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Abstract-This paper summarizes 17 excellent, detailed papers presented during the section of the symposium on the resource values of the pinyon-juniper woodlands. James E. Bowns captures the salient points of each paper, a formidable task that required that most of the detail be left out. The reader is encouraged to read the complete papers for additional details.
Pinyon-juniper species are a sizable wood fiber resource for products that can be made from smaller, irregular stems and those that can capitalize on the unique physical and chemical characteristics of these species.
Firewood obtained from pinyon andjuniper has been used longer and more extensively than any other product. This is still the main fuel in many rural areas as well as urban use in wood burning stoves and fireplaces. These species have excellent fuel wood characteristics of heat content, ignition, flaming, and fragrance.
Juniper posts have historically been used because of their easy access and natural durability. A good post can last 60 years, and the diameter ofthe heartwood is the determining criterion for durability. Juniper is also used for stub posts in power and telephone lines and highway guard rails. Young and intermediate aged stands provide the best posts. Pinyon is not favored for posts because they are not of suitable form or durability.
Pinyon andjuniper and not widely used for sawn products because of the poor growth form and small size. Other problems include high wood density and grit in the bark that causes excess saw wear and resin build up.
Railroad ties and mine timbers are some of the usable products and are superior to those obtained from local softwoods. Furniture and novelty items (book ends, lamp bases, clocks, jewelry boxes, and small chests) capitalize on the unique fragrance, color, and grain patterns of these woods.
Particle board can be made from both pinyon andjuniper.
Juniper is somewhat better because of its specific gravity,
In: Monsen, Stephen B.; Stevens, Richard, comps. 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.
James E. Bowns is Range Ecologist, Southern Utah University, Cedar
City, UT 84720. texture, color, and fragrance. Markets still need to be developed for these products.
Cement board can be made with cement, wood fiber, and water. It is fire resistant, relatively unaffected by water, and can be worked like particle board.
Charcoal can be made from all species of pinyon and juniper; however, more dense woods such as gambel oak are superior. Charcoals made from pinyon and juniper were used as smelter fuel in early mining operations.
Although some species of juniper have proven satisfactory for pulp, it produces low yields. Other problems are that the pulp is too difficult to bleach for white paper, too weak for unbleached high-grade bag and wrapping paper, and too soft for corrugating board. Economic feasibility for pulping pinyon-juniper in the region is questionable.
Pinyon wood contains large quantities of oleoresin or gum.
Products obtained from the resin include spirit, linseed oil, tung oil varnishes, ester gum, and zinc resinate. The Zuni
Indians use the resin for an antiseptic, pottery glaze, and for burning in religious ceremonies.
Juniper woods contain large quantities of oily fragrant extractives rich in cedrol and associated essential oils. Other compounds should include terpene and sesquiterpene. J uniper foliage also contains fragrant oily extractives.
Other important products include pine nuts and Christmas trees. Nut production is highly variable from area to area and year to year, which ca uses problems for nut brokers and processors. Pinyon Christmas trees are favored by many residents of the Interior West. The single needle pinyon is generally favored because it is more symmetrical.
Resources such as food, shelter, tool construction, tinder, and preferred settlement locations are available in the pinyon-juniper woodlands. These woodlands provided aboriginal peoples some of the most basic raw materials for sustaining life.
Pine nuts were one ofthe most important foods of the early inhabitants ofthe Great Basin and Colorado Plateau. These nuts were gathered in large quantities and were considered the single most important food species where they occurred.
The nuts are high in both protein and fats, the proportions
USDA Forest Service Proceedings RMRS-P-9. 1999 157

varying among species. The fat content exceeds that of chocolate and contains all 20 essential amino acids. Nuts provide tryptophan, which is deficient in diets of corn farmers.
Nut production varies from year to year, area to area, and age of the tree stand. Pinus monophylla is more productive and predictable than P. edulis. A casual relationship has been proposed between the unpredictability of pinyon pine nuts with the high residential mobility of the Great Basin people.
Nuts were harvested in the early fall at about the time of the first frost and eaten raw or toasted, hulled, winnowed, and ground into paste for making a pine nut soup or gruel.
Soup was sometimes mixed with meat to add flavor and
Navajos made nut butter, which was spread on corn cakes.
Nuts were stored in pits or other storage facilities that were lined with rocks, grass, or juniper bark and covered with bark, branches, dirt, and more rocks. This kind of storage ensured that the nuts would tast at least all winter.
