pipiens); Chiricahua Leopard Frog (Lithobates chiricahuensis VU); Madrean Treefrog (Hyla eximia), a montane anuran found at the northern limit of its range in this ecoregion; Boreal Chorus Frog (Anaxyrus woodhousii); Western Chorus Frog (Pseudacris triseriata); and Canyon Treefrog (Hyla arenicolor). The Jemez Mountains Salamander (Plethodon neomexicanus NT) is an ecoregion endemic, found only in the Jemez Mountains of Los Alamos and Sandoval counties, New Mexico. Another salamander occurring in the ecoregion is the Tiger Salamander (Ambystoma tigrinum).
A number of reptilian taxa occur in the Arizona mountains forests, including: Gila Monster (Heloderma suspectum NT), often associated with cacti or desert scrub type vegetation; Narrow-headed Garter Snake (Thamnophis rufipunctatus), a near-endemic found chiefly in the Mogollon Rim area; Sonoran Mud Turtle (Kinosternon sonoriense NT).
Key Plant Community Associations
Apache pine primarily occurs in Madrean pine-oak and oak-pine forests
and woodlands. Codominant and subdominant species that occur with
Apache pine in these communities are Chihuahua pine (Pinus leiophylla
var. chihuahuana), Mexican pinyon (P. cembroides), and alligator
juniper (Juniperus deppeana); the understories are predominatly oak
(Quercus spp.) [1,7,11,21,22,35]. The communities may extend upward
into the mixed pine forests .
Apache pine forms open stands and is widely scattered in mixed pine
forests with Arizona pine, Chihuahua pine, and southwestern white pine
(P. strobiformis) [2,15,29].
Apache pine is the principal species in the Apache pine series
Scattered Apache pine occur in riparian habitats. Along streamsides,
Apache pine is a minor species in some stands of Chihuahua pine/pinyon
ricegrass (Piptochaetium fimbriatum) habitat types and is codominant in
Arizona cypress (Cupressus arizonica) types [15,39,41,48]. It is a
minor species in the Arizona sycamore (Platanus wrightii) series and
community types [39,56].
Apache pine is listed as a dominant or indicator species in the
(1) Classification of the forest vegetation on the National Forests of
Arizona and New Mexico 
(2) Forest and woodland habitat types (plant associations) of Arizona
south of the Mogollon Rim and southwestern New Mexico 
(3) A digitized computer-compatible classification for natural and
potential vegetation in the Southwest with particular reference to
(4) A series vegetation classification for Region 3 
(5) A forest habitat type classification of southern Arizona and its
relationship to forests of the Sierra Madre Occidental of Mexico .
Species associated with Apache pine but not previously mentioned in
Occurrence and Distribution include Arizona madrone (Arbutus arizonica),
Apache plume (Fallugia paradoxa), western white honeysuckle (Lonicera
albiflora), and slimflower scurfpea (Psoralea tenuiflora) [16,48].
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):
FRES21 Ponderosa pine
FRES28 Western hardwoods
FRES35 Pinyon - juniper
precipitation to temperate-subhumid with most precipitation falling in
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
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].
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
235 Cottonwood - willow
237 Interior ponderosa pine
239 Pinyon - juniper
240 Arizona cypress
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K019 Arizona pine forest
K023 Juniper - pinyon woodland
K031 Oak - juniper woodlands
Habitat & Distribution
Fire Management Considerations
Increased grazing coupled with fire suppression has resulted in crowded,
stunted Apache pine with high amounts of litter and dead fuel in the
oak-pine communities . This increases the fire hazard in these
Fire is the primary control for southwestern dwarf mistletoe infection.
Prescribed understory burning has been used in interior ponderosa pine
forests to control this pathogen . Since Apache pine and interior
ponderosa pine respond similarly to southwestern dwarf mistletoe
infection , fire may be useful for controlling mistletoe in Apache pine.
Plant Response to Fire
Since regeneration of Apache pine is exclusively through seed, rates of
regeneration are probably dependent on survival of mature trees within
the burn and the proximity of seed trees. Seeds will germinate in
mineral soil exposed by fire as long as adequate moisture is present.
Immediate Effect of Fire
Fire effects on Apache pine are probably influenced most by tree size
and fire intensity. Apache pine seedlings and saplings are probably
killed by fire. With thicker bark and deeper roots, mature trees are
fire resistant . Once shed, the small seeds with large wings are
probably killed by fire unless they are covered with an insulating layer
Tree without adventitious-bud root crown
Crown residual colonizer (on-site, initial community)
Secondary colonizer - off-site seed
Mature Apache pine endure most fires and become dominant when fire
susceptible species are eliminated [7,37].
Apache pine grows in oak-pine woodlands; these are probably
fire-tolerant, fire-maintained communities, although the fire regime is
not well understood for these associations . Apache pine occurs in
the Madrean oak-pine forest and adjacent conifer gallery forest in
Rhyolite Canyon in the Chiricahua National Monument, Arizona.
