Desert Communities

1
Coronado National Forest
D R A F T Vegetation Desired Condition
Desert Communities In the desert communities, the
predominant species are native. There is sparse
to dense vegetation cover that includes succulent
species, desert grasses, desert scrub, and some
herbaceous cover. Some species occurring in
desert communities include catclaw acacia,
triangleleaf bursage, white bursage, mesquite,
desert ironwood, saltbush, cresosote, iodine
bush, splitleaf brickellia, desert broom, desert
willow, cheesebush, barrel cactus, hedgehog
cacti, cholla and prickly pear, saguaro, salt
grass, rice grasses, and dropseed grasses. Fires
are rare. Semi-desert Grasslands The Coronado
NF semi-desert grasslands are a botanically
diverse plant community fully a quarter of the
plant species of the Coronado NF occur in the
semi-desert grasslands. Species composition and
dominance varies across the broad range of soils
and topography, but are dominated by native warm
season and cool season perennial grasses
including one or some of the following little
bluestem, sand dropseed, blue grama, sideoats
grama, hairy grama, New Mexico feathergrass,
needle and thread grass, Indian ricegrass,
threeawn spp., fescue spp., curly mesquite,
tobossa grass, bristly wolfstail and plains
lovegrass. Forbs and half-shrubs are interspersed
between grasses and vary greatly with rainfall
and disturbance. These include Brickelbush,
blanketflowers, goldfields, Zinnias, morning
glories, globemallows, four o'clocks, evening
primroses, penstemons, verbenas and many others.
Various shrubs also occupy these grasslands in
varying abundances, but do not co-dominate the
community and are sparse in many area (less than
10 percent cover). Shrub species may include, but
are not limited to mesquite, catclaw mimosa,
Apache plume, saltbush, sotol, beargrass, Yucca,
Palmers Agaves, winterfat, one-seeded juniper,
cholla, prickly pear and skunkbush sumac. Fire
plays a key role in maintaining the grasslands,
with large, low intensity fires usually occurring
in the early summer, every 2.5 to 10 years. These
fires reduce shrub cover while having little
negative effect on grasses. Interior Chaparral
The interior chaparral varies from widely
scattered pockets within grasslands and woodlands
to more extensive areas on steep mountain slopes.
Interior chaparral consists of mixed shrub
associations including, but not limited to the
following species Manzanita, desert ceanothus,
mountain mahogany, little-leaved mountain
mahogany, antelope bushes, silktassles, Stansbury
cliffrose, Sonoran scrub oak, Toumey oak, Emory
oak and sumacs. The canopy is nearly closed in
about 90 percent of the community. Fire regimes
are a natural dynamic that provide landscape
diversity, wildlife habitat and soil stability to
maintain these communities in a variety of
densities and age classes. (Continued on other
side)
October 2008
2
Madrean Encinal Woodland In the Madrean encinal w
oodland, the predominant tree species are
evergreen oaks, and most of these are tree forms,
not shrubs. Dominant species include Madrean
evergreen oaks such as Arizona white oak, and
Emory oak, with lesser amounts of Mexican blue
oak and Toumey oak. Madrean pines, border piñon,
Arizona cypress, alligator and single-seed
junipers, and interior chaparral species may be
present, but do not co-dominate. The ground cover
is dominated by grasses such as threeawns, blue
grama, sideoats grama, Rothrock grama, Arizona
cottontop, plains lovegrass, curly-mesquite,
green sprangletop, muhly grasses, or Texas
bluestem. The native, perennial, generally warm
season, bunchgrass dominance in the understory
creates a wide overlap with the semi-desert
grasslands. Frequent but highly variable, low
intensity, early summer fires maintain overstory
canopy at less than 20 percent in about 60
percent of the community. Madrean Pine-Oak Woo
dland In the Madrean pine-oak woodland, the predo
minant tree species are evergreen oaks and
Madrean pines including Arizona white oak, Emory
oak, silverleaf oak, Apache pine, and Chihuahua
pine. Other commonly occurring trees include
alligator juniper, Arizona madrone, Arizona
cypress and border piñon. A shrub layer is
present and often contains species such as
beargrass, littleleaf and evergreen sumac,
silktassel, birchleaf buckthorn, and Ceanothus
species. Muhly bunchgrass are common, including
long tongue muhly and bullgrass. The Madrean
pines dominate the highest level of the overstory
and perennial warm season bunchgrasses provide
the majority of ground cover. Canopy may be open
or closed. The midstory oaks are mostly tree
form and do not dominate the landscape. Frequent,
low intensity fires maintain this understory over
90 percent of the community. However, infrequent
fire free intervals occur, up to thirty years
long, allowing pine regeneration and
establishment. Most fires are generally low
intensity surface fires that remove surface fuels
and maintain spacing in the overstory, but do not
damage soils. Fires are easily controlled when
necessary for safety or resource considerations.
Ponderosa Pine The dominant species in this sys
tem is ponderosa pine and occasionally Arizona
pine. Other trees, such as Gambel oak, silverleaf
oak, netleaf oak, Douglas-fir, pinyon pine, and
juniper may be found but do not dominate the
forest. Oaks occur primarily in tree form, not
shrub form. There is a shrubby understory mixed
with grasses and forbs, sometimes forming a pine
savannah with more extensive grasslands
interspersed between widely spaced clumps or
individual trees. Native bunchgrasses and a thin
pine needle litter layer occupy the forest floor
nearly completely. This system is maintained by
frequent, low intensity surface fires resulting
in open forests with fire resilient mature trees
providing about 20 percent canopy, rarely
reaching over 30 percent. Mixed Conifer/Aspen
Forest The dominant trees are Douglas-fir, Ponde
rosa pine, southwestern white pine, and lesser
amounts of white fir and only occasional
sub-alpine conifers such as Englemann spruce.
Typically these trees occur in groups of patches.
Some of the area is open, perhaps from recent
burns, insect attack, or active management. Small
patches of aspen pepper the landscape along with
and young groups of Douglas-fir, ponderosa pine,
and southwestern white pine. Fire plays a
primary role in creating a highly diverse
landscape of varying size classes and tree
species present. Frequent low intensity surface
fires are still the norm but occasionally patchy
crown fires occur creating opportunities for
aspen clones to resprout and persist for a time.
Spruce-fir More than 40 percent of the spruce-f
ir type is occupied by mature trees with a closed
canopy and a sparse understory with few grasses,
forbs or shrubs. The dominant trees are
Englemann spruce, and corkbark fir. The
remaining area has robust regeneration of younger
subalpine conifers, and scattered patches of
aspen, Douglas-fir and southwestern white pine.
Recent evidence of fire or insect attack is rare.