This file was created by scanning the printed publication. Errors identified by the software have been corrected; however, some errors may remain. Ecology and Management of Pinyon- Communities Within the Interior West: Overview of the "Resource Values Session" of the Symposium

James E. Bowns

Abstract-This paper summarizes 17 excellent, detailed papers texture, color, and fragrance. Markets still need to be devel­ presented during the section of the symposium on the resource oped for these products. values of the pinyon-juniper woodlands. James E. Bowns captures Cement board can be made with cement, wood fiber, and the salient points of each paper, a formidable task that required that water. It is fire resistant, relatively unaffected by water, and most of the detail be left out. The reader is encouraged to read the can be worked like particle board. complete papers for additional details. 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. Past, Present, and Potential Uses of Although some species ofjuniper have proven satisfactory Pinyon-Juniper for pulp, it produces low yields. Other problems are that the pulp is too difficult to bleach for white paper, too weak for Pinyon-juniper species are a sizable wood fiber resource unbleached high-grade bag and wrapping paper, and too for products that can be made from smaller, irregular stems soft for corrugating board. Economic feasibility for pulping and those that can capitalize on the unique physical and pinyon-juniper in the region is questionable. chemical characteristics of these species. Pinyon wood contains large quantities of oleoresin or gum. Firewood obtained from pinyon andjuniper has been used Products obtained from the include spirit, linseed oil, longer and more extensively than any other product. This is tung oil , ester gum, and zinc resinate. The Zuni still the main fuel in many rural areas as well as urban use Indians use the resin for an antiseptic, pottery glaze, and for in wood burning stoves and fireplaces. These species have burning in religious ceremonies. excellent fuel wood characteristics of heat content, ignition, Juniper woods contain large quantities of oily fragrant flaming, and fragrance. extractives rich in cedrol and associated essential oils. Other Juniper posts have historically been used because of their compounds should include terpene and sesquiterpene. J uni­ easy access and natural durability. A good post can last 60 per foliage also contains fragrant oily extractives. years, and the diameter ofthe heartwood is the determining Other important products include pine nuts and Christ­ criterion for durability. Juniper is also used for stub posts in mas trees. production is highly variable from area to power and telephone lines and highway guard rails. Young area and year to year, which ca uses problems for nut brokers and intermediate aged stands provide the best posts. Pinyon and processors. Pinyon trees are favored by many is not favored for posts because they are not of suitable form residents of the Interior West. The single needle pinyon is or durability. generally favored because it is more symmetrical. 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 Role of Pinyon-Juniper Woodlands causes excess saw wear and resin build up. in Aboriginal Societies Railroad ties and mine timbers are some of the usable products and are superior to those obtained from local Resources such as food, shelter, tool construction, tinder, softwoods. Furniture and novelty items (book ends, lamp and preferred settlement locations are available in the bases, clocks, jewelry boxes, and small chests) capitalize on pinyon-juniper woodlands. These woodlands provided ab­ the unique fragrance, color, and grain patterns of these original peoples some of the most basic raw materials for woods. sustaining life. Particle board can be made from both pinyon andjuniper. Juniper is somewhat better because of its specific gravity, Food Pine nuts were one ofthe most important foods of the early In: Monsen, Stephen B.; Stevens, Richard, comps. 1999. Proceedings: inhabitants ofthe Great Basin and Colorado Plateau. These ecology and management of pinyon-juniper communities within the Interior nuts were gathered in large quantities and were considered West; 1997 September 15-18; Provo, UT. Proc. RMRS-P-9. Ogden, UT: U.S. the single most important food species where they occurred. Department of Agriculture, Forest Service, Rocky Mountain Research Station. The nuts are high in both protein and fats, the proportions James E. Bowns is Range Ecologist, Southern Utah University, Cedar City, UT 84720.

