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Multiple Use Management Based on
Diversity of Capabilities and Values Within
Pinyon-Juniper Woodlands
Sherel Goodrich
Abstract-Different wildlife species respond differently to different seral stages of pinyon-juniper ecosystems. People also have
widely different preferences and uses associated with different
stages of succession. Bighorn sheep prefer early seral communities,
while forage values for elk and mule deer are much higher in early
to mid seral stages, and mature stands provide hiding and thermal
cover. Trees used as Christmas trees are more common from young,
open stands. Some birds require older stands for seed. Pinyon seed
crops are important commercially and for personal use. Some
wildlife species are cavity nesters and require large trees in mature
stands. Firewood and cedar posts come from mature stands. Watershed values can also vary with seral stage. Visual and intrinsic
preferences vary greatly among individuals. To integrate such
diverse values into management for multiple uses, managers use
tools that include an inventory of ecological units, and studies and
recorded observations for each ecological unit, to understand capabilities and values of separate units within landscapes. Application
of such an inventory to multiple use management is explored.
Under the Multiple use Sustained Yield Act of 1960 and
the Environmental Policy Act of 1970, management for a
diversity of values is appropriate for National Forest lands.
Legal, Congressional, or administrative mandates aside,
providing a diversity of uses on public land seems appropriate. Determination of which uses to provide and where to
provide them must be based on the land's capabilities and
human and wildlife preferences for various landscape features. Within pinyon-juniper ecosystems, the sum ofsuccessional stages or the sere is a major component of capability.
Capabilities of a sere vary with ecological units.
Pinyon and juniper trees themselves are obvious and
meaningful indicators of values related to different seral
stages. However, mature stands of these trees can obscure
variability in capabilities related to other successional stages.
The capacity of pinyon-juniper to dominate plant communities is so complete that West and Van Pelt (1984) used the
term "super dominance" in reference to their ability to
greatly oppress understory species and outlive the seed
banks of these species. Thus, describing potential uses of
pinyon-juniper ecosystems in terms of climax vegetation
(pinyon-juniper overstory with depleted understory) is
In: Monsen, Stephen B.; Stevens, Richard, camps. 1999. Proceedings:
ecology and management of pinyon-juniper communities within the Interior
West; 1997 September 15-18; Provo, UT. Proc. RMRS-P-9. Ogden, UT: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research
Station.
Sherel Goodrich is Forest Ecologist, Ashley National Forest, Vernal, UT
84078.
164
unsatisfactory because it gives little indication ofwhat other
vegetative mixes can occur in the sere (Hironaka 1987), and
therefore what other values could be provided. Use of geology, geomorphology, gradient, aspect, vegetation, soils and
other features as descriptors of ecological units provides a
broad base for classification and inventory (Wertz and Arnold
1972) that is not dependent on climax vegetation. Such an
approach to classification and inventory has been used in the
Green River corridor of Daggett County, Utah, which is the
focus of this paper.
Pinyon-Juniper Successional
Stages of the Green River
Corridor
To facilitate a discussion of capabilities and values, I
present some features of different successional stages. The
successional sequence is patterned after Erdman (1970),
Everett (1987), and Barney and Frischknecht (1974). This
sequence appears to be highly applicable to pinyon-juniper
woodlands of the Green River corridor. Successional patterns explained by Everett (1987)-including depletion of
the understory with increase in pinyon-juniper cover and
eventual purging of the understory when mature pinyonjuniper reach potential crown closure-are highly applicable in the Green River corridor (Huber and others, these
proceedings). West and VanPelt (1987) noted that successional stages are not isolated stages but points along a
continuum. However, the concept of stages can facilitate
communication. Features given are those observed and
measured in the Green River corridor and are not necessarily those given in the above cited works.
Fire and Skeleton Woodland
Crown cover-Live crown cover is reduced to zero or
nearly so.
Structure-Pinyon-j uni per are red uced to skeletons wi th
fines less than 1 or 2 cm in diameter mostly removed. Pinyon
begin to fall within the first 10 years after fire, while many
juniper skeletons remain standing for three or more decades. Herbaceous species and many shrubs are consumed
to near ground level or nearly so.
Plant composition-The community looks totally devastated without apparent composition.
