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A greenhouse study was conducted to determine the effects of litter leachate and litter depth of Utah juniper [Juniperus osteosperma (Torr.) Little] on seedling emergence and emergence rate of 8 common herbaceous understory species. Species tested were: ?Secar' bluebunch wheatgrass [Pseudoroegnaria spicata (Pursh) A. Love], bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey], cheatgrass (Bromus tectorum L.), ?Paiute' orchardgrass (Dactylis glomerata L.), ?Appar' Lewis flax (Linum lewisii Pursh), ?Delar' small burnet (Sanguisorba minor Scop.), antelope bitterbrush [Purhsia tridentata (Pursh) DC.], and mountain big sagebrush [Artemisia tridentata spp. vaseyana (Rydb.) J. Boivin]. Three water treatments (distilled water, 1%, and 10% litter leachates) and 3 litter depths (0, 3, and 5 cm) were tested. Leachates decreased seedling emergence of orchardgrass and small burnet. Emergence rate was unaffected by leachate treatments. Seedling emergence of all species tested decreased significantly with increasing litter depth. Emergence rate was initially slower in pots with litter, but after 2 weeks no differences were found. DOI:10.2458/azu_jrm_v56i1_horman

In the northwest Great Basin, western juniper (Juniperus occidentalis subsp. occidentalis Hook.) is encroaching into aspen (Populus tremuloides Michx.) communities. There is a concern that aspen communities in this region are in a state of decline, but their status has not been documented. This study determined the timing, extent, and some of the effects of this expansion. Ninety-one aspen stands were sampled for density, canopy cover, age, stand structure, and recruitment of western juniper and aspen. Soils and tree litter beneath aspen and western juniper were collected to analyze the effects of western juniper on soils. Additionally, 2 large aspen complexes in southeast Oregon were intensively aged to determine disturbance (fire) frequencies. Western juniper encroachment peaked between 1900 and 1939 with 77% of all juniper trees sampled having been established during this period. Three-fourths of aspen stands sampled have established populations of western juniper. Twelve percent of aspen stands sampled were completely replaced by western juniper and another 23% dominated by western juniper. Average density of western juniper in aspen sites was 1,573 trees ha(-1). Seventy percent of aspen stands sampled had zero recruitment of new aspen. Aspen stands averaged 98 years old. There was an inverse correlation between aspen canopy cover and western juniper canopy cover. Soils influenced by western juniper had a higher C:N ratio, pH, salts, lime, and sulfate, and lower amounts of magnesium, iron, copper, and manganese. Aspen litter had a lower C:N ratio than western juniper litter. Two major aspen complexes sampled had even-age, 2-tiered even-age, and multiple-age aspen trees. The absence of presettlement juniper within all sampled aspen stands suggests fire was the primary stand-replacing disturbance in these northwest Great Basin aspen communities. The lack of fire coupled with aspen stand decadence and low recruitment levels will allow for the continued encroachment and replacement of aspen communities by western juniper in the northwest Great Basin. DOI:10.2458/azu_jrm_v54i6_wall

Excessive cover of juniper (Juniperus pinchotii Sudw.) reduces forage production, interferes with livestock management, and diminishes the watershed and wildlife habitat values of rangelands. We studied whether juniper seedlings were differentially suppressed in the presence of different grass species, and to what extent established mesquite (Prosopis glandulosa Torr.) trees facilitated or competed with establishing juniper seedlings. Seedlings growing with any of the grasses (RGR = 0.23 to 0.43 cm cm(-1)) grew significantly less than those with no grass competition (RGR = 0.72 cm cm(-1))(P 0.05), indicating that mesquite root competition with juniper is probably inconsequential. Since junipers grow mainly in fall, winter and spring when mesquite trees are dormant and leafless, the lack of competition may largely be due to these 2 species using resources at different times of the year. Greater nutrient availability beneath mesquite canopies, reduction of summer temperatures, and temporal separation of resource use clearly benefit juniper seedlings growing in the presence of mesquite. Managing for a vigorous grass component with low densities and cover of mesquite is the best way to limit the rate of invasion by juniper. DOI:10.2458/azu_jrm_v54i6_teague

While considerable attention has been given to the areal expansion of juniper (Juniperus sp.) in the western United States, the presence and ecological significance of old-growth juniper communities has gone largely unnoted. Increased recognition of these communities has prompted questions about how to recognize old-growth, community structure, ecological importance, and appropriate management. As an initial analysis of old-growth western juniper woodlands (Juniperus occidentalis Hook var. occidentalis Vasek) in central Oregon, this study investigated old-growth community structure on eolian-sand derived soils. These woodlands represent the most extensive old-growth western juniper woodlands throughout its range. Nine study plots were established at 7 sites. Within each plot, densities and physical attributes of all live trees and large standing and fallen woody detritus were recorded. Additional measurements for live trees included canopy cover, apparent age class (pre- or postsettlement), and a sampling of tree ages. Aging of trees older than 250 years was complicated by extensive heartwood rot. Shrub density and cover were measured by species. Understory cover was measured by species and functional type. Bare ground, rock, juniper litter, other litter, moss, and cryptogamic crust cover were also measured. Plant cover ranged from 11 to 33% for trees, 0 to 10% for shrubs, 3 to 12% for perennial grasses, 1 to 2% for forbs, and from 0 to 0.1% for annual grasses. The woodlands contained at least 80 trees ha(-1) aged over 200 years. Correlations between tree parameters and understory structure and composition were generally poor. Differences in plant composition among these stands was primarily attributed to elevation, slope, and percent sand content. Structural characteristics that distinguished old-growth stands from younger stands included tree growth form, presence of standing and dead large woody debris, lichen on dead branches, and a relatively open canopy. Results provide a preliminary basis for identifying old-growth Juniperus occidentalis stands, as a prelude to the development of management plans and further research into the functional characteristics of the systems. A definition of old-growth juniper woodlands is presented. DOI:10.2458/azu_jrm_v54i5_waichler

Knowledge of the rate woody plant canopy cover increases is essential for understanding the ecology of rangeland plant communities, determining the economic feasibility of brush management practices, and for scheduling initial and maintenance control practices. We determined rates of change in redberry juniper (Juniperus pinchotii Sudw.) canopy cover from the mid 1950s through the late 1990s at 5 locations in western Texas on rangeland that had been chained or grubbed for juniper control and on adjacent untreated areas. Juniper cover was estimated from aerial photographs by the line intercept method using a 10-X monocular lens with a vernier. Juniper cover increased at 0.35 +/- 0.06 percentage units year(-1) on untreated sites and at 1.01 +/- 0.07 percentage units year(-1) following chaining or grubbing. Juniper cover returned to pre-treatment levels in an average of 20 years (range 11 to 25) following chaining or grubbing. Herbage production on untreated rangeland was predicted to decline slowly (2.4 to 5.0 kg ha(-1) year(-1)) as juniper cover increased from 6 to 14% and rapidly (> 8 kg ha(-1) year(-1)) as juniper cover increased from 30 to 38%. Herbage production was predicted to decline at a constantly increasing rate following mechanical control of juniper, from < 2 kg ha(-1) year(-1) in year 1 to 23 kg ha(-1) year(-1) in year 29. Potential additional livestock carrying capacity due to juniper control would be under estimated by more than 40%, assuming forage production without treatment remained constant during the entire planning horizon of an economic analysis. To avoid significant reductions in livestock carrying capacity, redberry juniper control should be implemented before its canopy cover exceeds about 20%. DOI:10.2458/azu_jrm_v54i5_ueckert