USDA Forest Service Proceedings RMRS-P-9. 1999 157 varying among species. The fat content exceeds that of choco­ ranked second in percentage of obligate and semiobligate late and contains all 20 essential amino acids. Nuts provide species, third in total number of individuals counted, and tryptophan, which is deficient in diets of corn farmers. fourth in species richness and diversity. Only riparian areas Nut production varies from year to year, area to area, and had a higher percentage of obligate or semi obligate species. age of the tree stand. Pinus monophylla is more productive Of seven upland forest habitats studied, pinyon-juniper and predictable than P. edulis. A casual relationship has been ranked second in total individual birds and third in species proposed between the unpredictability of pinyon pine nuts richness and diversity. In general, the number ofspecies and with the high residential mobility of the Great Basin people. individuals tended to decrease with increasing elevation. Nuts were harvested in the early fall at about the time of Consideration of more than simply the number of species the first frost and eaten raw or toasted, hulled, winnowed, is important because an area that supports· a few rare and ground into paste for making a soup or gruel. species can be as important as one that supports many Soup was sometimes mixed with meat to add flavor and common species. Navajos made nut butter, which was spread on corn cakes. Studies show that chaining can negatively affect the Nuts were stored in pits or other storage facilities that abundance of cavity nesters, timber gleaners, aerial forag­ were lined with rocks, grass, or juniper bark and covered ers, and species that forage in or next to the foliage. Birds with bark, branches, dirt, and more rocks. This kind of that nest or forage on the ground use both treated and storage ensured that the nuts would tast at least all winter. untreated areas. Woodland treatments are not necessarily Juniper "" were occasionally used for food. bad for birds, and creating a mosaic of seral stages provides ate them fresh or pounded them for bread or juniper tea. the best balance of habitat features sought by birds. Shrub­ Utes ate the pulp fresh or dried, or used them as an ingredi­ dependent and edge-associated species benefit from well­ ent in bread or stews. Great Basin people used juniper designed treatments. Sites with high edge-to-interior ratios "berries" sparingly, but they were occasionally eaten in the should be selected, and more trees should be left standing fall and winter after they were boiled. near the edge. This will add structural complexity and thus compensate for the loss of overstory. Managers should also consider habitat values of mature Medicinal Uses woodlands when meeting watershed and forage production The use of pinyon as medicine was limited, but the objectives. The best option appears to be a landscape de­ and gum were boiled in water and drunk to purge worms and signed to include functional patches of all seral stages. other parasites. Juniper leaves were used in teas for the In another study, 53 bird species, using pinyon-juniper treatment of colds and coughs. woodlands for breeding, were observed on seven pinyon­ juniper sites. Only two species, blue-gray gnatcatcher and black-throated gray warbler, occurred on all seven sites, and Construction and Other Uses 77 percent were neotropical migrants. Researchers conclude that pinyon-juniper forests are important for the continued Pinyon and juniper were used for house construction, breeding success ofthese two species and the gray flycatcher. hogans, sweathouses, ramadas, fences, corrals, drying racks, Pinyon-juniper forests provide important food, cover, and and storage facilities. These trees were also used for fire nesting habitat for at least nine neotropical migrants, and material or kindling wood. the pinyon-juniper type supports a greater variety of birds J uni per bark was an integral element in roof construction, than had been anticipated. However, the total number of fiber for mats, diapers, menstrual pads, and cushioning and species depending entirely on this type for breeding is low protective lining for storage pits. compared to other habitat types. Pitch was used to line basketry water jugs as a sealant, as Sagegrouse depend upon sagebrush steppe throughout glue for ceramic vessels, and as a for attaching their distribution. The lack of fine fuels and more mineral projectile points or stone tools. soil has generally decreased fire frequency, although inten­ sity has increased in some areas. Sagegrouse populations have declined in much of their Wildlife former range, and these declines are most notable where Habitat values ofpinyon-juniper woodlands often receive habitat limitations including loss, fragmentation, and deg­ little consideration because they appear so extensive that radation of sagebrush ecosystems have occurred. there seems little possibility of exhausting the supply, and Some sites have been treated with the brush beating of the aridity and lack of