Juniper "berries" were occasionally used for food. Apaches ate them fresh or pounded them for bread or juniper tea.
Utes ate the pulp fresh or dried, or used them as an ingredient in bread or stews. Great Basin people used juniper
"berries" sparingly, but they were occasionally eaten in the fall and winter after they were boiled.
The use of pinyon as medicine was limited, but the pitch and gum were boiled in water and drunk to purge worms and other parasites. Juniper leaves were used in teas for the treatment of colds and coughs.
Pinyon and juniper were used for house construction, hogans, sweathouses, ramadas, fences, corrals, drying racks, and storage facilities. These trees were also used for fire material or kindling wood.
J uni per bark was an integral element in roof construction, fiber for mats, diapers, menstrual pads, and cushioning and protective lining for storage pits.
Pitch was used to line basketry water jugs as a sealant, as glue for ceramic vessels, and as a mastic for attaching projectile points or stone tools.
Habitat values ofpinyon-juniper woodlands often receive little consideration because they appear so extensive that there seems little possibility of exhausting the supply, and the aridity and lack of vegetation diversity seems inconsistent with highly productive wildlife habitat. Also, land managers may consider mature pinyon-juniper undesirable or at least less desirable than earlier seral stages because of the lack of understory vegetation.
These woodlands support rich and distinctive bird communities and make substantial contributions to landscapelevel avian diversity. In northeastern Utah pinyon-juniper ranked second in percentage of obligate and semiobligate species, third in total number of individuals counted, and fourth in species richness and diversity. Only riparian areas had a higher percentage of obligate or semi obligate species.
Of seven upland forest habitats studied, pinyon-juniper ranked second in total individual birds and third in species richness and diversity. In general, the number of species and individuals tended to decrease with increasing elevation.
Consideration of more than simply the number of species is important because an area that supports· a few rare species can be as important as one that supports many common species.
Studies show that chaining can negatively affect the abundance of cavity nesters, timber gleaners, aerial foragers, and species that forage in or next to the foliage. Birds that nest or forage on the ground use both treated and untreated areas. Woodland treatments are not necessarily bad for birds, and creating a mosaic of seral stages provides the best balance of habitat features sought by birds. Shrubdependent and edge-associated species benefit from welldesigned treatments. Sites with high edge-to-interior ratios should be selected, and more trees should be left standing near the edge. This will add structural complexity and thus compensate for the loss of overstory.
Managers should also consider habitat values of mature woodlands when meeting watershed and forage production objectives. The best option appears to be a landscape designed to include functional patches of all seral stages.
In another study, 53 bird species, using pinyon-juniper woodlands for breeding, were observed on seven pinyonjuniper sites. Only two species, blue-gray gnatcatcher and black-throated gray warbler, occurred on all seven sites, and
77 percent were neotropical migrants. Researchers conclude that pinyon-juniper forests are important for the continued breeding success ofthese two species and the gray flycatcher.
Pinyon-juniper forests provide important food, cover, and nesting habitat for at least nine neotropical migrants, and the pinyon-juniper type supports a greater variety of birds than had been anticipated. However, the total number of species depending entirely on this type for breeding is low compared to other habitat types.
Sagegrouse depend upon sagebrush steppe throughout their distribution. The lack of fine fuels and more mineral soil has generally decreased fire frequency, although intensity has increased in some areas.
Sagegrouse populations have declined in much of their former range, and these declines are most notable where habitat limitations including loss, fragmentation, and degradation of sagebrush ecosystems have occurred.
Some sites have been treated with the brush beating of short (less than 1 m) pinyon and juniper trees, sagebrush, and associated deciduous shrubs. Taller trees were cut with chain saws, and some hand cutting removed trees from lek sites.
These treatments doubled sagegrouse populations, and the increase was attributed to the decreased mortality of males during the breeding season and improved survival of both males and females. Prior to the treatments raptors had hunted from the trees adjacent to the lek sites, and all documented sagegrouse mortality was attributed to predation by raptors. However, the effect of cutting trees was confounded because sagebrush beating also occurred at the
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lek sites, which increased the ability of the sage grouse to detect predators at greater distances. Pinyon and juniper trees were avoided from June through August, at which time sagegrouse selected treated areas that had an abundance of succulent forbs.