Redberry juniper (Juniperus pinchotii Sudw.) is a noxious shrub or small tree that invades rangelands in northwest Texas. Field reflectance measurements showed that redberry juniper had lower visible and higher near-infrared (NIR) reflectance than associated species and mixtures of species in February. The low visible reflectance of redberry juniper was due to its darker green foliage than associated species, whereas its high NIR reflectance was attributed to its greater vegetative density than associated vegetation. Redberry juniper had a distinct reddish-brown image tonal response on color-infrared aerial photographs obtained in February. Computer analysis of a color-infrared photographic transparency showed that redberry juniper infestations could be quantified. An accuracy assessment performed on the classified image had a user's accuracy of 100% and a producer's accuracy of 94% for redberry juniper. DOI:10.2458/azu_jrm_v54i3_everitt

Goats consume juniper, but toxic terpenoids within the plant limit intake. Our objective was to determine if dosing goats with the adsorptive compound activated charcoal would increase juniper consumption. Twenty Boer-cross goats were placed in individual pens; at 0800 hours, 10 were dosed with 1 g kg(-1) body weight (BW) of activated charcoal in an aqueous solution, and 10 were not dosed. Dosing occurred daily for 10 days. Goats were offered redberry juniper (Juniperus pinchotii Sudw.) in Trial 1, ashe juniper (Juniperus ashei Buch.) in Trial 2, and a choice between redberry and ashe juniper in Trial 3. For each trial, juniper was offered to all goats for 2 hours after dosing with activated charcoal. In Trial 1, goats dosed with activated charcoal consumed more (P < 0.05) redberry juniper during the first 5 days of exposure. In Trial 2, activated charcoal did not affect ashe juniper intake. In Trial 3, dosing with activated charcoal did not affect juniper intake. All goats preferred ashe to redberry juniper. Juniper intake increased across days of exposure for Trials 1 and 2, apparently because goats adapted to the terpenoids in juniper through repeated exposure. It appears that activated charcoal will only increase redberry juniper intake during initial exposures. DOI:10.2458/azu_jrm_v54i3_bisson

In recent times, pinyon (Pinus spp.)-juniper (Juniperus spp.) woodlands have expanded into large portions of the Southwest historically occupied by grassland vegetation. From 1997‐1998, we studied responses of breeding birds to one-seed juniper ( J. monosperma) woodland expansion at 2 grassland study areas in northern Arizona. We sampled breeding birds in 3 successional stages along a grassland-woodland gradient: un-invaded grassland, grassland undergoing early stages of juniper establishment, and developing woodland. Species composition varied greatly among successional stages and was most different between endpoints of the gradient. Ground-nesting grassland species predominated in uninvaded grassland but declined dramatically as tree density increased. Tree- and cavity-nesting species increased with tree density and were most abundant in developing woodland. Restoration of juniper-invaded grasslands will benefit grasslandobligate birds and other wildlife.

Woody cover, when expressed at the scale of the 207 km2 Cusenbary Draw basin, remained unchanged (approximately 23%) from 1955 to 1990. When expressed at the scale of range sites, woody cover declined on sites with relatively high production potential and increased on sites with relatively low production potential. Change in woody cover distribution at sub-range site scales, increased low and high woody covers and decreased intermediate woody cover, would be expected to lead to increased water yield at the basin scale because there was an apparent threshold woody cover (approximately 20%) above which simulated evapotranspiration (ET) changed little with increasing woody cover. This potential increase, however, was more than offset by the decreased water yield due to increased ET loss associated with compositional changes of woody vegetation from oak to juniper. A set of woody cover-ET regression curves was developed for different range sites based on simulation studies using the SPUR-91 hydrologic model. Based on these woody cover-ET regression curves and GIS analysis, no brush management would result in a 35% decrease in water yield, while a hypothetical brush management cost-share program would increase water yield by 43% over the 1990 level. Benefits in water yield and forage production from brush management differ in different range sites. A brush management cost-share program that preferentially allocated brush management to sites with deep soil and the highest forage production potential increased water yield by 50%, compared to a 100% increase if brush management were preferentially allocated on sites with shallow soil and highest water yield potential. These model results illustrate that the spatial scale of assessment and spatial distribution of brush management among range sites should be important concerns associated with developing and evaluating brush management policies. DOI:10.2458/azu_jrm_v54i2_wu

Supplemental polyethylene glycol (PEG) increases intake of foods high in tannins, but it is not known if PEG affects preference when herbivores forage on a variety of foods that differ in concentrations of macronutrients and tannins. We investigated how macronutrients, tannins, and PEG affected preferences of goats (Caprus hircus) for current season's and older growth twigs from the shrub blackbrush (Coleogyne ramosissima Torr.). In blackbrush, current season's twigs are higher than older twigs in macronutrients, but goats prefer older twigs because high levels of tannins in current season's twigs decrease preference. We conducted a pen trial and a paddock trial. During the 7-day pen trial, goats were offered current season's twigs and older twigs throughout the day. Eight goats were supplemented with 20 g PEG mixed with 100 g ground alfalfa (Medicago sativa L.) pellets, and 8 goats were supplemented with 100 g ground alfalfa pellets. Goats supplemented with PEG ate more current season's twigs than goats that did not receive PEG (P = 0.04). During the 17-day paddock trial, 10 goats were supplemented with 50 g PEG mixed with ground alfalfa/barley (Hordeum vulgare L.), and 10 goats were supplemented with ground alfalfa/barley. Goats supplemented with PEG preferred current season's to older twigs, whereas PEG-unsupplemented goats preferred older to current season's twigs (P = 0.0001). Goats had equal preference for juniper (Juniperus osteosperma Torr.) trees (P = 0.243). Collectively, our findings show that supplemental PEG can change food preferences. DOI:10.2458/azu_jrm_v54i2_titus

Assessment of herbaceous standing crop in heterogeneous range plant communities requires large numbers of samples to account for inherent variability. The dry-weight-rank method (DWR) was developed to eliminate the need for clipping and sorting of herbage to determine relative proportions on a dry weight basis. The technique was assessed for applicability and accuracy in the mixed prairie of the Texas Rolling Plains. Much of the herbage within the communities investigated occurred in monospecific patches that resulted in only 15% of quadrats having 3 species ranked for which DWR was designed. Non-harvest methods of determining grass proportion by species were compared to harvested proportions in mesquite (Prosopis glandulosa Torr.) and redberry juniper (Juniperus pinchotii Sudw.) communities. Estimation methods evaluated were 1) harvest by species, 2) weight estimation by species, 3) DWR with quadrat weighting, 4) unweighted estimated proportion by species, and 5) unweighted DWR. Correlations of non-harvest to harvest proportions were improved with quadrat weighting. Weighting improved values more in the juniper than in the mesquite communities. Although cumulative ranking of DWR multipliers was necessary in 85% of sample quadrats, there was a high correlation (r2>0.995) between weight estimation and weighted DWR and between estimated proportion and unweighted DWR. This indicates that cumulative ranking with the original DWR multipliers was virtually the same as evaluator estimation. Analysis of variance indicated significant differences in non-harvest methods compared to harvesting. Quadrat weighting with DWR was necessary to draw the same statistical conclusions between means that harvest data provided. Ranks are easier to apply and more likely to be applied similarly by individual evaluators than estimated proportions. For sites with high standing crop variation and patchiness of species that require considerable use of cumulative ranking, DWR with quadrat weighting provides adequate determination of species proportions of biomass. DOI:10.2458/azu_jrm_v54i1_dowhower