vegetation diversity seems inconsis­ short (less than 1 m) pinyon and juniper trees, sagebrush, tent with highly productive wildlife habitat. Also, land and associated deciduous shrubs. Taller trees were cut with managers may consider mature pinyon-juniper undesirable chain saws, and some hand cutting removed trees from lek or at least less desirable than earlier seral stages because of sites. the lack of understory vegetation. These treatments doubled sagegrouse populations, and the increase was attributed to the decreased mortality of males during the breeding season and improved survival of Birds both males and females. Prior to the treatments raptors had hunted from the trees adjacent to the lek sites, and all These woodlands support rich and distinctive bird com­ documented sagegrouse mortality was attributed to preda­ munities and make substantial contributions to landscape­ tion by raptors. However, the effect of cutting trees was level avian diversity. In northeastern Utah pinyon-juniper confounded because sagebrush beating also occurred at the

158 USDA Forest Service Proceedings RMRS-P-9. 1999 lek sites, which increased the ability of the sage grouse to Mature Utah juniper "berries" are the most commonly detect predators at greater distances. Pinyon and juniper taken food by gray fox in terms of percent relative frequency trees were avoided from June through August, at which time of occurrence and mean percent ofvolume in scats. Chemical sagegrouse selected treated areas that had an abundance of analysis of juniper "" hulls indicates that they provide succulent forbs. the basic supply of nutrients and minerals. Mature juniper I t seems remarkable that sagegrouse populations respond "berries" are low in moisture, which concentrates more so quickly to treatments designed to solve an immediate energy and nutritional content into the hulls, therefore local problem. Outside of predation, mortality of this popu­ providing more value per unit weight than immature berries lation appeared low and no hunting was allowed. It appears with high moisture content. The hulls alone provide the that tree removal can increase usable habitat size by at least minimum gross energy needed for gray fox maintenance and 100 percent. then some. There may also be some zoopharmacological benefits of secondary compounds in purging external para­ site loads. Mammals Mammalian prey, mostly rodents and leporids, represent Small mammals are affected by juniper encroachment, the majority of the diet not consisting of juniper "berries." conversion, and subsequent impact§) of community struc­ The addition ofthe mammalian prey likely supplements any tural change. An estimated 341 animal species are found in nutritional deficiencies. the southeastern Oregon juniper steppe. Gray fox contribute to community, structure, dynamics, The number of captures is usually higher on cut sites. and function of Utah juniper dominated ecosystems. Gray Captures are higher on shrub sites than old-growth wood­ fox are efficient foragers that specialize in an interesting mix lands, and the structure provided by robust understory of vegetal and animal matter. The gray fox is the only vegetation and overhanging juniper skeletons provides su­ mammal known to forage extensively on the hulls ofjuniper perior security and forage in the cut and dropped sites. "berries." The hulls comprised a large part of their diets Leaving blocks of unchained vegetation should maintain during all seasons studied. woodland-dependent species while providing increased to­ Mature juniper "berries" exist in large quantities and pro­ tal numbers of small mammals in treated areas. Total vide a large volume of readily available nutrition through­ captures and number of species are higher in cut sites than out the year. "Berries" ripen on the tree and persist for up in uncut sites. This concurs with other studies that show to 2 years. Gray fox are adept at climbing trees and use that small openings can benefit a variety of wildlife. for a food source, resting, and escape cover. Cut sites have preferred structure, which is provided by Juniper pass through the digestive system intact, ~ncreased vigor (cover and height) of herbaceous species, and the metabolic residue in the scat provides the seeds with Increased production on cut sites, greater species rich­ a natural mulch of nitrogen and other minerals. This possi­ ness, and juniper slash. Cut sites generally provide in­ bly provides a valuable benefit to juniper community dy­ creased security and forage for small mammals. namics in the form of seed dispersal. An alternative view Opening stands of western juniper and leaving trees or may be that this seed dispersal is detrimental because it thinnings does not substantially affect small mammals. The increases the spread of juniper that may be interpreted as Great Basin pocket mouse appears to be the most sensitive undesirable. species to the loss of shrubs during the latter seral stages. Apparently gray fox do not actively feed on pinyon pine Some species such as wood rats are favored by trees. For