Years-If burned before closure of mature pinyonjuniper has purged the understory, the blacked surface of
USDA Forest Service Proceedings RMRS-P-9. 1999
the skeleton woodland persists only until precipitation and
warm temperatures activate sprouting species and the seeds
of seed banks. Where closure of pinyon-juniper has purged
the understory and where the site is not seeded, the black
and desolate appearance might persist for 1 to 2 years while
invasive species, including cheatgrass (Bromus tectorum),
respond to the open site.
Annual
This stage is essentially skipped over where stands are
burned before the understory has been greatly reduced by
pinyon-juniper closure.
Crown cover-Crown cover of exponentially increasing
annuals including cheatgrass increases rapidly. Long-lived
seed banks such as those of a few mustards (Brassicaceae)
and annual chenopods (Chenopodiaceae) add to crown cover
in some stands. Crown closure of 60 to 80 percent can be
achieved in 5 to 10 years. This rapid crown closure of ann uals
is greatly facilitated by cheatgrass.
Structure-Structure is limited to the skeletons of the
trees and the annual herbaceous layer.
Plant composition-Annuals dominate the community.
These incl ude cheatgrass, Japanese chess (Bromusjaponicus
Thunb.), tansy mustard (Descurainia pinnata [Walt.] Britt.),
false flax (Camelina microcarpa Andrz. in DC.), Jim Hill
mustard (Sisimbrium altissimum L), prairie pepperweed
(Lepidium densifolium Schrad.), narrow leaf goosefoot (Chenopodium leptophyllum (Moq.) Wats.), wild tobacco (Nicotiana attenuata Torr. ex Wats.), knotweed (Polygonum
douglassii Greene), floccose gilia (Gilia inconspicua [Smith]
Sweet), Russian thistle (Salsola spp.), annual cryptanths
(Cryptantha spp.), blue-eyed Mary (Collensia parviflora
Lind!.), and western stick seed (Lappula occidentalis [Wats.]
Greene). Biennials and short-lived perennials such as hoary
aster (Machaerathera canescens [Pursh] Gray) are sometimes also a part of this early successional stage.
Of the seed bank species: wild tobacco is particularly
noteworthy. Where it has not been seen prior to burning, it
has expressed itself in abundance the year after fire. Within
3 years of abundant expression after fire, this plant is
commonly not seen again. This indicates the production of a
seed bank that is activated only by fire or perhaps other
disturbance. Life ofthe seed bank for this species is indicated
to be at least several decades and possible up to 200 years.
Also, invasive species with highly mobile seeds are able to
colonize these communities. Mobile seeds and aggressive
colonization are features of prickly lettuce (Lactuca serriola
L.), and introduced thistles including Canada thistle (Cirsium
arvense [L.] Scop.) and musk thistle (Carduus nutans 1.)
which are classed as noxious weeds in several Western
States.
Ground cover-Ground cover is reduced to near zero
percent with fire. Were high percent crown closure of pinyonjuniper was associated with a purged understory, ground
cover is comparatively slow to develop and is much a function cheatgrass and other annuals and the litter they produce. Cheatgrass can be quite effective in producing ground
cover, but the quality of this cover for watershed protection
is of somewhat lower value than that of perennial species.
USDA Forest Service Proceedings RMRS-P-9. 1999
Years-With highly competitive species such as
cheatgrass, this stage can persist for 20 years and much
longer where the perennial understory had been purged by
closure of mature pinyon-juniper stands. On southerly exposures of the Green River corridor, cheatgrass has been found
as the dominant 80 years postfire (Goodrich and Gale, these
proceedings) where it appears it can persist as the dominant
until pinyon and juniper return as dominants. This annual
stage can also be perpetuated by frequent fires that are
fueled by an abundance of cheatgrass.
Perennial Grass/Forb
This community can follow directly after fire where closure of mature pinyon-juniper has not purged perennial,
understory plants.
Crown cover-This remains a function of herbaceous
species.
Structure-Structure is limited to the skeletons of the
trees and the herbaceous layer.
Plant composition-Bluebunch wheatgrass (Elymus
spicatus [Pursh] Gould) with as many as 40 other herbaceous species form communities on northerly (cool) exposures. Communities with fewer species form on warm (southerly exposures). These include: Indian ricegrass (Stipa
hymenoides R. & S.), bluebunch wheatgrass, Ross sedge
(Carex rossii Boott), needle-and-thread grass (Stipa comata
Trin. & Rupr.), Sandberg bluegrass (Poa secunda Pres!.),
and hairy golden aster (Heterotheca villosa [Pursh] Shinn.).