Western juniper (Juniperus occidentalis Hook.) has been actively invading shrub steppe communities during the past 120 years. The majority of these stands are still in transition, from early open juniper shrub steppe communities to closed juniper woodlands. In addition, juniper expansion has been occurring across a broad array of soils and topographic positions. Despite the high degree of spatial and developmental heterogeneity, juniper woodlands are frequently treated generically in resource inventories, management, and wildlife habitat assessments. Our goal was to evaluate the impact of western juniper encroachment and dominance on plant community composition and structure across several plant associations. This study was conducted in southeastern Oregon and northeastern California on low sagebrush (Artemisia arbuscula Nutt.), mountain big sagebrush (A. tridentata spp. vaseyana (RYBD.)Beetle), and aspen (Populus tremuloides Michx.) alliances. Stages of woodland development across plant associations were categorized into 1 of 4 successional phases (early, mid, late, and closed) based on tree growth and stand structural characteristics. Plant cover by species group, species diversity and richness, bareground cover, soil characteristics, elevation, aspect, and slope were measured in 108, 60 x 46 m macroplots. Twinspan was used to sort plant communities. Regression analysis was used to evaluate the relationship of tree canopy cover to shrub and herbaceous cover. Herbaceous and bareground cover were compared between early and closed stands within plant communities. Woodland structure at stand closure was different among associations varying from 19% cover and 64 trees ha-' in a low sagebrush community to 90% cover and 1,731 trees ha-' in an aspen community. Increase in juniper dominance had little impact on low sagebrush and an inconsistent effect on bitterbrush (Purshia tridentata Pursh.). In the mountain big sagebrush alliance, sagebrush cover declined to approximately 80% of maximum potential as juniper increased to about 50% of maximum canopy cover. Aspen (Populus tremuloides Michx.) also declined as juniper dominance increased. Herbaceous cover and species diversity declined and bare ground increased with increasing juniper dominance in the mountain big sagebrush/Thurber needlegrass association. However, herbaceous cover on the deeper soils characterized by Idaho fescue did not decrease with increasing juniper dominance. To determine This research was supported by the Eastern Oregon Agricultural Research Center (EOARC), and Bureau of Land Management Districts Burns Ore, Lakeview Ore, and area office Alturas Calif, and Modoc National Forest. EOARC is jointly operated by Oregon State University and USDA Agricultural Research Service. The authors wish to thank Lee Eddleman, Robin Tausch, Roger Sheley, Bill Krueger, and 2 anonymous reviewers for their constructive comments. Oregon State Agricultural Experiment Station Technical Paper Number 11621 Manuscript accepted 6 Mar. 2000. the effect of juniper dominance or woodland management on community composition and structure, plant community and stage of stand development should be identified.

A fire scar chronology was constructed from ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and Rocky Mountain juniper (Juniperus scopulorum Sarg.) trees within the 70 km 2 R o c h e l l e Hills Area of the Thunder Basin National Grasslands, in north east Wyoming. A total of 65 fire scars occurred in 48 crossdated samples, and a master fire chronology was constructed for the period 1565 to 1988. No trees recorded more than 3 fires and most (26 of 42) recorded only one. For this reason, fire frequency intervals were considered as fire-free intervals in the Rochelle Hills Area. The Weibull Median Probability Interval (WMPI) for the entire period of record was 7.4; 7.9 for the non suppression period (1565 to 1939); and 6.7 for the suppression period (1940 to 1988). Infrequent occurrence of multiple scars, rough topography, and low potential substrates suggest that understory fuel loads were limited in amount and spatial consistency during most fire years. Position of scars within annual growth rings suggests that most fires (80%) occurred during the latter stages of the growing season or during the dormant period.

Wood from a shabti from the tomb of Sethos I has been examined and identified as a species of juniper.

Expansion of western juniper (Juniperus occidentalis spp. occidentalis Hook.) woodlands in the sagebrush steppe has the potential to change composition, structure, and productivity of understory vegetation. Cutting of western juniper woodland can potentially restore understory productivity and diversity. Understory responses were assessed after cutting a juniper woodland in southeastern Oregon in 1991. The experimental design was a randomized complete block with eight, 0.8 ha sized blocks and 2 treatments, cut and uncut woodland. Understory cover, density, diversity, biomass, and nitrogen (N) status were compared between treatments after cutting Plants were separated into S functional groups: bluegrass (Poa spp.), perennial bunchgrass, perennial forte, annual forte, and annual grass. Cutting of juniper reduced below ground interference for soil water and N. Leaf water potentials were less negative (p

Redberry juniper (Juniperus pinchotii Sudw.) is a common invasive brush species that reduces rangeland productivity over vast acreages in the Rolling Plains and Edwards Plateau regions of Texas. The objectives of this study were to evaluate the economic feasibility of redberry juniper control and determine the optimum treatment cycle for maintenance burning. A response equation was used to estimate the relationship between herbage production and redberry juniper canopy. Data to estimate the relationship was obtained for a site in the Texas Rolling Plains. The analysis used chaining as the initial treatment and periodic prescribed burns as maintenance treatments. Additional livestock production resulting from brush treatments and the costs of treatments were estimated and used to calculate net present values of the investment in brush control over a 30-year time horizon. Net present values indicated that juniper control was economically feasible across a wide range of economic and environmental conditions. Prescribed burn intervals were found to be optimal at 7-year intervals under most conditions.

The recent expansion of juniper into sagebrush steppe communities throughout the semiarid Intermountain West is most frequently attributed to the reduced role of fire, introduction and overstocking of domestic livestock in the late 1800s, and mild and wet climate conditions around the turn of the century. This hypothesis has, however, limited quantitative support. There are few studies of fire history in the sagebrush steppe and none that examine the chronosequence of changes in mean fire intervals, introduction of livestock, and coincident climatic conditions with the initiation of post-settlement juniper expansion. This study was undertaken to test the hypothesis that the postsettlement expansion of juniper was synchronous with the introduction of domestic livestock, reduction in fire frequency, and optimal climate conditions for plant growth. We documented the fire history and western juniper (Juniperus occidentalis Hook). woodland chronology for a sagebrush steppe in a 5,000 ha watershed in south central Oregon. Regional tree ring data were used as proxy data for presettlement climatic conditions. Western juniper age distribution was determined by coring trees across the study area. Fire history was constructed from several small clusters of presettlement ponderosa pine (Pinus ponderosa Laws.) scattered across the study area. Samples were crossdated to determine fire occurrence to the calendar year. Mean fire intervals were computed for each cluster based on cumulative fire history of each tree sampled within the cluster. Fire events in low sagebrush (Artemisia arbuscula Nutt.) were documented by determining death dates of fire-killed western juniper trees. Records dating the introduction and buildup of livestock during the late 1800s and dates of initial fire suppression were summarized. Western juniper expansion began between 1875 and 1885, with peak expansion rates occurring between 1905 and 1925. The fire record spans 1601 to 1996. Before 1897, mean fire intervals within individual clusters ranged from 12 to 15 years with years between fires varying between 3 to 28. Nearly one third of the fires in the basin were large and usually proceeded by one year of above-average tree ring growth. Two fire events were recorded in the sparsely vegetated low sagebrush site, 1717 and 1855. The last large fire occurred in the study area in 1870 and the last small fire in 1897. The time sequence of wet climatic conditions between 1870 and 1915, introduction of livestock, and the reduced role of fire support the hypothesis that these factors contributed to the postsettlement expansions of western juniper.