nuts and acorns, which would require the breakdown of the maximum structural diversity shrub steppe communities shell or husk before they could obtain any nutritional benefit. should be managed through early-to-mid-seral woodlands. Rocky Mountain Bighorn sheep show a high preference for In late and closed woodlands, structural complexity and burned areas within pinyon-juniper and ponderosa pine plant diversity results in shifts in small mammal population communities, especially those burns located within or adja­ dynamics. cent to steep, rocky habitat within core use areas. This Fuel wood harvesting results in immediate, drastic, and positive response occurs in small or large burns. abrupt habitat changes. Small mammals have intricate Bighorn sheep generally avoid areas with a high density roles in ecosystem function, so they are a key component of of live or standing dead trees, which reduce visibility to pinyon-juniper woodlands. intolerable levels. In addition to high visibility, bighorns Slash left on the ground results in an increase of some prefer older burns dominated by grass, which constitutes rodent population regardless of overs tory condition. This 79 percent oftheir diet. Early seral stages are more valuable also affects microsite nutrient cycling, understory produc­ to bighorns than tree dominated areas. Therefore, mainte­ tion, and regeneration of overstory species. nance of bighorn habitat is highly dependent on repeated Overstory removal and slash accumulation seems to have burning or bighorn densities will be low. more beneficial effects for deer mice specifically and other species as well. However, these two effects were detrimental Amphibians and Reptiles to the pinyon mouse. Overstory is important to pinyon mice, and burning is of further detriment to this species. The distribution, abundance, and habitat affinities of am­ Burning of slash is considered detrimental and may offset phibians and reptiles have been documented in pinyon­ the beneficial effects of the slash. Small mammal populations juniper woodlands. Four species of amphibians and 26 spe­ are related to overstory adjustments or slash composition. cies 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 erosion. This condition predates the advent of Europeans distribution of most snakes is still poorly understood. Seven and their livestock by thousands of years. species of reptiles extended into the bristlecone-limber pine Most potential conflicts can be resolved where there are zone. well-documented inventories and an understanding of the Toads, frogs, skinks, and salamanders are found near habitat requirements and biology of narrow endemics. 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 Old-Growth Pinyon and Juniper specific research and management needs, have been Woodlands ______documented. Old-growth pinyon-juniper woodlands do not fit the typi­ cal image of old-growth coniferous forests. However, some of Endemic and Endangered the oldest stands throughout the Intermountain West are Plants low statured, open, semiarid woodlands. Old woodlands usually differ in structure and function Nearly all plants of Utah and other Western States that from postsettlement woodlands, thus adding diversity at the are listed as threatened, endangered, or sensitive are nar­ community and landscape levels. Concern over the rapid row endemics, which are defined as plants restricted to one expansion of these woodlands during the 20th century has or a few counties in one or perhaps two States. overshadowed the presence and values of presettlement Within the pinyon-juniper thermal belt plant generalists woodlands. In addition, wildlife studies have generally not are found on nearly all geologic strata and soil types, but separated postsettlement from pre settlement stands. pinyon-juniper and desert shrub communities also support Pinyon-juniper woodlands should be defined on the basis most of the narrow endemics in Utah. of tree age and stand structure and function. One age Edaphic control of vegetation by geologic formations is separation may be on the basis oftree establishment prior to greatest where geologic strata are exposed, and the area European settlement. In the Great Basin rapid expansion of must be xeric in order for the substates to be controlling. these woodlands coincided with settlement in the late 1860's Dessication is apparently necessary for the ultimate expres­ and 1870's. Old growth can also be based on the structural sion of edaphic control, and this is not as common at higher characteristics of the trees. With age, canopy morphology precipitations. Water tends to override the influence of shifts from a cone shaped to a rounded top. As trees age they geology. Xeric conditions are also associated with steep may exhibit broad asymmetrical tops, deeply furrowed bark, slopes, clifffaces, and wind swept slopes where plant special­ twisted trunks or branches, dead branches and spiked tops, ists are protected from the competition of generalists. Rela­ large lower limbs, narrow strips of bark, hollow trunks, large tively few