Ground cover-Quality and quantity (including dispersion) of ground cover rapidly improves to provide adequate
soil and watershed protection where closure of preburn
pinyon-juniper communities had not greatly impaired the
understory. Seeding has been highly successful in establishing high percent ground cover within 5 years postfire where
the understory had been purged. Quality and quantity of
ground cover is a function of numerous fine-stemmed, closely
spaced perennial plants and the litter they produce.
Years-Rapidity of development of perennial grass/forb
communities highly depends upon closure ofpinyon-juniper
prior to burning and the dynamics of cheatgrass and other
invasive species after burning. Heavy infestations of
cheatgrass especially on warm exposures can delay the
dominance of these communities for 20 or more years and
much longer where they are not seeded. Many of the other
annuals decrease rapidly with the development of perennial
communities. Without seeding and with little or no cheatgrass
competition, this community is usually well developed within
3 years postfire. With seeding this communities can be well
developed within 2 years postfire even with strong presence
of cheatgrass.
Shrub/Grass
Shrub/grass communities can develop immediately after
fire where closure of mature pinyon-juniper have not purged
the understory of sprouting shrubs and herbaceous species.
Crown cover-Crown cover rapidly increases where
sprouting shrubs and herbaceous species were not purged by
165
closure of mature pinyon-juniper stands prior to fire. Crown
cover of sprouting shrubs can be near preburn levels within
seven growing seasons after fire where combined crown
cover of pinyon and juniper was only about 10 to 15 percent
prior to fire (Huber and others, these proceedings). Where
combined cover of pinyon-juniper was as high as 60 percent
prior to fire, shrub crown cover is often less than 2 percent
10 years postfire. In the absence of sprouting shrubs, shrub
recovery is slower with crown cover sometimes reaching 20
percent or more in about 30 years postfire.
Structure-Tree skeletons and especially those ofjuniper provide some structure. Shrub layers become more
complex with taller shrubs such as alder-leaf mountain
mahogany (Cercocarpus montanus Raf.) and serviceberry
(Amelanchier alnifolia Nutt.) overtopping big sagebrush
(Artemisia tridentata Nutt.), snowberry (Symphoricarpos
oreophilus Gray), yellowbrush (Chrysothamnus viscidiflorus
[Hook.] N utt.), and other lower shrubs with an understory of
herbaceous species. Bitterbrush (Purshia tridentata [Pursh]
DC.) increases in some places usually after big sagebrush.
Plant composition-Herbaceous species are the same
as for the perennial grass/forb stage with shrubs including
those listed above becoming more dominant.
Ground cover-Ground cover has generally reached
potential prior to this stage, and it remains at or near
potential through out this stage. With numerous finestemmed perennial plants closely spaced, quality and quantity of ground cover are of high value for soil and watershed
protection.
Years-This stage persists for up to 50 or more years
postfire with some minor return of trees where crown cover
of these trees remains less than 3 percent.
Shrub/OpenTree
Crown cover-In this stage crown cover of pinyonjuniper increases to about 20 percent. Everett (1985) found
a linear decrease in cover of understory species from about
5 to 20 percent crown cover of pinyon-juniper. However,
visual appearance of crown cover of shrubs and herbaceous
species remains about the same as for the shrub/grass stage
until pinyon-juniper crown cover reaches about 10 percent.
Structure-Structure of the shrub and herbaceous layers remains diverse. A prominent feature of this stage is
trees with dense limbs that extend to ground level. These
young trees add another tall layer, and they contribute to the
diversity of lower layers of structure. Return of trees is
typically uneven aged, and thus trees of various ages contribute to structural diversity. This appears to be the most
complex or diverse structural canopy stage in the sere.
However, it does not provide large boles and soft wood of
decay needed by cavity users to excavate cavities. Also, this
stage does not provide tall trees with large limbs preferred
by some birds including raptors.
Plant composition-Other than the addition of pinyonjuniper, composition remains similar to the previolls stage.
Although some understory species decrease, few are forced
out of the community.
166
Ground cover-Ground cover remains at high value for
soil and watershed protection.