Timema coffmani sp. nov. is described from southwestern Arizona. It is a specialist feeder on juniper (Juniperus). Morphologically it is similar to T. ritensis Hebard from southeastern Arizona. The previously unknown female sex of T. ritensis also is described and both sexes are

We determined rates of western juniper (Juniperus occidentalis spp. occidentalis Hook.) density and cover change during the period 1951 to 1994 at 3 adjacent sites with nearly identical elevation, slope, aspect, soils, plant communities, and climate, but different land-use histories. The 3 sites are located in central Oregon at the confluence of the Deschutes and Crooked Rivers. Two of the sites are typical of central Oregon rangelands in that they have a history of anthropogenic disturbance including active fire suppression and domestic livestock grazing. The third site is a relict mesa that is a protected Research Natural Area and has experienced minimal anthropogenic impacts. We used large scale aerial photography to determine cover and density of western juniper in 1951, 1956, 1961, 1972, 1982, and 1994. We found that western juniper density and cover during the last 4 decades increased at all sites, with changes on the relict site similar to those on one of the disturbed sites. We suggest that even though 2 of the traditionally cited causes of western juniper expansion since the late 1800s (altered fire regimes, domestic livestock grazing) may have contributed to expansion on our disturbed sites, these mechanisms can not explain expansion on the near-relict mesa. Further, we examined climatic changes since 1900 in the region and concluded that the data did not fully support a climate-driven mechanism for the expansion. In seeking to explain western juniper expansion on semiarid rangelands, we suggest that all potential causal mechanisms (e.g., fire history, biological inertia, climate, domestic grazing, atmospheric CO2 enrichment) be considered.

We investigated fruit damage by insects as well as fruit abortion in relation to the mutualism between Juniperus communis, a fleshy-fruited plant dominant in the high mountains of southeastern Spain, and its bird disperser assemblage. For two years. we performed field experiments to analyse fruit selection by birds, offering birds different types of anomalous fruits (unripe, aborted, pulp-sucker infested and seed-predator attacked) and comparing the removal rate to that of ripe, healthy, control fruits. In addition, we studied the proportion of fruits attacked by the seed predator in samples of fruits which, after manipulation and rejection by birds, we found lying underneath plants. We compared these data to values in samples of fruits which we took directly from plants. Finally, over four years, the abundance of predispersaldepredated seeds in the seed rain dispersed by birds was compared with the abundance in seeds taken directly from plants. Fruit-choice experiments showed that unripe, aborted and fruits attacked by pest insects (both pulp sucker and seed predator) were strongly counterselected by these frugivorous birds. The proportion of fruits attacked by seed-predator in the sample of fruits manipulated and rejected was significantly higher than in the fruits taken from plants. For all study years, the proportion of depredated seeds was significantly lower in the sample of seeds dispersed by birds than in the sample of seeds taken from plants. Bird response to pests was not categorically to accept or reject fruit, but rather was influenced by pest density. Birds showed two different levels of fruit selection, depending on the type of fruit: visual discrimination, against fruits that are unripe, aborted and infested by the pulp sucker: and within-beak discrimination, against fruits attacked by the seed predator. In the study, both pests either died or left the fruit when ripe, and therefore frugivorous birds did not interfere directly with frugivorous insects. On the contrary, insects did interfere indirectly with birds, promoting the rejection of pest-attacked fruits by birds. Bird dispersers overcame the predispersal interference of pest fruit damage and fruit abortion and increased the proportion of healthy seeds in the seed rain. This fact, together with the great quantity of seeds dispersed by birds, reinforces the importance of birds as plant mutualists.

Angora mutton goats (Capra hircus) were fed diets of either live oak [Quercus virginiana (Small) Sarg. var. fusiformis], alfalfa hay (Medicago sativa L.), Coastal bermudagrass hay (Cynodon dactylon (L.)Pers.) or female ashe juniper (Juniperus ashei Buchholz) plus Coastal bermudagrass hay during the spring and fall of 1991 in a digestion/metabolism study. Nitrogen concentration of Coastal bermudagrass hay was nearly equal to that of alfalfa hay; nitrogen concentration of ashe juniper and live oak were much lower than those of the hays, and were higher in fall than spring. Dry matter intake and dietary nitrogen were highest for alfalfa hay, intermediate for Coastal bermudagrass hay, and lower for ashe juniper and live oak. Goats retained more nitrogen when consuming alfalfa and Coastal bermudagrass hays than juniper or live oak during fall, but differences were smaller (P > 0.10) during spring. Nitrogen balance was negative for goats consuming live oak in the spring. Nitrogen balance was positive for live oak in the fall and positive for ashe juniper for the spring and fall. Animals fed hay diets had higher levels of urine output than those fed juniper or live oak. Dry matter digestibility of juniper and live oak diets was less in fall than in spring. During fall, dry matter intakes of juniper and live oak were significantly lower than those of alfalfa and Coastal bermudagrass hays. We conclude that both ashe juniper and live oak foliage can provide nutrients for goats but only as portions of diets.

Concentration and composition of monoterpenoids in plant tissue affects a variety of environmental and ecological issues such as plant defenses, plant classification, and phytotoxicity. Developing the techniques for extracting and estimating the concentration and composition of monoterpenoids must be speciesspecific because monoterpenoid storage location varies between species. Ashe juniper f,Juniperus ashei Buchholz) and redberry juniper t,J. pinchotii Sudw) are 2 co-occurring species which differ in palatability and preference. The objective of this study was to determine which of 2 common extraction techniques provided the best estimate of the concentration and composition of monoterpenoids in mature plant tissue. Two extraction techniques were tested by soaking crushed juniper needles in hexane solvent for 6, 12, 18 and 24 hours or by steam distilling samples for 2,4,6, or 8 hours. The extracts were analyzed by using 2 different analytical columns in separate gas chromatographs. The hexane solvent soak, regardless of time in the solvent, yielded a lower total concentration and a decreased compositional diversity of monoterpenoids compared to the steam distillation technique. An g-hour steam distillation yielded the greatest concentration and composition of monoterpenoids. Both types of analytical columns resulted in similar estimates of monoterpenoid concentrations and composition.

Many pinon-juniper ecosystems in the western U.S. are subject to accelerated erosion while others are undergoing little or no erosion. Controversy has developed over whether invading or encroaching pinon and juniper species are inherently harmful to rangeland ecosystems. We developed a conceptual model of soil erosion in pinon-juniper ecosystems that is consistent with both sides of the controversy and suggests that the diverse perspectives on this issue arise from threshold effects operating under very different site conditions. Soil erosion rate can be viewed as a function of (1) site erosion potential (SEP), determined by climate, geomorphology and soil erodibility; and (2) ground cover. Site erosion potential and cover act synergistically to determine soil erosion rates, as evident even from simple USLE predictions of erosion. In pinon-juniper ecosystems with high SEP, the erosion rate is highly sensitive to ground cover and can cross a threshold so that erosion increases dramatically in response to a small decrease in cover. The sensitivity of erosion rate to SEP and cover can be visualized as a cusp catastrophe surface on which changes may occur rapidly and irreversibly. The mechanisms associated with a rapid shift from low to high erosion rate can be illustrated using percolation theory to incorporate spatial, temporal, and scale-dependent patterns of water storage capacity on a hillslope. Percolation theory demonstrates how hillslope runoff can undergo a threshold response to a minor change in storage capacity. Our conceptual model suggests that pinon and juniper contribute to accelerated erosion only under a limited range of site conditions which, however, may exist over large areas.

We examined the distribution and abundance of the short-horned lizard Phry- nosoma hernandezi in Grasslands National Park, Saskatchewan, Canada. Historical records and anecdotal observations were compiled, and new surveys were conducted in 1995 and 1996. A total of 41 individuals, mostly young-of-the-year, were captured in the West Block of the Park in these years. The habitat used by lizards here was juniper dune terrain similar to that inhab- ited by the species in Alberta. Distribution in the West Block appeared to be restricted to the Frenchman River Valley. Twelve adult and subadult lizards were captured in the East Block of the Park in 1995 and 1996, mostly on gentle slopes in the lower reaches of Rock Creek Coulee within 4 km of the 49th parallel. The habitat in the East Block is mixed-grass prairie. Voucher specimens in collections, literature records and anecdotal accounts of this species in Saskatch- ewan almost all originate within the areas examined in this study, indicative of a restricted range in Saskatchewan.