narrow endemics are found where the area is well diameter to height ratios, and bright yellow lichens on the mantled with vegetation. Therefore, Utah, with much ex­ branches. Western and Utah juniper ages can exceed 1,000 posed geology and xeric conditions, supports numerous, years and pinyon 600 years. relatively narrow endemic plants. At the community level, old-growth woodlands should be Specific taxa have been arranged into three categories of described on the basis of the presence of old trees and apparent relationships to pinyon-juniper. Each taxon is structural characteristics such as standing and down dead, named, the geology and soils !1re discussed, and notes are decadent living trees, cavities,and lichen-covered branches. made on each species. These categories are (1) obligatory or The pinyon-juniper type has been described as climax with semiobligatory to pinyon-juniper, (2) apparent associates woodlands shifting to grasslands or shrub steppe only fol­ mostly in the interspaces of trees and exposed geologic lowing a disturbance such as fire. In the absence of a substrates, and (3) incidentals, which are found within the disturbance, these communities will eventually return to pinyon -j uni per but extend below into the sal t desert shrub or woodland. Old-growth woodlands occur over a wide range of above the pinyon-juniper on wind swept slopes and ridges. parent materials, soils, aspect, slope, elevation, climate, and Apparently, narrow Utah endemics have evolved where disturbance regimes. geology and erosion are the primary drivers of plant commu­ Ecological provinces may provide a first separation in the nity composition or dynamics, and these plants are unable to classification of old-growth woodlands. A current system compete with generalists on well-developed soils. Narrow considers: (1) community type based on ecological province, endemic plant population densities are often low, and sur­ land form, dominant shrubs and grasses, soils, and topogra­ vival is more a function of adaptation to harsh substrates phy; (2) tree age composition and structure; and (3) under­ and dry conditions than their ability to compete. story composition. Age classes are subdivided under Semibarren habitats, which have low potential for vegeta­ presettlement and postsettlement categories. tion manipulation, are occupied by these narrow endemics, Researchers have described 13 old-growth woodland types and these species can be used as indicators of these low of prehistoric and presettlement distribution and changes, potential sites. Sites better suited for the high production of extent and proportion of old growth, soils, species composi­ shrubs and herbaceous species are unsuitable for narrow tion, wildlife values, and other attributes. endemics. What should old-growth stands be managed for? These The strong relationship between highly erosive, geologic old-growth woodlands make up only a small percentage of strata, and narrow endemics indicates an evolutionary situ­ pinyon-juniper woodlands, and they are structurally and topo­ ation dependent on harsh conditions and high rates of graphically more complex than the younger, more abundant

160 USDA Forest Service Proceedings RMRS-P-9. 1999 woodlands. Old-growth is esthetically pleasing and provides plant diversity, and structure and provide quality habitat recreational, cultural, and spiritual opportunities. for wildlife and livestock. Fire policies influencing these old stands should be evalu­ Chaining and seeding, wildfires, and prescribed burning ated for both suppression and let burn. Fuelwood cutting has have resulted in numerous seeps, wet meadows, and peren­ been considered wasteful unless cutting is designed to re­ nial springs emerging. Previously dry stream channels are move postsettlement trees and restore presettlement stand developing into riparian areas. However, some negative structure. effects are slope instability and seepage erosion. Studies are needed to determine and describe the range of The hypothesis proposed for this phenomenon is that most old-growth woodlands. It is also important to evaluate springs occur at points of subsurface flow concentration presettlement and postsettlement changes in community where a shallow soils mantle exists over low permeability structure and composition, define desired future conditions, bedrock such as shale or where water may flow through a and develop management plans for restoring or maintaining confined aquifer of fractured bedrock or bedrock containing old-growth woodlands. These old stands are an important solution cavities. Flow might also be controlled by structural landscape component that support many plant and animal features such as faults. species, and interact with adjacent community types. Preliminary results suggest that most subsurface flow is through fractured bedrock that might create discrete pack­ ets of infiltration, transfer, and discharge. Unique geology of Pinyon and Juniper a site may force ground water to the surface, allowing Watersheds increases in water yield to be readily exploitable.