I t seems remarkable that sagegrouse populations respond so quickly to treatments designed to solve an immediate local problem. Outside of predation, mortality of this population appeared low and no hunting was allowed. It appears that tree removal can increase usable habitat size by at least
100 percent.
Small mammals are affected by juniper encroachment, conversion, and subsequent impact§) of community structural change. An estimated 341 animal species are found in the southeastern Oregon juniper steppe.
The number of captures is usually higher on cut sites.
Captures are higher on shrub sites than old-growth woodlands, and the structure provided by robust understory vegetation and overhanging juniper skeletons provides superior security and forage in the cut and dropped sites.
Leaving blocks of unchained vegetation should maintain woodland-dependent species while providing increased total numbers of small mammals in treated areas. Total captures and number of species are higher in cut sites than in uncut sites. This concurs with other studies that show that small openings can benefit a variety of wildlife.
Cut sites have preferred structure, which is provided by
~ncreased vigor (cover and height) of herbaceous species,
Increased seed production on cut sites, greater species richness, and juniper slash. Cut sites generally provide increased security and forage for small mammals.
Opening stands of western juniper and leaving trees or thinnings does not substantially affect small mammals. The
Great Basin pocket mouse appears to be the most sensitive species to the loss of shrubs during the latter seral stages.
Some species such as wood rats are favored by trees. For maximum structural diversity shrub steppe communities should be managed through early-to-mid-seral woodlands.
In late and closed woodlands, structural complexity and plant diversity results in shifts in small mammal population dynamics.
Fuel wood harvesting results in immediate, drastic, and abrupt habitat changes. Small mammals have intricate roles in ecosystem function, so they are a key component of pinyon-juniper woodlands.
Slash left on the ground results in an increase of some rodent population regardless of overs tory condition. This also affects microsite nutrient cycling, understory production, and regeneration of overstory species.
Overstory removal and slash accumulation seems to have more beneficial effects for deer mice specifically and other species as well. However, these two effects were detrimental to the pinyon mouse. Overstory is important to pinyon mice, and burning is of further detriment to this species.
Burning of slash is considered detrimental and may offset the beneficial effects of the slash. Small mammal populations are related to overstory adjustments or slash composition.
Mature Utah juniper "berries" are the most commonly taken food by gray fox in terms of percent relative frequency of occurrence and mean percent of volume in scats. Chemical analysis of juniper "berry" hulls indicates that they provide the basic supply of nutrients and minerals. Mature juniper
"berries" are low in moisture, which concentrates more energy and nutritional content into the hulls, therefore providing more value per unit weight than immature berries with high moisture content. The hulls alone provide the minimum gross energy needed for gray fox maintenance and then some. There may also be some zoopharmacological benefits of secondary compounds in purging external parasite loads.
Mammalian prey, mostly rodents and leporids, represent the majority of the diet not consisting of juniper "berries."
The addition ofthe mammalian prey likely supplements any nutritional deficiencies.
Gray fox contribute to community, structure, dynamics, and function of Utah juniper dominated ecosystems. Gray fox are efficient foragers that specialize in an interesting mix of vegetal and animal matter. The gray fox is the only mammal known to forage extensively on the hulls of juniper
"berries." The hulls comprised a large part of their diets during all seasons studied.
Mature juniper "berries" exist in large quantities and provide a large volume of readily available nutrition throughout the year. "Berries" ripen on the tree and persist for up to 2 years. Gray fox are adept at climbing trees and use junipers for a food source, resting, and escape cover.
Juniper seeds pass through the digestive system intact, and the metabolic residue in the scat provides the seeds with a natural mulch of nitrogen and other minerals. This possibly provides a valuable benefit to juniper community dynamics in the form of seed dispersal. An alternative view may be that this seed dispersal is detrimental because it increases the spread of juniper that may be interpreted as undesirable.
Apparently gray fox do not actively feed on pinyon pine nuts and acorns, which would require the breakdown of the shell or husk before they could obtain any nutritional benefit.
Rocky Mountain Bighorn sheep show a high preference for burned areas within pinyon-juniper and ponderosa pine communities, especially those burns located within or adjacent to steep, rocky habitat within core use areas. This positive response occurs in small or large burns.
Bighorn sheep generally avoid areas with a high density of live or standing dead trees, which reduce visibility to intolerable levels. In addition to high visibility, bighorns prefer older burns dominated by grass, which constitutes
79 percent oftheir diet. Early seral stages are more valuable to bighorns than tree dominated areas. Therefore, maintenance of bighorn habitat is highly dependent on repeated burning or bighorn densities will be low.