Low nutritional quality and high levels of essential oils result in low consumption of juniper by goats. In this study we examined: (1) if juniper consumption could be increased by exposing goats to essential oils early in life; (2) if goat breeds (Spanish vs Angora) differed in juniper consumption; (3) if differences in juniper consumption were related to detoxification abilities of goats; and, (4) if differences in digestibility and nitrogen or energy balance could explain juniper consumption patterns. In the first experiment, Spanish and Angora goats 6-7 weeks old, were bolused every other day for 1 month with essential oils distilled from redberry juniper (Juniperus pinchotii Sudw.), while control animals received empty capsules. Goats were then offered redberry juniper branches in a 5-day acceptance trial. Spanish goats consumed more (1 < 0.01) juniper during the trial than Angoras. Goats previously dosed with essential oils ingested marginally less (0 < 0.086) juniper than controls. Liver-specific enzymes in blood serum (aspartate aminotransferase and gamma glutamyltransferase) were compared before and after acceptance testing to examine potential liver damage. Spanish goats apparently experienced less tissue damage in response to juniper consumption than Angora goats. A second experiment examined the digestion and metabolism of juniper. Spanish goats consumed more (0 < 0.01) juniper than Angora goats though Angoras digested juniper more completely; probably a result of their lower consumption. The metabolic fate of dietary nitrogen and energy was similar for both breeds and unaffected by exposure to essential oils early in life.

Ashe juniper (Juniperus ushei, Buckholz) is increasing on most sites across the Edwards Plateau of Texas. It is the purpose of this investigation 1) to document the influence of Ashe juniper tree size on understory vegetation and 2) to evaluate how the interaction between tree size and browsing by domestic goats and white-tailed deer modifies overstory/understory relationships. Trees were randomly selected from 2 long-term treatments (browsed and unbrowsed) and analyzed with unlvariate analysis of covariance and multivariate repeated-measures analysis. Without browsing, Ashe juniper is more abundant and its individual influence increases as the size of the tree increases; trees with a canopy diameter < 6.0 m expressed minimal influence on understory vegetation compared to larger trees. When browsers are present at sticient stocking rates to create a browse line on large trees, encroachment of Ashe juniper is slowed, rate of increase of all woody species is reduced, and huge trees cause a shift in species composition directly under the canopy, however cover of all herbaceous species is not reduced. Immediately under the canopy of small browsed trees, herbaceous cover is lower than for unbrowsed trees. Environmental variables responsible for these patterns were litter depth and light penetrating the canopy when the sun is at an angle (during the wlnter). The increased cover of several herbaceous species under the canopy of large browsed trees and at the canopy edge of browsed and unbrowsed trees, indicates the importance of the interaction between canopy cover and the presence of a browse line. Browse lines on Large trees enhance growth and production of cool season species, such as Texas wintergrass (St& leucotricha Trin. & Rupr.) and reduce negative influences (low light, thick leaf litter, etc) on other herbaceous species. At this level of browsing many other palatable species could be reduced or lost from the plant community.

The objective of this study was to determine how rangeland hydrology of oak, juniper, bunchgrass and shortgrass vegetation types is altered by fire. The research was conducted at the Sonora Agricultural Experiment Station on the Edwards Plateau, Texas. Infiltration rate and interrill erosion were measured using a drip-type rainfall simulator. Terminal infiltration rates of unburned areas were significantly greater on sites dominated by oak (Quercus virginiana Mill.) (200 mm hour-1) or juniper (Juniperus ashei Buchh.) (183 mm hour-1) than on sites dominated by bunch-grass (146 mm hour-1) or shortgrass (105 mm hour-1). Terminal infiltration rates on burned areas were significantly reduced on sites dominated by bunchgrass (110 mm hour-1), shortgrass (76 mm hour-1), and on oak sites that were cut and burned (129 mm hour-1). Soil organic matter content (r = .61), total organic cover (r = .59), and aggregate stability (r = .53) were the variables most strongly correlated with infiltration rate. Measured soil structure properties were not altered by fire, therefore, differences in infiltration rate between unburned and burned treatments were attributable to variations in the amount of cover. The terminal infiltration rate of cut and burned juniper sites (162 mm hour-1) was not changed significantly after the fire because the associated good soil structure properties allowed rapid infiltration even after cover was removed. Good soil structure properties were also present on the oak sites, but the infiltration rate significantly decreased as a result of the temporary hydrophobic nature of the soil on this site after burning. Prior to burning, interrill erosion was much lower under the tree sites (oak = 2 kg ha-1; juniper = 34 kg ha-1) than on bunchgrass (300 kg ha-1) or shortgrass (1,299 kg ha-1) sites. After burning, interrill erosion significantly increased for all vegetation types (shortgrass = 5,766 kg ha-1; bunchgrass = 4,463 kg ha-1; oak = 4,500 kg ha-1; juniper = 1,926 kg ha-1). Total organic cover (r = -.74) and bulk density at 0-30 mm (r = .46) were most strongly correlated with interrill erosion.

An inexpensive method of tree felling is needed to precondition dense stands of mature junipers (Juniperus spp.) for the effective use of prescribed burning. The purpose of this research was to determine draft requirements to fell individual juniper trees at different striking heights. These baseline data are necessary to design an elevated chaining technique. Sites in Oklahoma with single-stemmed Ashe juniper (Juniperus ashei Buchholz) (N=40) and Texas with multi-stemmed redberry juniper (Juniperus pinchotii Sudw.) (N=45) were selected for evaluation. A horizontal breaking bar was cabled to an instrumented tractor drawbar for draft force determinations. Data from the drawbar loadcell were stored in a laptop computer data acquisition system. Maximum force to fell junipers was determined at striking heights of 0, 0.6, 0.9, and 1.2 m in Oklahoma and striking heights of 0, 0.6, and 0.9 m in Texas. Force to fell Ashe juniper trees at striking heights of 0, 0.6, 0.9, and 1.2 m averaged 149, 78, 50, and 38 kN, respectively. Striking trees at 0.9 m compared to 0 m (ground level) reduced the felling force by 67% and still uprooted 50% and severed 50% at ground level. With redberry junipers, felling force at striking heights of 0, 0.6, and 0.9 m averaged 81, 14, and 12 kN, respectively. At the striking height of 0.6 m, required draft was reduced by 84% compared to ground level striking, and 67% of the trees were severed at ground level and the remainder were uprooted. To predict force to fell a given size tree, draft was regressed on basal stem diameter in Ashe juniper or total basal stem area in redberry juniper. Based on these data, we concluded an anchor chain modified for elevated striking heights could substantially reduce the tractor drawbar draft for preconditioning of dense stands of juniper by chaining.

Angora and Spanish goats (Capra bircus) were exposed to ashe (Juniperus ashei Buchholz) female, ashe male, redberry (Juniperus pinchotti Sudw.) female and redberry male branches in cafeteria style feeding trials. Preferences were consistent across seasons (except winter). Spanish goats generally consumed more juniper than Angoras. Both breeds preferred ashe over redberry juniper and female over male plants. Concentrations of volatile oils varied significantly between species of juniper and among seasons, but not between sexes. Concentrations of total oils were greater in the spring and summer than in the fall and winter. Concentrations of sabinine+beta-pinene were greater in redberry than ashe for all seasons. Concentrations of myrcene were significantly greater for redberry during the spring and summer. Significant correlation of oil concentration with grams of juniper consumed indicated that specific oils were influencing preference for juniper. Correlations were similar for Angora and Spanish goats, indicating no differences between goat breeds in sensitivity to oils.