Years-This stage is common from 60 to 100 years postfire.
Tree/Shrub Stage
This stage is not separated from the previous stage by
Erdman (1970) or by Barney and Frischknecp.t (1974). It is
separated in this paper for management implications. Fire
or other treatment applied to the previous stage will maintain a more resilient understory than if applied to this stage.
Crown cover-Combined crown cover of pinyon and
juniper increases from about 20 to 40 percent with a pronounced decrease in crown cover of shrubs and herbaceous
species. Sagebrush often becomes decadent while bitterbrush, alder-leaf mahogany, serviceberry, and snowberry
persist longer with greater apparent vigor, but they also
show reduced numbers, crown size, and vigor.
Structure-Tree structure incl udes dense limbs to near
ground level with larger bole and limbs than in the previous
stage, but still hardly of size and sufficient decay to be
selected by cavity nesting species and larger birds for nest
sites. However, due to the uneven age oftrees, some begin to
provide this larger structure. During the latter part of this
stage, pruning of lower limbs of juniper and especially
pinyon is generally initiated, and some trees begin to appear
mature. Structure of the shrub and herbaceous layers declines. Return of trees is typically uneven aged, and thus
trees of various ages contribute to structural diversity.
Skeletons of trees continue to provide some structure, but
they become less conspicuous as they fall and as live trees
increase.
Plant composition-Understory species present in previous stages begin to be purged from the community. Purging continues throughout this stage during which sagebrush
and other species can be eliminated or nearly so.
Ground cover-As the understory is purged, quality and
quantity of ground cover is decreased partly as a function of
lower dispersion of ground cover. As trees mature, they draw
more resources of the site into the area of their crowns.
Plants in interspaces begin to thin and bare soil is exposed.
Litter is increasingly confined to directly beneath the trees.
Years-This stage is common from about 100 to 200 years
postfire.
Mature Pinyon-Juniper
Crown cover-Combined crown cover of pinyon-juniper
is typically greater than 40 percent and can be as high as 60
percent or more.
Structure-Structure is largely a function of trees with
large boles, large limbs, and more open and larger crowns
than in previous stages. Also, decay within large boles
increases with age, which is important to cavity using
wildlife species. Some younger or smaller trees persist.
However, large and small trees are usually pruned oflower
branches over time. Purging of shrub and herbaceo us layers
USDA Forest Service Proceedings RMRS-P-9. 1999
is completed in this stage with sagebrush generally going
first and bitterbrush and mountain brush species persisting
longer.
Plant composition-Purging of the understory is carried to a high degree with relatively few individuals of
comparatively few species remaining. Shrubs are often totally purged. Remaining herbaceous species include Sandberg
bluegrass, Ross sedge, rock goldenrod (Petradoria pumila
[Nutt.] Greene), and pussy toes (Antennaria microphylla
Rydb). Cheatgrass remains in the community at low levels.
The nearly ubiquitous distribution of this species indicates
it will dominate the early part offuture seres throughout the
pinyon-juniper belt of the Green River corridor.
Ground cover-Interspaces become nearly void of plant
and litter cover especially on southerly aspects. Where sites
are productive enough to support -dense trees with the
crowns essentially continuous, a nearly continuous duff
layer can develop. However, more commonly large, bare
interspaces develop and persist in this stage in which rills
and sheet wash reach the highest levels in the sere except for
the fire and skeleton stage.
Years-This stage persists from about 200 years postfire
and until the next disturbance.
Capabilities and Values
Capabilities are a function of climate, geology, soils, gradient, aspect, plant taxa, variability of seral and mature
plant communities, and other ecological features particular
to a specific site. Values are a function of animal reaction to
these features and human perception and preference for
points of a sere.
The sere is a major expression of capabilities. Each stage
of succession is capable of supporting a different set of needs
for wildlife and other values. Wildlife might also be used to
define capabilities. However, composition and percent crown
cover and structure of vegetation and forage provided by
vegetation function well to define wildlife capabilities, for
these are features to which wildlife species respond. Some
species also respond to geologic structure such as rock
outcrops. Visual values are also a function of geologic features as well as vegetation, and they should be included in
an evaluation ofland capabilities. With a broad spectrum of
geological substrates, soils, aspects, and seral communities,
pinyon-juniper woodlands present a wide array of capabilities and values.