Erosion and Deposition Watershed Scale Research When juniper canopies begin to mature and close, New research is being developed to address the problems microtopographic elements become more pronounced. Cop­ encountered when dealing with extremely variable site pice dunes or mounds beneath the trees are evident. These conditions and protracted time scales. dunes are higher under the trees than in the interspaces. The specific objectives are to (1) establish a long-term Within the interspaces, the soil surface can be as much as watershed-scale research site on semi-desert and upland 1 m lower than at the trunk and are usually covered with climate zones and (2) perform mechanistic research in pin­ gravel. Under the trees the soils are relatively fine-textured yon-juniper woodlands that will study ecosystem dynamics and incorporated with leaf litter. The dunes or coppices such as energy flow, water and nutrient cycling, organismal absorb the energy of flowing water and restrict the sediment structure and function, and sediment source/sink relation­ delivery downslope. ships. At the same time, the project will address the more One question is ifsites dominated by maturejuniper trees pragmatic concerns associated with management objec­ represent degraded or degrading systems. One postulation tives, the effects of drastic disturbances and the results of that juniper successional trajectories are currently in place custodial management. and are likely to continue for centuries due to the longevity The design utilizes small watersheds and spatial nesting of these trees, resulting in a self-destructing system. There­ of tributary basins and provides integration of spatial and fore, it is necessary to identify sediment source and sink temporal variability on a realistic scale. Potential treat­ relationships, which will help identify the need for custodial ments will include (1) mosaic thinning, (2) simulated wild­ or active management. fire, (3) mechanical manipulation (chaining), and (4) an Soil under the trees has an organic horizon that is absent untreated control for evaluating carbon sequestration, in the interspaces. A petrocalcic horizon appears to restrict seed dispersal and population dynamics, and social the downward growth of and impede water percolation considerations. and vertical nutrient flux. This horizon is deeper under the coppice dune and nearer the surface in the sparsely veg­ etatedinterspace. The sagebrush fluve has a weakpetrocalcic Watershed Values and Conditions layer. Preliminary findings suggest that horizonation is differ­ Pinyon-juniper woodlands are of significant economic ent between coppice dunes, interspaces, and sagebrush value for spring-fall livestock grazing and big winter fluves, which might influence the distribution of vegetation. range. This has led to vegetation manipulations to improve Further studies of this problem are ongoing. these values. Fire is a natural disturbance, and its frequency and timing are major factors in vegetation dynamics. Pre­ cipitation is often inadequate for high plant cover, but is Hydrology and Spring Occurrence often of sufficient intensity to produce localized runoff and erosion. Plant composition and structure is extremely im­ Removal of junipers has altered the hydrologic regime of portant for preserving soil resources because of its basis for several small watersheds, resulting in large increases in all other values. springs and water yields. A Coordinated Resource Manage­ The hydrology ofthese watersheds is a function ofprecipi­ ment Plan was developed for the purpose of increasing and tation amount, intensity and seasonality, the geology as it maintaining the availability and duration of surface flows, relates to topography, subsurface porosity, and surface soils enhance ground water recharge, increase and maintain and understory-overstory vegetation dynamics. When trees