The distribution, abundance, and habitat affinities of amphibians and reptiles have been documented in pinyonjuniper woodlands. Four species of amphibians and 26 species of reptiles were found. Of the reptiles, 50 percent were snakes. The speckled rattlesnake and striped whipsnake
USDA Forest Service Proceedings RMRS-P-9. 1999 159

were the only snakes common throughout the zone, but the distribution of most snakes is still poorly understood. Seven species of reptiles extended into the bristlecone-limber pine zone.
Toads, frogs, skinks, and salamanders are found near springs, ponds, and seeps. This emphasizes the importance of wet areas for these species. The generally unrecognized diversity of herptofauna in these woodlands, along with specific research and management needs, have been documented.
Nearly all plants of Utah and other Western States that are listed as threatened, endangered, or sensitive are narrow endemics, which are defined as plants restricted to one or a few counties in one or perhaps two States.
Within the pinyon-juniper thermal belt plant generalists are found on nearly all geologic strata and soil types, but pinyon-juniper and desert shrub communities also support most of the narrow endemics in Utah.
Edaphic control of vegetation by geologic formations is greatest where geologic strata are exposed, and the area must be xeric in order for the substates to be controlling.
Dessication is apparently necessary for the ultimate expression of edaphic control, and this is not as common at higher precipitations. Water tends to override the influence of geology. Xeric conditions are also associated with steep slopes, clifffaces, and wind swept slopes where plant specialists are protected from the competition of generalists. Relatively few narrow endemics are found where the area is well mantled with vegetation. Therefore, Utah, with much exposed geology and xeric conditions, supports numerous, relatively narrow endemic plants.
Specific taxa have been arranged into three categories of apparent relationships to pinyon-juniper. Each taxon is named, the geology and soils !1re discussed, and notes are made on each species. These categories are (1) obligatory or semiobligatory to pinyon-juniper, (2) apparent associates mostly in the interspaces of trees and exposed geologic substrates, and (3) incidentals, which are found within the pinyon -j uni per but extend below into the sal t desert shrub or above the pinyon-juniper on wind swept slopes and ridges.
Apparently, narrow Utah endemics have evolved where geology and erosion are the primary drivers of plant community composition or dynamics, and these plants are unable to compete with generalists on well-developed soils. Narrow endemic plant population densities are often low, and survival is more a function of adaptation to harsh substrates and dry conditions than their ability to compete.
Semibarren habitats, which have low potential for vegetation manipulation, are occupied by these narrow endemics, and these species can be used as indicators of these low potential sites. Sites better suited for the high production of shrubs and herbaceous species are unsuitable for narrow endemics.
The strong relationship between highly erosive, geologic strata, and narrow endemics indicates an evolutionary situation dependent on harsh conditions and high rates of erosion. This condition predates the advent of Europeans and their livestock by thousands of years.
Most potential conflicts can be resolved where there are well-documented inventories and an understanding of the habitat requirements and biology of narrow endemics.
Old-growth pinyon-juniper woodlands do not fit the typical image of old-growth coniferous forests. However, some of the oldest stands throughout the Intermountain West are low statured, open, semiarid woodlands.
Old woodlands usually differ in structure and function from postsettlement woodlands, thus adding diversity at the community and landscape levels. Concern over the rapid expansion of these woodlands during the 20th century has overshadowed the presence and values of presettlement woodlands. In addition, wildlife studies have generally not separated postsettlement from pre settlement stands.
Pinyon-juniper woodlands should be defined on the basis of tree age and stand structure and function. One age separation may be on the basis oftree establishment prior to
European settlement. In the Great Basin rapid expansion of these woodlands coincided with settlement in the late 1860's and 1870's. Old growth can also be based on the structural characteristics of the trees. With age, canopy morphology shifts from a cone shaped to a rounded top. As trees age they may exhibit broad asymmetrical tops, deeply furrowed bark, twisted trunks or branches, dead branches and spiked tops, large lower limbs, narrow strips of bark, hollow trunks, large diameter to height ratios, and bright yellow lichens on the branches. Western and Utah juniper ages can exceed 1,000 years and pinyon 600 years.
At the community level, old-growth woodlands should be described on the basis of the presence of old trees and structural characteristics such as standing and down dead, decadent living trees, cavities,and lichen-covered branches.