Breeding bird surveys from the Green River corridor show
a relatively high value of mature pinyon-juniper woodlands
for high diversity of species, total number of birds, and for
obligate and semiobligate species (Paulin and others, these
proceedings). Other workers have also found similar pinyonjuniper obligates and semiobligates (Cherry 1982; Balda
and Masters 1980; Fitton 1989). These include bark-gleaning, cavity-nesting insectivores such as chickadees (Parus
spp.) and plain titmouse (Parus inormalus) and those dependent on seeds of pines and junipers for food. Some small
mammals such as pinyon mice (Peromyscus truei) have been
found in pinyon-juniper dominated stands and not in early
seral communities (Sedgwick and Ryder 1987). Mature
stands also provide hiding and thermal cover for mule deer
USDA Forest Service Proceedings RMRS-P-9. 1999
(Odocoileus hemionus) and elk (Cervis canadensis). However, without forage openings, pinyon-juniper ecosystems
are oflow value for deer and elk and thus for large predators
such as cougars (Felis concolor). Also high val ues for fuelwood
and fenceposts are associated with mature pinyon-juniper
stands. Some recreational activities (picnicking and summer camping) are greatly facilitated by shade of mature
stands.
Bighorn sheep (Ovis canadensis) in the Green River corridor strongly favor early seral stages without visual obstructions of trees and tall shrubs (Smith 1992; Greenwood and
others, these proceedings). However, these sheep also prefer
steep slopes with a presence of cliffs and ledges that they use
to escape predators. Thus, early seral communities in and
adjacent to this essential escape habitat have high value for
bighorn sheep while such communities at a distance from
this essential escape terrain have low value. Pronghorn
antelope (Antilocarpa americana) are also ungulates of open
places that avoid cover of woodlands and forests. However,
in contrast to bighorn sheep, pronghorn prefer low gradient
plains and plateaus. Pronghorn have also responded positively to early seral communities maintained by fire within
the Green River corridor. Sage grouse (Centrocercus urophasianus) highly favors shrub/grass/forb communities. As
pinyon -juni per replace sagebrush communities, habitat val ue
for these birds is greatly decreased. Some small mammals,
such as deer mice (Peromyscus maniculatus), are more
common in early successional communities (Sedgwick and
Ryder 1987). The abundance ofthese animals can be important to birds of prey and other predators.
Value of yearlong and especially winter range for elk and
mule deer is greatly increased by the presence of shrubs wi th
stature that exceeds snow depths and have higher levels of
protein and other nutrients than do grasses and forbs in
winter. Highest value deer and elk range includes shrub/
grass and shrub/open tree communities or mid seral stages
intermingled with patches of mature trees that provide
thermal cover. Although some birds prefer mature pinyonjuniper communities, others including hawking or foliage
gleaning, cup-nesting insectivores such as the blue-gray
gnatcatcher (Polioptila caerulea), black-throated gray warbler (Dendroica petechia), and gray flycatcher (Empidonax
wrightii) (Ehrlich and others 1988) are favored by presence
of shrubs. Vesper sparrow (Pooecetesgramineus) and Lazuli
bunting (Passering amoena) are also associated with mountain shrub species of mid seral communities. Also birds
typical of sagebrush formations are also found in stages with
an abundance of sagebrush such as the sage sparrow
(Amphispiza belli) and Brewer sparrow (Spizella breweri)
(Behle 1981). A shrub component can increase abundance of
insects used by many bird species including jays (often
considered seedeaters) to feed their nestlings.
Trees most likely to be selected for Christmas trees are
most likely to be found in shrub/open tree and tree/shrub
communities.
Seeds of pinyon and juniper have value for a number of
wildlife species including birds ofthe Corvidae family (Balda
1987). Pinyon nuts have value for personal and commercial
use. Generally, seeds are not part ofthe sere until the shrub/
open trees stage. They are most abundant in the tree/shrub
and mature pinyon-juniper stages.
Recreation and visual values can be expected to vary with
individuals and their various activities. Bird watching and
167
study of birds are indicated to be at highest value in tree/
shrub and mature stages. Viewing and hunting bighorn
sheep, elk, deer, and antelope will be facilitated by maintenance of early and mid seral communities. Personal use
Christmas tree harvest is a form of recreation for which
shrub/open tree and tree/shrub stages are of highest value.