USDA Forest Service Proceedings RMRS-P-9. 1999 161 are dominant, there is a high transpiration component and natural and Native American-induced fires and climatic high exposure of surface soils between trees that are major fluctuations. After the mid-1800's came grazing, logging, sources of runoff and erosion. Geologic parent materials are and fire control. The loss of herbaceous forage and increases mainly sedimentary rocks such as limestones, dolomites, in woody vegetation led to the development of brush control shales and sandstones, and igneous rocks. These woodlands and revegetation technologies applied to pinyon-juniper, are found on mesas, foothills, breaks, mesa edges, escarp­ sagebrush, and other rangelands. It is important to remem­ ments, and depositional areas. Soil surveys indicate that ber the site and situation-specific nature of responses to pinyon and juniper occur on almost all textural groups, and vegetation manipulations. Resource management is both a these woodlands are not necessarily limited by texture, science and an art and requires experience and familiarity stoniness, or depth. with specific conditions and responses to specific management. It is difficult to characterize pinyon and juniper sites Tree control projects are usually conducted to increase hydrologically because of the great variability in soils, geo­ forage yield, to improve watershed conditions, to increase logical substrate, slopes, and precipitation patterns. Studies water yield, and to improve wildlife habitat. The most have shown that evapotranspiration is the major process of critical is to improve watershed conditions. Most control water loss, and runoff is less than 10 percent of the water projects were conducted from the 1940's through the 1960's budget. This usually results in little water yield in the form but dropped off in the 1970's. of runoff or ground water recharge. -There are still many The traditional view is that pinyon and juniper communi­ cases oflocalized runoff, erosion, down stream flooding, and ties, especially on invasion sites, will degrade hydrologically deposition from pinyon-juniper dominated drainages. The and ecologically unless periodic fire or other tree reductions combination of s ufficien t preci pitation (usually over 450 mm and associated natural revegetation or seeding allow for per year) and an impermeable layer can create a zone of increased herbaceous and shrub cover. Proponents of this saturation, and the resulting interflow may be sufficient to view are concerned that continuing fire control and lack of feed springs and streams. other tree control measures are threatening the soils and Fire occurs in pinyon-juniper when there is sufficient associated resources. The counter position is that maturing understory to carry it from tree to tree, or when tree canopies woodlands are not eroding and degrading, and land manag­ "close up" enough for fire to spread from crown to crown. ers may be using unfounded hydrologic or other benefits to Evergreen pinyon and juniper trees have the ability to increase forage for livestock. Others may be using similar accumulate carbon slowly and efficiently by more active selective interpretations and self-serving speculations to year-round photosynthesis than associated and shrubs. prevent tree control practices. Proponents of both views This, coupled with their tree growth form, allows the trees to seem to agree that grazing and site-specific conditions have build large above and below ground structures for capturing affected hydrologic responses and that tree dominance can resources. Under these semiarid conditions, much of the deplete understory vegetation and seed banks. limited precipitation is taken up by the tree's extensive There are enough pinyon-juniper woodlands (about 30 systems and transpired through their canopies. Tree-root million ha or 74 million acres) that we can be selective in exploitation of water and nutrients from the interspaces vegetation management to improve wildlife habitat, in­ often results in the eventual purging of the understory crease forage for livestock, and benefit hydrologic processes. 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, Multiple Use Management Based on ridges, and shallow soils where fine fuels were too low to Diversity and Capabilities carry fires. The highest period of tree establishment begin­ ning in the mid-1800's was downward in elevation and The determination of which uses to provide and where to resulted in reduced understory fuels necessary to carry provide them must be based on the land's capabilities and fires. The change in fire frequency came about initially with human and wildlife preferences. heavy understory grazing and removal of fine fuels in the The capacity ofpinyon-juniper to dominate plant commu­ late 1800's to early 1900's, and later with fire suppression nities has been termed "super dominance" in reference to following World War II. their ability to greatly oppress understory species and out­ Geologic substrate, soil, and climate interact to affect live the seed banks of these species. Successional stages of hydrologic responses and interactions. Parent materials pinyon-juniper woodlands are not