The pinyon-juniper type has been described as climax with woodlands shifting to grasslands or shrub steppe only following a disturbance such as fire. In the absence of a disturbance, these communities will eventually return to woodland. Old-growth woodlands occur over a wide range of parent materials, soils, aspect, slope, elevation, climate, and disturbance regimes.
Ecological provinces may provide a first separation in the classification of old-growth woodlands. A current system considers: (1) community type based on ecological province, land form, dominant shrubs and grasses, soils, and topography; (2) tree age composition and structure; and (3) understory composition. Age classes are subdivided under presettlement and postsettlement categories.
Researchers have described 13 old-growth woodland types of prehistoric and presettlement distribution and changes, extent and proportion of old growth, soils, species composition, wildlife values, and other attributes.
What should old-growth stands be managed for? These old-growth woodlands make up only a small percentage of pinyon-juniper woodlands, and they are structurally and topographically more complex than the younger, more abundant
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woodlands. Old-growth is esthetically pleasing and provides recreational, cultural, and spiritual opportunities.
Fire policies influencing these old stands should be evaluated for both suppression and let burn. Fuelwood cutting has been considered wasteful unless cutting is designed to remove postsettlement trees and restore presettlement stand structure.
Studies are needed to determine and describe the range of old-growth woodlands. It is also important to evaluate presettlement and postsettlement changes in community structure and composition, define desired future conditions, and develop management plans for restoring or maintaining old-growth woodlands. These old stands are an important landscape component that support many plant and animal species, and interact with adjacent community types.
When juniper canopies begin to mature and close, microtopographic elements become more pronounced. Coppice dunes or mounds beneath the trees are evident. These dunes are higher under the trees than in the interspaces.
Within the interspaces, the soil surface can be as much as
1 m lower than at the trunk and are usually covered with gravel. Under the trees the soils are relatively fine-textured and incorporated with leaf litter. The dunes or coppices absorb the energy of flowing water and restrict the sediment delivery downslope.
One question is ifsites dominated by maturejuniper trees represent degraded or degrading systems. One postulation that juniper successional trajectories are currently in place and are likely to continue for centuries due to the longevity of these trees, resulting in a self-destructing system. Therefore, it is necessary to identify sediment source and sink relationships, which will help identify the need for custodial or active management.
Soil under the trees has an organic horizon that is absent in the interspaces. A petrocalcic horizon appears to restrict the downward growth of roots and impede water percolation and vertical nutrient flux. This horizon is deeper under the coppice dune and nearer the surface in the sparsely vegetatedinterspace. The sagebrush fluve has a weakpetrocalcic layer.
Preliminary findings suggest that horizonation is different between coppice dunes, interspaces, and sagebrush fluves, which might influence the distribution of vegetation.
Further studies of this problem are ongoing.
Removal of junipers has altered the hydrologic regime of several small watersheds, resulting in large increases in springs and water yields. A Coordinated Resource Management Plan was developed for the purpose of increasing and maintaining the availability and duration of surface flows, enhance ground water recharge, increase and maintain plant diversity, and structure and provide quality habitat for wildlife and livestock.
Chaining and seeding, wildfires, and prescribed burning have resulted in numerous seeps, wet meadows, and perennial springs emerging. Previously dry stream channels are developing into riparian areas. However, some negative effects are slope instability and seepage erosion.
The hypothesis proposed for this phenomenon is that most springs occur at points of subsurface flow concentration where a shallow soils mantle exists over low permeability bedrock such as shale or where water may flow through a confined aquifer of fractured bedrock or bedrock containing solution cavities. Flow might also be controlled by structural features such as faults.
Preliminary results suggest that most subsurface flow is through fractured bedrock that might create discrete packets of infiltration, transfer, and discharge. Unique geology of a site may force ground water to the surface, allowing increases in water yield to be readily exploitable.
New research is being developed to address the problems encountered when dealing with extremely variable site conditions and protracted time scales.
The specific objectives are to (1) establish a long-term watershed-scale research site on semi-desert and upland climate zones and (2) perform mechanistic research in pinyon-juniper woodlands that will study ecosystem dynamics such as energy flow, water and nutrient cycling, organismal structure and function, and sediment source/sink relationships. At the same time, the project will address the more pragmatic concerns associated with management objectives, the effects of drastic disturbances and the results of custodial management.