Visual qualities can be expected to be highly variable with a
diverse viewing public. Perhaps a diversity of stages across
the landscape will address this value. Sometimes values
expressed by humans run opposite to those favorable for
some wildlife species. People often object to standing dead
trees left after fire. However, these dead trees provide some
cover and structure for wildlife. Also, this human view is not
well supported by the ecological history of pinyon-juniper
ecosystems that included standing, burnt trees. Objections
are also expressed for the blackened and desolate look
following fire and the broken debris- following mechanical
treatments. However, habitat for early and mid seral wildlife and plant species cannot be maintained without treatments t~at reduce trees. The debris left in place following
mechamcal treatments can have high value for watershed
protection (Farmer 1995).
Erosion hazard is related to successional stages. In the
perennial grass/forb stage and midseral stages, the ground
IS covered by many fine stems of vegetation that are closely
spaced and by litter that has a high dispersion value. Mature
pinyon-juniper stands tend to have large interspaces of high
percent bare ground. This condition is especially noticeable
on steep, southerly (warm) exposures in the Green River
corridor (Goodrich and Reid, these proceedings). The warm
aspects have potential for higher value for mule deer and elk
forage in winter than cool exposures due to less depth and
duration of snow cover. However, mature stands have much
lower value for forage for these animals than do early and
mid successional stages. Thus, both watershed and ungulate
forage values for these slopes can be higher at early and
midseral stages than at the mature stage.
Vigor and diversity of understory communities remains
quite high thorough the shrlJb/open tree stage and then
declines thorough the tree/shrub stage, and it is greatly
reduced in the mature stage (Huber and others, these
proceedings). Vigor of the understory community is critical
t~ the resilience of native plant communities following
dIsturbance. Recovery of native communities can be quite
rapid following fire in the perennial grass/forb through the
shrub/open tree stages. Recovery of native plant communi~ies. is much slower following disturbance in mature pinyonJumper communities. This feature of pinyon-juniper woodlands h~s become critical with the advent of cheatgrass,
musk thIstle, and other highly invasive introduced species.
COl~pled with the nature ofpinyon-juniper to greatly oppress
native understory species and outlive the seed banks of
these species (West and Van Pelt 1987), the explosive ability
of cheatgrass to increase after disturbance (Young and
Evans (1978) presents a scenario in which it is difficult to
apply a concept of native plant communities. Disturbance is
us ually a matter of "w hen" more than of "if." When disturbance comes to mature and old stands of pinyon-juniper, the
stands are left wide open to the invasion of cheatgrass and
other invasive weeded species by the general lack of native
understory species, which is a function of pinyon-juniper
stand closure (Everett 1987; West and Van Pelt 1987).
168
Diverse plant communities develop in early and mid seral
stages of succession where in dense mature stands of pinyonjuniper understory communities are often of low diversity
and members of these communities are of low frequency.
However, mature and old stands provide structural features
not found in earlier stages.
Intrinsic values are sometimes raised as an issue. Each
plant community has intrinsic value, and the value of each
stage can vary widely within a diverse public. This ambiguous value is included in the other more specific values
addressed above.
Ecological Units
Management for diversity of values will be well served by
an understanding of capabilities. Hironaka (1987) suggests
the trees themselves do not provide a bases for classification
and their suppression of understory species often prohibit~
classification based on the understory. Classification, inventory, and documentation of community features based on
more than the end point of a sere are critical to understanding values and capabilities.
A Land Systems Inventory has been developed for part of
the Green River corridor based on geology and geomorphology with gradient, aspect, soils, vegetation, and other features also used as descri ptors of ecological uni ts (Wertz and
Arnold 1972). Classification is an inherent part of this
inventory. The inventory also includes some information on
capabilities and values of different ecological units. As more
information is acquired through studies, research, observations, and experience, this is added to the inventory. Such a
"living inventory" seems vital to adaptive management.
This paper and other papers referenced in this paper dealing
with the Green River corridor can be used as a part of the
database of the Land Systems Inventory.
Managing for various values can be greatly facilitated by
information about the capabilities of various land units
within a landscape. Without specific examples this concept
seems to remains rather empty. Thus, specific examples
from the Green River corridor are used in the following
discussion.