necessarily discreet, iso­ produce soils with different infiltration, water-holding ca­ lated stages but merely points along a continuum. The use pacity, and fertility. Volcanic soils, with high fertility, sup­ ofthe term "stages" is used to facilitate communication. The port the most rapid invasion ofpinyon-juniper in the absence following are stages often used to describe successional of fire. Interspace erosion associated with the loss of nutri­ processes. ents, mycorrhizal fungi, cryptogams, and water-holding • Fire and Skeleton Woodland-In the first stage, live capacity can result in permanent loss of understory poten­ crown cover is reduced to or near zero, and the commu­ tial. Such sites may remain as degraded woodlands with nity looks totally devastated. If burning occurs before little diversity and high runoff potential. This erosion may the closure of pinyon-juniper has purged the under­ also result in the loss of archeological values. story, the black surface persists only until sprouting Pinyon and juniper woodlands have been subjected to a species appear or seeds germinate from seed banks. If range of environmental and human-induced disturbances the understory has been purged and the site not seeded, over the years. During the precontact period there were 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 • Tree/Shrub Stage-This stage is sometimes not dis­ occurred before the understory had been purged. Rapid tinguished from the previous stages. Tree cover in­ crown cover of annuals is greatly facilitated by cheat­ creases from 20 to 40 percent with a pronounced de­ grass. This annual stage can be perpetuated by frequent crease in shrubs and herbaceous species. Understory fires that are fueled by cheatgrass. This stage can species of previous stages begin to be purged. This stage persist for 20 years and on southerly exposures up to 80 is common for 100 to 200 years postfire. years. • Mature Pinyon-Juniper-At this stage, tree crown • Perennial GrassIForb-This community can follow cover is typically greater than 40 percent. The crowns directly after fire if the perennial understory had not are larger and more open than in previous stages, and been purged by pinyon-juniper closure. Seeding has lower branches are pruned off over time. Shrub and been successful in establishing good ground cover within herbaceous layers are complete1Y purged by this time. 5 years postfire where understory has been purged. Cheatgrass remains at low levels, and its nearly ubiqui­ Without seeding, cheatgrass can delay dominance of tous distribution indicates that it will dominate the this community for 20 or more years. future early seres. Bare inters paces develop and persist • Shrub/Grass-This community can also follow imme­ in which rills and sheet erosion reach the highest levels diately after a burn where sprouting shrubs and herba­ except for the skeleton stage. This stage persists for ceous species had not been purged. Where pinyon­ about 200 years or until the next disturbance. juniper 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, Capabilities and Values crown cover may reach 20 percent or more in about 30 Capabilities are a function of climate, geology, soils, gradi­ years postfire. This stage persists for about 50 years. ent, aspect, plant taxa, variability of seraI and plant commu­ • Shrub/Open Tree-In this stage, crown cover of pin­ ni ties, and other ecological features specific to the site. Values yon-juniper increases to about 20 percent. There is often are a function of animal reaction to these features and the a linear decrease in understory cover at about 5 to 20 human perception and preference for points of a sere. Each percent pinyon-juniper crown cover. A prominent fea­ seral stage is capable ofsupporting a different set ofneeds and ture of this stage is the dense tree limbs extending to the desires. Each plant community has intrinsic value, and the ground level. Trees of various ages contribute to struc­ value of each stage can vary widely within a diverse public. tural diversity, and this stage appears to be the most Therefore, a mix of successional stages facilitates multiple complex or diverse structural canopy in the sere. Ground use and a diversity of values. Higher resource values can be cover is high for soil and watershed protection, and this expected where the mix is taylored to the capabilities and stage is common for about 60 to 100 years postfire. values of specific ecological units within the landscape.

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