The design utilizes small watersheds and spatial nesting of tributary basins and provides integration of spatial and temporal variability on a realistic scale. Potential treatments will include (1) mosaic thinning, (2) simulated wildfire, (3) mechanical manipulation (chaining), and (4) an untreated control for evaluating carbon sequestration, seed dispersal and population dynamics, and social considerations.
Pinyon-juniper woodlands are of significant economic value for spring-fall livestock grazing and big game winter range. This has led to vegetation manipulations to improve these values. Fire is a natural disturbance, and its frequency and timing are major factors in vegetation dynamics. Precipitation is often inadequate for high plant cover, but is often of sufficient intensity to produce localized runoff and erosion. Plant composition and structure is extremely important for preserving soil resources because of its basis for all other values.
The hydrology ofthese watersheds is a function ofprecipitation amount, intensity and seasonality, the geology as it relates to topography, subsurface porosity, and surface soils and understory-overstory vegetation dynamics. When trees
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are dominant, there is a high transpiration component and high exposure of surface soils between trees that are major sources of runoff and erosion. Geologic parent materials are mainly sedimentary rocks such as limestones, dolomites, shales and sandstones, and igneous rocks. These woodlands are found on mesas, foothills, breaks, mesa edges, escarpments, and depositional areas. Soil surveys indicate that pinyon and juniper occur on almost all textural groups, and these woodlands are not necessarily limited by texture, stoniness, or depth.
It is difficult to characterize pinyon and juniper sites hydrologically because of the great variability in soils, geological substrate, slopes, and precipitation patterns. Studies have shown that evapotranspiration is the major process of water loss, and runoff is less than 10 percent of the water budget. This usually results in little water yield in the form of runoff or ground water recharge. -There are still many cases oflocalized runoff, erosion, down stream flooding, and deposition from pinyon-juniper dominated drainages. The combination of s ufficien t preci pitation (usually over 450 mm per year) and an impermeable layer can create a zone of saturation, and the resulting interflow may be sufficient to feed springs and streams.
Fire occurs in pinyon-juniper when there is sufficient understory to carry it from tree to tree, or when tree canopies
"close up" enough for fire to spread from crown to crown.
Evergreen pinyon and juniper trees have the ability to accumulate carbon slowly and efficiently by more active year-round photosynthesis than associated herbs and shrubs.
This, coupled with their tree growth form, allows the trees to build large above and below ground structures for capturing resources. Under these semiarid conditions, much of the limited precipitation is taken up by the tree's extensive root systems and transpired through their canopies. Tree-root exploitation of water and nutrients from the interspaces often results in the eventual purging of the understory plants in the absence of fire or other tree-killing disturbances.
Prior to European settlement, pinyon-juniper woodlands were open, sparse savannahs or were confined to rock, ridges, and shallow soils where fine fuels were too low to carry fires. The highest period of tree establishment beginning in the mid-1800's was downward in elevation and resulted in reduced understory fuels necessary to carry fires. The change in fire frequency came about initially with heavy understory grazing and removal of fine fuels in the late 1800's to early 1900's, and later with fire suppression following World War II.
Geologic substrate, soil, and climate interact to affect hydrologic responses and interactions. Parent materials produce soils with different infiltration, water-holding capacity, and fertility. Volcanic soils, with high fertility, support the most rapid invasion ofpinyon-juniper in the absence of fire. Interspace erosion associated with the loss of nutrients, mycorrhizal fungi, cryptogams, and water-holding capacity can result in permanent loss of understory potential. Such sites may remain as degraded woodlands with little diversity and high runoff potential. This erosion may also result in the loss of archeological values.
Pinyon and juniper woodlands have been subjected to a range of environmental and human-induced disturbances over the years. During the precontact period there were natural and Native American-induced fires and climatic fluctuations. After the mid-1800's came grazing, logging, and fire control. The loss of herbaceous forage and increases in woody vegetation led to the development of brush control and revegetation technologies applied to pinyon-juniper, sagebrush, and other rangelands. It is important to remember the site and situation-specific nature of responses to vegetation manipulations. Resource management is both a science and an art and requires experience and familiarity with specific conditions and responses to specific management.
Tree control projects are usually conducted to increase forage yield, to improve watershed conditions, to increase water yield, and to improve wildlife habitat. The most critical is to improve watershed conditions. Most control projects were conducted from the 1940's through the 1960's but dropped off in the 1970's.