Reinvasion of mechanically disturbed juniper communities is possible through contributions from the soil seedbank, seed rain, and the juvenile seedling bank. We compared spatial distribution of the seedbank and seed rain of undisturbed communities to sites where trees were deliberately left as single trees, small mottes of less than 5 trees per group, or large mottes of 5-10 trees per group. Seed density in the litter layer ranged from 1,197 to 1,436 seeds m-2 and in the soil layer from 318 to 617 seeds m-2. Seed rain ranged from 275 to 366 seeds m-2 over all tree arrangements. The treatment associated with single trees caused the litter layer to be removed resulting in the removal of that portion of the seedbank, consequently most seeds (>80%) were found under the canopy of mature, seed-producing trees. Soil disturbance was less severe in small and large motte arrangements, so only 65% of the soil seed bank was under mature trees. In undisturbed communities, the seed population was distributed evenly under tree canopies and in interspaces. Viability and germinability within the seedbank were low (4% and 0%, respectively). Viability of new seed was 47% and germinability was approximately 5%. The juvenile seedling bank contained a sufficient number of seedlings (408 seedlings ha-1) for ashe juniper to regain dominance on the site through growth. There was no advantage to any spatial pattern of tree distribution in terms of invasive potential when fewer than 10 trees ha-1 were left on a site. However, when 20-50 trees ha-1 are left on a site, tree spatial arrangement has a significant effect on reinvasion rates.

The mountain escarpment between Makkah (Mecca) and Taif in Saudi Arabia is wooded, scenic, and relatively undisturbed. Two species of juniper, Palaearctic and Afrotropical, overlap there for thirty kilometers. Extensive development is proposed for the region. In 1991 the National Commission for Wildlife Conservation and Development sponsored a university student- staff study of an area of 600 km2. This paper gives the results of their survey with recommendations for protection of the natural vegetation, the establishment of a nature reserve with related recreational facilities, and for sustainable development.

Basal cover, density, biomass, and species richness of the understory were measured in concentric zones from the stem bases of large redberry juniper (Juniperus pinchotii Sudw.) trees to 6 m beyond their canopy edges on a shallow, rocky soil and 2 deep soils in the northern Edwards Plateau of Texas. The juniper-driven successional processes of tree dominance, debilitation of understory dominants, influx of subsidiary species, and the general reduction in diversity, density, and biomass of the herbaceous species were evident on all 3 sites. Juniper interference intensified with increasing proximity to the stem bases. Biomass and basal cover of the herbaceous understory responded to a greater extent than did density and species richness 2 years after large redberry junipers were killed with soil injections of picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid). Herbaceous biomass responses after junipers were killed indicated that the sphere of influence of large junipers was more extensive on the shallow soil than on the deep soils. Herbaceous biomass in the presence of interference by large junipers on the Kimbrough, Angelo clay loam, and Tulia loam soils was 1,300, 1,780, and 1,290 kg ha-1, respectively, compared to 2,140, 2,140, and 1,560 kg ha-1 2 years after the junipers were killed on the 3 sites, respectively. Projected herbaceous biomass when juniper populations on the sites develop into closed-canopy woodlands was 320, 880, and 270 kg ha-1 for the Kimbrough, Angelo clay loam, and Tulia loam soils, respectively.

The effects of avian foraging and post-foraging behavior on seed dispersal patterns of Ashe juniper (Juniperus ashei) were examined. We predicted that 1) flocking species would be more efficient at dispersing seeds than non-flocking species, and 2) among flocking species, flock attributes such as size, structure, and post-foraging behavior would determine efficiency of seed dispersal by each species. We were unable to evaluate single forager species because of low sample sizes. Among flocking species foraging behavior of birds (time spent feeding, number of fruit taken per visit, number of visits, and flock size and cohesion) determined the quantity of the seed crop removed by each species. Post-foraging behavior (departure direction from feeding trees, perch type selected, and distance moved from feeding trees) determined the probability that seeds dispersed by a dispersal agent will land in a safe site for germination. Two of 15 species of avian frugivores that fed on Ashe juniper, the American robin (Turdus migratorius) and cedar waxwing (Bombycilla cedrorum), were the most important dispersers. Differences in foraging and post-foraging behavior between American robins and cedar waxwings yielded two distinct seed dispersal patterns, "clumped" (high density) by waxwings and "scattered" (low density) by robins.

Changes in woodland vegetation integrate the consequences of livestock grazing intensity, the alteration of fire regimes, and possible climate alterution, as well as other factors. Quantitative measurements of these changes, if taken over sufficient intervals, can allow evaluation of conservation management strategies. In 1933, vegetation along a 37-km transect in southern Pine Valley, Utah was described from circular 19-m2 plots located every 42 m. The major intermediate management treatment has been reduction of grazing pressure by introduced animals, although a fraction of the area was chained and burned in 1977. During a period climatically and phenologically similar to the original study, we reexamined representative segments of this transect by a more detailed updating of the original "square-foot-density" method. Significantly greater shrub and perennial grass covers (more than threefold increases) were found in 1989, even where overall dominance is still by pinyon-juniper [Pinus monophylla (Torrey & Fremont) and Juniperus osteosperma (Torrey) Little]. This change is more obvious on steeper slopes away from roads and water, where both human and livestock disturbances would be expected to be minimized. Except in the chained portion, the observed shifts in dominance/diversity are contrary to widely accepted expectations.

The optimum combination of 3 range improvements was determined for private lands on Utah ranches. While many promising range improvements are available, determination of which alternatives to implement must consider the total ranch operation. Linear programming (LP) makes it possible to simultaneously determine the profit maximizing combinations of range improvements and how these improvements will affect the total ranch operation. The study examined 3 range improvements (revegetation, burning, and chemical brush control) for big sagebrush (Artemisia tridentata Nutt.) and pinyon-juniper (Pinus spp.-juniperus spp.) on upland loam and upland shallow loam range sites. Net present value analysis and an LP model were used to identify the most efficient alternative, the limiting constraints, and the optimum levels and combinations of alternatives. The optimal solution ran 238 brood cows compared to 196 for the typical Utah ranch. Burning big sagebrush or pinyon-juniper infestations on crested wheatgrass (Agropyron desertorum Fisch. ex Link) foothill ranges was the most profitable range improvement. Annual net cash incomes after burning sagebrush or pinyon-juniper on the upland loam site were $37,873 and $37,770, respectively, compared to $31,278 on the typical Utah cow-calf operation. The optimal solution will change as input and product prices change. The model was designed for application to specific ranches rather than to make general recommendations for the typical Utah ranch.