In this area, soils, vegetation, visual values, and wildlife
habitat are much a function of geologic features. These
features are basic to an evaluation ofland capabilities. Basic
to management of the pinyon-juniper belt is the considera tion of how much of each successional stage is desired and
where on the landscape these stages should be emphasized.
A equal portion of each stage or some other mix of stages as
suggested by Amundson (1996) may be satisfactorily defined
in a conceptual or programmatic manner without considering where on the landscape each stage is to be emphasized.
However, a random assignment of succession stages to
actual parts of the landscape without regard to inherent
capabilities of different ecological units within the landscape does not appear to be the most effective way to achieve
a desired mix.
An evaluation of lands within the context of the Land
Systems Inventory indicates different successional stages
may be more appropriate for different land units. Based on
a dominant feature of ridge and ravine topography as a
function of differential weathering of geologic strata at the
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flank of the Uinta Mountain uplift, a landtype association
referred to as "Structural Grain" was identified in the Land
Systems Inventory. The Red Canyon gorge of the Green
River was identified as "Red Canyon" LandtypeAssociation.
Nearly all of the Structural Grain Landtype Association and
southerly exposures of the Red Canyon Landtype Association support pinyon-juniper communities or have the capacity to do so. Landtypes within these associations have been
identified by number. This inventory is consistent with the
concept of ecological units as defined within a National
Hierarchical Framework of Ecological Units that has been
adopted by U.S. Department of Agriculture, Forest Service
as discussed by McNab and Avers (1994). They also fall
within the concepts of Godfrey (1977), Godfrey and Cleaves
(1991), and Wertz and Arnold (1972). A discussion of all
ecological units identified for the pinyon-juniper belt of the
Green River corridor is beyond page limitations for this
paper. Following are three examples ofthese ecological units
and management implications based on capabilities and
values.
Structural Grain Landtype 2 Ecological
Unit
Features-The landtype consists of ridge and ravine
topography underlain by the Uinta Mountain Group, which
includes shale and quartzitic sequences. The shale and other
more easily eroded units have been eroded to produce the
ravines, while the more resistent beds form ridges. The
ridge/ravine sequence has a general east-west direction with
northerly (cool) and southerly (warm) exposures of about 20
to 40 percent slope. The shrub/open tree stage of the cool
exposures incl udes alder-leafmountain mahoganylbluebunch
wheatgrass communities with as high as 40 or more herbaceous plant species and often five or more shrub species
(Huber and others, these proceedings). Within the Green
River corridor, this diverse community is nearly unique to
the Structural Grain Landtype Association. Earlier stages
ofsuccession on southerly exposures su pport Indian ricegrass,
bluebunch wheatgrass, and a few other herbaceous species
followed by mountain big sagebrush and rubber rabbitbrush. Seral communities of both cool and warm aspects can
be essentially purged under mature stands of pinyon-juniper. The soil surface of cool aspects is well mantled by
vegetation and litter through the shrub/tree stage and often
by a layer of duff under the dense canopy of mature pinyonjuniper. The soil surface of warm aspects is moderately to
highly protected by vegetation and litter in the perennial
grass/forb through the shrub/open tree stage. However, as
pinyon-juniper increase, the understory is depleted and
ground cover decreases to the duff found under the canopies
of trees with the interspaces nearly barren. Low watershed
values can be associated with mature and old pinyon-juniper
stands on the warm aspects (Goodrich and Reid, these
proceedings) .
These warm slopes can have comparatively high value for
wild ungulate forage in winter because depth and duration
of snow cover is less here than on cool exposures. However,
the shrub stages of the cool exposures also have high value
for wintering wild ungulates due to the abundance of taller
shrubs including alder-leaf mountain mahogany and servi-
USDA Forest Service Proceedings RMRS-P-9. 1999
ceberry. Much of the landtype is far enough removed from
high value bighorn sheep escape terrain that it generally has
low value for these animals. However, parts ofthe landtype
are close enough to escape terrain to be of high value for
bighorn sheep.
Management Implications-The diversity and uniqueness of shrub/grass and shrub/open tree stages indicate high
value for maintaining these stages on this land type. These
communities have high value for wintering mule deer and
elk and for some birds and small mammals favored by
shrubs. Long-term occupancy of mature pinyon-juniper
stands deplete and eventually purge the understory. Where
shrub/open tree communities are now present on the landscape, maintenance of the understory is indicated as high
priority for management. Maintenance will require fire or
other disturbance that reduces trees before shrubs, grasses,
and forbs lose the ability to rapidly recover. Some stands
where the understory is already purged include large boles
and crowns in the structure. These serve to provide overall
diversity and values associated with mature stands.