Historically, surface fires occurred episodically every 1 to 38 years
. Based on the fire-scars of Apache pine, the mean fire interval
from 1655 to 1924 was 12.5 years in the lower canyon area . Fire
intervals increased with livestock grazing and the subsequent reduction
in surface fuels .
Fire is characteristic of interior ponderosa pine forests. Fires from
these communities may extend downward into mixed pine or oak-pine
forests in which Apache pine occurs. In the Rincon Mountains close to
the northern latitudinal limits of Apache pine, the estimated mean fire
intervals from 1757 to 1983 for Arizona pine communities ranged from 1
to 13 years .
More info for the term: climax
Facultative Seral Species
Apache pine is shade tolerant during establishment [4,25]. It becomes
shade intolerant after about 6 years .
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 . Apache pine is a climax
species in the Madrean pine-oak woodlands and forests .
reproduction was found in the literature. Apache pine populations in
Chihuahua, Mexico, produce synchronous seed crops at irregular intervals
. Apache pine begins to bear cones when 28 to 30 years old .
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 . The seeds weigh only 0.002 ounces (0.05 g) and
are wind dispersed [25,57]. Animals consume some seed , 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 . Optimal germination
occurs on broken and washed mineral soil .
Apache pine seedlings tolerate significantly (P less than 0.05) lower light than
found in random microsites . Seedlings and saplings have long
needles, about 6 inches in length (15 cm) , 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 . 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 . 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].
Growth Form (according to Raunkiær Life-form classification)
Life History and Behavior
Needles remain on Apache pine for 2 years. Seed production requires 2
years . 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].
Molecular Biology and Genetics
Barcode data: Pinus engelmannii
Statistics of barcoding coverage: Pinus engelmannii
Public Records: 8
Specimens with Barcodes: 16
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Apache pine was evaluated for suitability as a timber tree at the Wind
River Arboretum in Wyoming. Most transplanted trees died; three trees
survived for 55 years. At that time, they had poor vigor, needle
disease, snow and ice damage, and no reproduction .
Apache pine was included in a breeding program that studied pollen
production at the Eddy Arboretum in California. Apache pine produced
pollen from April through June over a 6-year period .
Equations to estimate understory production have been developed for the
oak-pine forests in which Apache pine occurs .
In the oak-pine forests where Apache pine is an overstory tree, the
removal of large nest trees for fuelwood can reduce habitat suitability
for the Mexican spotted owl .
Apache pine is susceptible to southwestern dwarf mistletoe (Arceuthobium
vaginatum ssp. cryptopodum). Control methods are discussed in the
Relevance to Humans and Ecosystems
Importance to Livestock and Wildlife
other animals consume its seeds [25,32,59]. The intensity of seed
predation was not described in the literature. However, Apache pine has
synchronous cone crops at irregular intervals ; such masting may
have evolved in response to heavy seed predation.
Mexican spotted owls are yearlong residents of the Madrean oak-pine
forests to which Apache pine belongs .
Wood Products Value
The limited distribution of Apache pine restricts its commercial
importance [13,18,33]. The wood of Apache pine is hard and heavy
[25,61]. It is sometimes harvested with associated pines for lumber and
construction timbers. Apache pine is used locally for fuel .
Pinus engelmannii, commonly known as the Apache pine, is a tree of Northern Mexico, in the Sierra Madre Occidental with its range extending a short distance into the United States in southwestern New Mexico and southeastern Arizona. This pine is a medium-sized species with a height of 20–30 m and a trunk diameter of 35–80 cm.
The branches are sparse and very stout, giving the tree a distinct appearance. The needles, among the longest of any pine, are in bundles of three (occasionally five), 20–40 cm long, stout, and spreading to slightly drooping. The cones are 8–16 cm long, green or purple when growing, maturing glossy brown, moderately oblique with stoutly spined scales on the outer side (facing away from the branch). The Apache pine sometimes shows a grass stage like the related Michoacan pine (P. devoniana) and also longleaf pine (P. palustris).
The English name refers to the species' occurrence in the lands of the Apache Native Americans, while the scientific name commemorates the pioneering American botanist George Engelmann who discovered the species in 1848. Engelmann first named the species Pinus macrophylla, but this name had already been used for another pine, so it had to be renamed; this was done by the French botanist Carrière, who chose to honour Engelmann.
Apache pine was sometimes treated as a variety of ponderosa pine in the past (as P. ponderosa var. mayriana), but it is now universally regarded as a distinct species.
Names and Taxonomy
Arizona longleaf pine
engelmannii Carr. It is a member of the pine family (Pinaceae)
[14,30,61,62]. In addition to the typical variety, there is one
recognized variety in Mexico, P. e. var. blancoi Mart. [7,45,62].
Where their ranges overlap, interspecific hybrids occur between Apache
pine, interior ponderosa pine (P. ponderosa var. scopulorum), and Arizona
pine (P. p. var. arizonica) [12,43,44,49].
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