The traditional view is that pinyon and juniper communities, especially on invasion sites, will degrade hydrologically and ecologically unless periodic fire or other tree reductions and associated natural revegetation or seeding allow for increased herbaceous and shrub cover. Proponents of this view are concerned that continuing fire control and lack of other tree control measures are threatening the soils and associated resources. The counter position is that maturing woodlands are not eroding and degrading, and land managers may be using unfounded hydrologic or other benefits to increase forage for livestock. Others may be using similar selective interpretations and self-serving speculations to prevent tree control practices. Proponents of both views seem to agree that grazing and site-specific conditions have affected hydrologic responses and that tree dominance can deplete understory vegetation and seed banks.
There are enough pinyon-juniper woodlands (about 30 million ha or 74 million acres) that we can be selective in vegetation management to improve wildlife habitat, increase forage for livestock, and benefit hydrologic processes.
The determination of which uses to provide and where to provide them must be based on the land's capabilities and human and wildlife preferences.
The capacity ofpinyon-juniper to dominate plant communities has been termed "super dominance" in reference to their ability to greatly oppress understory species and outlive the seed banks of these species. Successional stages of pinyon-juniper woodlands are not necessarily discreet, isolated stages but merely points along a continuum. The use ofthe term "stages" is used to facilitate communication. The following are stages often used to describe successional processes.
• Fire and Skeleton Woodland-In the first stage, live crown cover is reduced to or near zero, and the community looks totally devastated. If burning occurs before the closure of pinyon-juniper has purged the understory, the black surface persists only until sprouting species appear or seeds germinate from seed banks. If the understory has been purged and the site not seeded, the invasive species such as cheatgrass occupy the site.
162 USDA Forest Service Proceedings RMRS-P-9. 1999

• Annual Stage-This stage may be skipped if the burn occurred before the understory had been purged. Rapid crown cover of annuals is greatly facilitated by cheatgrass. This annual stage can be perpetuated by frequent fires that are fueled by cheatgrass. This stage can persist for 20 years and on southerly exposures up to 80 years.
• Perennial GrassIForb-This community can follow directly after fire if the perennial understory had not been purged by pinyon-juniper closure. Seeding has been successful in establishing good ground cover within
5 years postfire where understory has been purged.
Without seeding, cheatgrass can delay dominance of this community for 20 or more years.
• Shrub/Grass-This community can also follow immediately after a burn where sprouting shrubs and herbaceous species had not been purged. Where pinyonjuniper crown cover has been as high as 60 percent prior to burning, the shrub cover is often less that 2 percent
10 years postfire. In the absence of sprouting shrubs, crown cover may reach 20 percent or more in about 30 years postfire. This stage persists for about 50 years.
• Shrub/Open Tree-In this stage, crown cover of pinyon-juniper increases to about 20 percent. There is often a linear decrease in understory cover at about 5 to 20 percent pinyon-juniper crown cover. A prominent feature of this stage is the dense tree limbs extending to the ground level. Trees of various ages contribute to structural diversity, and this stage appears to be the most complex or diverse structural canopy in the sere. Ground cover is high for soil and watershed protection, and this stage is common for about 60 to 100 years postfire.
• Tree/Shrub Stage-This stage is sometimes not distinguished from the previous stages. Tree cover increases from 20 to 40 percent with a pronounced decrease in shrubs and herbaceous species. Understory species of previous stages begin to be purged. This stage is common for 100 to 200 years postfire.
• Mature Pinyon-Juniper-At this stage, tree crown cover is typically greater than 40 percent. The crowns are larger and more open than in previous stages, and lower branches are pruned off over time. Shrub and herbaceous layers are complete1Y purged by this time.
Cheatgrass remains at low levels, and its nearly ubiquitous distribution indicates that it will dominate the future early seres. Bare inters paces develop and persist in which rills and sheet erosion reach the highest levels except for the skeleton stage. This stage persists for about 200 years or until the next disturbance.
Capabilities are a function of climate, geology, soils, gradient, aspect, plant taxa, variability of sera I and plant communi ties, and other ecological features specific to the site. Values are a function of animal reaction to these features and the human perception and preference for points of a sere. Each seral stage is capable of supporting a different set of needs and desires. Each plant community has intrinsic value, and the value of each stage can vary widely within a diverse public.
Therefore, a mix of successional stages facilitates multiple use and a diversity of values. Higher resource values can be expected where the mix is taylored to the capabilities and values of specific ecological units within the landscape.
USDA Forest Service Proceedings RMRS-P-9. 1999 163