The apparent high value for winter forage for wild ungulates of early to mid successional stages of the warm, southerly exposures coupled with the erosive nature of some of
these slopes under mature pinyon-juniper indicate high
value for perennial grass through the shrub/open tree stages.
Capabilities and values of this ecological unit strongly
indicate primary emphasis for early to mid seral communities. This emphasis should not preclude some mature stands.
A fire return interval of 100 to 150 years is indicated to
maintain these seral stages (Goodrich and Barber, these
proceedings) .
Structural Grain Landtype 7 Ecological
Unit
Features-High frequency of scarp and dip slopes is
typical of the landtype. The scarp slopes (of southerly exposure) often include cliff faces. The dip slopes (of northerly
exposure) frequently have bed rock at or near the surface.
Many pinyon-juniper trees are large and 200 to 300 years
old. Some are over 400 years old. Understory vegetation is
sparse. The highly diverse mountain brush com~unities ~f
Structural Grain Landtype 2 are generally lackmg on thIS
landtype. However, bitterbrush is often present, and it
increases with reduction in tree cover.
Currently nearly all of this ecological unit supports mature and old stands of pinyon-juniper. Ponderosa pine (Pinus
ponderosa Laws.) is also occasionally to locally common on
the landtype, which provides another layer of canopy a~d
another dimension to woody structure. Large trees of pmyon, juniper, and ponderosa pine indicate high value for
cavity nesting species. The large crowns and diverse layers
of canopy provided by these trees indicate high value for
many bird species and some small mammals. High percent
rock at the soil surface and in the profile provide stable
watershed conditions under mature stands of trees. A large
unit of the landtype is adjacent to Flaming Gorge Dam. It is
dissected by a National Scenic Highway (Highway 191) and
by power transmission corridors. It is also near the town of
169
Dutch John. These features indicate difficulty for prescribed
burning and other management practices.
Management Implications-Inherent and imposed features of this ecological unit strongly indicate emphasis for
mature and old stands. Old trees on the landtype indicate a
fire return interval of greater than 200 years to be an
inherent part of the ecological history of the landtype.
Increased recreation use associated with Flaming Gorge
Reservoir presents a higher potential for fire than that
under which these stands developed. Fire suppression could
be helpful and seems appropriate in maintaining greater
than a 200 year fire return interval.
Red Canyon Landtype 1 Ecological Unit
Features-The gorge of Red Canyon carved by the Green
River is the prominent feature of this landtype. It includes
massive cliffs of Pre cambrian q uartzitic materials and shales
of the Uinta Mountain Group. Also included are steep, rocky
slopes of mostly greater than 40 percent slope. Southerly
(warm) exposures dominate the landtype. Daytime temperatures well above freezing are common in midwinter on
some of these slopes. Abundance of escape terrain and
aspects that are warm in winter indicate high value for
bighorn sheep. Smith (1992) and Greenwood and others
(these proceedings) found warm aspects of Red Canyon to be
highly selected by bighorn sheep. Such aspects are also
conducive to abundance of cheatgrass (Goodrich and Gale,
these proceedings). The winter annual habit of cheatgrass
indicates high forage value of this plant for bighorn sheep.
These sheep have been observed in winter on the landtype
with green muzzles from feeding on wintergreen cheatgrass.
However, cheatgrass does not provide nutritional needs in
all seasons ofthe year. Maintenance of a diverse forage base
will better meet the needs of these animals. Timely use offire
and seeding perennial species are important to maintain a
balanced forage base. Evidence of past fire is common on the
landtype. However, in many places rock cover is high and
density of vegetation is sparse. In these areas fire frequency
and size are expected to be low due to rock cover.
Management Implications-Pinyon and juniper have
the ability to displace all other plant communities in the
absence of fire or other disturbance. The high value of this
landtype for bighorn sheep indicates emphasis for early
seral communities with low presence oftrees and tall shrubs.
A fire return interval of less than 80 years is indicated for
achieving and maintaining high value habitat for bighorn
sheep.
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