Ashe juniper (Juniperus ashei) and Texas persimmon (Diospyros texana) fruit use and seed dispersal potential by four carnivores were studied on the Edwards Plateau region of Texas. Feces were examined to determine presence of seeds and frequency of occurrence by month from August 1989 to February 1990. Use of fruit species by month followed the pattern of fruit ripening of the two plant species. Texas persimmon fruit was consumed primarily between September and January while Ashe juniper fruit was consumed from October through February. Because large numbers of seeds are present in feces and few are destroyed in mastication and digestion all carnivores studied are considered legitimate dispersal agents of Ashe juniper and Texas persimmon. Dispersal efficiency of carnivores, however, is low due to the location of dispersed seeds (feces) and the clumped seed dispersal patterns. The role of temperate carnivorous mammals as seed dispersal agents of fruit-producing plants has been neglected in the literature (Herrera, 1989). Among tropical mammals, monkeys (Howe, 1980; Estrada and Coates-Estrada, 1984) and bats (Morrison, 1978; Fleming, 1981, 1986; Heithaus, 1982; Gribel, 1988) have been studied intensively in recent years although they have long been recognized as important seed dispersal agents (Ridley, 1930; Krefting and Roe, 1949; van der Pijl, 1982). Recently, the importance of herbivorous mammals in seed dispersal has been documented (Janzen, 1981, 1982, 1984) and to a lesser extent the importance of carnivorous mammals has been noted (Stiles, 1980; Estrada et al., 1984). We know of only one study dealing thoroughly with the extent and significance of carnivores (Herrera, 1989) in seed dispersal of temperate fruit-producing plants. Furthermore, little information is available regarding fruit use by North American carnivorous mammals and the associated potential for seed dispersal. This neglect is curious, because it is well known that many carnivores commonly consume fruits (Davis, 1978; Chapman and Feldhamer, 1982). The fact that early work on seed dispersal placed emphasis on coevolution (Smith, 1970; Snow, 1971; McKey, 1975; Howe and Estabrook, 1977) of fruit and dispersers could explain this neglect. Most temperate carnivores have large home ranges and are nocturnal in habits, making any study of them difficult. Because of this difficulty, most information gathered on carnivores and their possible importance as seed dispersers has been obtained through indirect means: analysis of stomach contents and collection of fecal material and the subsequent analysis of their seed contents (Herrera, 1989). However, little information has been reported regarding seed dispersal potential. Herein we report information gathered on selected carnivorous mammals of the Edwards Plateau of Texas, with respect to fruit use and potential seed dispersal of Ashe juniper (Juniperus ashei) and Texas persimmon (Diospyros texana). Data were collected on the diet of four carnivorous mammals known to include fruits in their diets. Particular importance was given to the season and degree of utilization of these fruits by the carnivores and their potential role in the dispersal of seeds is discussed. MATERIALS AND METHODS-The study was conducted between August 1989 and February 1990 at the Texas A&M University Agricultural Experiment Station at Sonora, Texas. The 1430-ha Station is located 45 km SE of Sonora at approximately 1000W and 300N. Vegetation is generally grassland with scattered individuals or mottes (clumps) of live oak (QuerHWESTERN RALIST 38(2):141-145 E The Southwestern Naturalist TABLE 1--Percent frequency of occurrence (%) and numbers (X ? SD, range) of Ashe juniper and Texas persimmon seeds in carnivore feces collected on the Edwards Plateau, Texas, during the fall and winter months of 1989 and 1990. Texas persimmon Ashe juniper

Tebuthiuron [N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]N,N'-dimethylurea] controls small trees in regrown pinyon-juniper woodland chainings. Precise applications by hand minimize cost and damage to forage plants. Little information exists on the applicability of local trials to varying Intermountain sites slated for reinvestment. We conducted 2 balanced factorial experiments at well-separated sites in the Great Basin and Colorado Plateau. Four rates (0.12, 0.25, 0.50, and 0.75 gm a.i. per 130 dm3 crown volume) of tebuthiuron boluses were applied to tree stembase, mid-crown, or dripline placements. Four size classes (12-99, 100-299, 300-599, and 600-1099 dm3 crown volume) of Utah juniper [Juniperus osteosperma (Torr.) Little] and single needle (Pinus monophylla Torr. and Frem.), and Rocky Mountain (P. edulis Engelm.) pinyon trees were treated in September 1985. Defoliation and mortality levels were estimated 24 and 36 months following treatments. Both sites received highly similar amounts of herbicide and cumulative precipitation. Analysis of variance showed that the presence and strength of main effects and first order interactions was largely site-specific. Pinyon was more susceptible than juniper at tither site. Medium-sized and large saplings were apparently more readily defoliated than seedlings and small saplings. Dosage effects were generally nonlinear for both species. The highest, most rapid and most uniform defoliation and mortality of trees resulted from application of tebuthiuron at the stem bases. This placement option has strong operational advantages and minimizes damage to forage plants beneath trees.

The concentrations, distribution, and longevity of tebuthiuron [N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N'-dimethylurea] and its metabolites in Utah junipers [Juniperus osteosperma (Torr.) Little] killed by tebuthiuron are not known, causing concern about potential residues and their release into the environment from decaying plants or burning wood. Utah juniper trees killed by tebuthiuron at 3 north-central Arizona locations were assayed for tebuthiuron and its metabolites by gas chromatography with flame photometric detection. Foliage, twigs, stems, and litter from recently killed trees averaged 13.3 +/- 0.4, 0.4 +/- 0.1, 0.4 +/- 0.1, and 4.0 +/- 6.6 mg/kg of tebuthiuron plus its metabolites, respectively. Dead stems averaged 0.5 +/- 0.4 mg/kg in sapwood, 0.1 +/- 0.1 mg/kg in heartwood, and 0.4 +/- 0.7 mg/kg in bark, 3 to 9 years after application. Root bark averaged 1.1 +/- 1.9 mg/kg, and root wood averaged 0.5 +/- 1.4 mg/kg. Although long lived, these small tebuthiuron residues should have little potential environmental harm if treated Utah juniper wood is used as firewood or fence posts.

Previously grazed pinyon-juniper woodlands in Grand Canyon National Park, northern Arizona, were studied to determine the effects of past and present grazing. The occurrence and biomass of cryptogamic crust were compared for five sites in and around the Park along a continuum from never grazed to recently grazed. All sites were similar in soil characteristics, elevation and overstory dominants. Cryptogamic crust was quantified using visible cover estimates and the chlorophyll a content of the crust as an indicator of biomass. Visible crust cover was reduced almost 80% on grazed (5.2%) as compared to ungrazed (23.3%) sites. Crust biomass, as estimated by chlorophyll a content, was reduced on grazed (3.1 ,tg cm-2) compared to ungrazed (9.9 ,tg cm-2) sites. There were no significant differences in species presence and absence data. Significant correlations existed between cryptogamic crust cover and the composition of the respective vascular plant communities, marked by a reduction of grasses and an increase of bare soil.

Eighty-two plant and 26 small vertebrate taxa were identified from four radiocarbon dated woodrat (Neotoma sp.) midden samples from a rock crevice at 655 m elevation on Picacho Peak, Pinal Co., Arizona. A late Wisconsin (11,100 to 13,170 YBP) pinyon-juniper-oak woodland dominated by Pinus monophylla (singleleaf pinyon) and Juniperus cf. osteosperma (Utah juniper) and J. erythrocarpa/monosperma (redberry/oneseed juniper) shifted to a more xeric juniper-oak woodland/chaparral in the early Holocene (9,420 to 10,280 YBP). Extralocal species that no longer live on Picacho Peak were 29.9% in the late Wisconsin and 20.1% in the early Holocene with the greatest changes in longlived trees, shrubs, and succulents. The biogeographic and taxonomic significance of Scaphiopus hammondi (western spadefoot) and the ecological adaptability of Phrynosoma platyrhinos (desert horned lizard), Micranthe whitneyi (elf owl), and Neotoma cf. albigula (white-throated woodrat) are discussed. All taxa in the vertebrate fauna are widespread in desertscrub and desert-grassland, still occur in the area, and enter woodlands only at the upper or northern edges of their ranges. The typical inhabitation of woodlands by these vertebrates and anomalous associations in the flora probably reflect the expansion of equable climates that now characterize ecotonal habitats during the late Wisconsin glacial. Analyses of plant remains preserved in ancient woodrat (Neotoma sp.) middens are providing excellent developmental sequences for local floras and vegetation for the last 20,000 to 40,000 years on rocky slopes in the southwestern United States and northern Mexico (Van Devender et al., 1987a). During the last glacial (the Wisconsin) period, woodlands expanded into the modern Sonoran Desert in southwestern Arizona and adjacent California (111* to 113*W). Pinyon-juniper-oak woodland dominated by Pinus monophylla (singleleaf pinyon) was at 600 to 1,555 m elevation with a xeric Juniperus californica (California juniper) woodland down to about 300 m, and Larrea divaricata (creosotebush) desertscrub at lower elevations along the Colorado River and around the head of the Gulf of California in Sonora and Baja California (Van Devender, 1990). Animal remains are much less common than plants in woodrat middens but provide insight into faunal responses to changing climate and vegetation (Van Devender and Mead, 1978; Van Devender et al., 1979; Mead and Phillips, 1981; Mead et al., 1983). Here we report the pla and vertebrate remains in woodrat middens from Picacho Peak, Arizona. MATERIALS AND METHODS-Picacho Peak was an isolated butte in Picacho Peak State Park rising from 550 m elevation at the base to 1,030 m at the top (Briscoe, 1967; Shafiquallah et al., 1976; Yeend, 1976). The nearest mountains of larger size were the Santa Catalina Mountains just north of Tucson (55 km SE) that rose to 2,790 m elevation. The lowest elevation near Picacho Peak was 520 m along the Santa Cruz River (3 km SW). The local climate was characterized by infrequent winter freezes, hot summers, and biseasonal rainfall from Pacific winter frontal storms and the subtropical summer monsoon. Mean temperatures for Eloy (15 km NW) at 475 m were 10.8*C for January and 32.3*C for July with extremes of 10.6*C and 47.2*C (Sellers and Hill, 1974). Precipitation was 215 mm/year with 40.6% falling from June to September. Picacho Peak was in the relatively well-watered Arizona Upland Subdivision of the northeastern Sonoran Desert (Shreve, 1964; Turner and Brown, 1982). The vegetation on rocky slopes and bajadas was dominated by Cercidium microphyllum (foothill paloverde), Olneya tesota (ironwood), and Carnegiea gigantea (saguaro) in This content downloaded from 207.46.13.149 on Mon, 03 Oct 2016 06:10:19 UTC All use subject to http://about.jstor.org/terms September 1991 Van Devender et al.-Late Quaternary plants and vertebrates 303

Herbage biomass for blue grama (Boutdoua grdlis [H.B.K. Lag& pinyon ricegrass (Pfph&tu&un jimbriatum [H.B.K.] Hit&c.), New Mexico muhly (Muhihkgfa pcsrciflorcl Buckl.), other grasseq and forbs was estimated on 25 pinyon-juniper stands of varying overstory cover on the Fort Stanton Experimental Ranch insouthcentral New Mexico. Negative 2”d degree polynomial curvea best expressed the relationshipa between total understory and blue grama biomass and overstory canopy cover. Positive polynomial relationships were shown for cool-season graazs, New Mexico muhly, and pinyon ricegrass. Reducing pinyon-juniper canopy cover would likely increase blue grama production and reduce production of New Mexico mubly and pinyon ricegraas.

Some sediments exposed in cutbanks of streams in canyons in northeastern New Mexico and adjacent Oklahoma are considered to be filled-in beaver ponds and associated fringing meadows. Exposures rich in mollusk remains yielded small but important late Pleistocene and Holocene faunas. Five localities, approximately 31,000 to 500 YBP, were sampled. We present our hypothesis for the genesis of the valley fills, and discuss the zoogeographic significance of Thomomys bottae, Sigmodon hispidus, Microtus ochrogaster, and Microtus pennsylvanicus. The Cimarron River and its tributaries flow through the north-central corner of the Oklahoma Panhandle and adjacent parts of New Mexico. The river has cut through Tertiary basalts and Mesozoic strata (Schoff and Stovall, 1943) to form a rugged, dissected topography of mesas and can- yons. The land is semi-arid, and level areas sup- port short-grass prairie. Rough and broken land is clothed in juniper and Colorado pinyon (Pinus edulus).

The food habits and distribution by elevation of black bears (Ursus americanus) in Banff National Park, Alberta, were investigated during a 3-year radio? telemetry study. Analysis of feeding signs indicated that the typical year is divided into the following bear food seasons: 1) green-up (den exit to mid-June),when horsetails (Equisetum sp.) and graminoid vegetation (grasses, sedges and rushes) formed the major portion of the diets of bears, with importance values of 38.2 and 34.2%, respectively; 2) ant (mid-June to mid-July), when bears consumed ants (Formicidae) and ant larvae to a large extent (69.3%); 3) buffaloberry (mid-July to end-August), when bears fed upon buffaloberries (Shepherdia canadensis: 91.4%) once they ripened in mid-summer; 4) post-buffaloberry (end-August to den entry), when, once buffaloberries had fallen from the bushes, bears switched to alternate foods such as crowberries (Empetrum nigrum: 85.1 %), bearberries (Arctostaphylos uva-ursi: 11.1%) and juniper (Juniperus communis) berries (0.7%). Some bears were found to feed primarily upon crowberries during this season, while others mainly ate bearberries. The mean elevation at which all collared bears were located ranged from 1,500 -1,543 m during the first 3 seasons, but increased to 1,694 m during the post-buffaloberry season. Some bears, however, stayed at low elevations (x = 1,463 m) during the fall and fed upon bearberries. Those that fed upon crowberries during the post-buffaloberry season had a mean elevation of 1,768 m, while those that fed upon high-elevation bearberries and white? bark pine (Pinus albicaulis) nuts had a mean elevation of 1,818 m.

Effects of redberry juniper (Juniperus pinchotii) on species composition and biomass production of the herbaceous layer were evaluated for 3 yr on an ungrazed site and a site with past cattle grazing in western Texas. Herb production and grass production decreased as juniper cover increased. Species composition differed between ungrazed and formerly grazed sites, and the formerly grazed site produced less grass biomass than the ungrazed site during each year. The inverse relationship between juniper cover and grass production was linear on the ungrazed site and logarithmic on the formerly grazed site during all 3 yr of the study, suggesting that grazing resulted in a competitive advantage to the overstory species. This relationship persisted for at least 5 yr following release from grazing. Nearly all studies of overstory-understory relations in pinyon-juniper woodlands have shown an inverse logarithmic relationship between overstory cover of pinyons (Pinus spp.) and junipers (Juniperus spp.) and herb production (Arnold et al., 1964; Jameson, 1967; Short et al., 1977; Clary, 1987). In closed-canopy stands, junipers can exclude virtually all herbaceous vegetation (Buechner, 1944; Burkhardt and Tisdale, 1969). The impact of cattle grazing on the juniper-herb relationship has not been studied, probably because ungrazed sites are rare in pinyon-juniper communities. The influence of grazing on production and composition of grasslands has been the subject of considerable research (see Sims et al., 1978; Sims, 1988), but woodlands have received considerably less attention. In general, the competitive balance among herbaceous species is shifted by grazing (Harper, 1977), and grazing often reduces grassland productivity (Sims, 1978). Compensatory growth in response to grazing may overcome losses in productivity (McNaughton, 1979). The latter phenomenon has been the focus of considerable discussion, primarily as a population-level process (McNaughton, 1986; Belsky, 1986). Juniperus pinchotii (redberry juniper) is an important overstory species on semiarid Texas grasslands (Scifres, 1980). It is capable of sprouting following top removal (Correll and Johnston, 1970). Woody plant response to cattle grazing and environmental factors has been described for redberry juniper-mixed grass communities (McPherson et al., 1988). However, overstory-understory relations and herb response to grazing have not been addressed. The objective of this study was to quantify the relationship between redberry juniper cover and herbaceous vegetation under contrasting precipitation and livestock grazing regimes. I Present address: Forest-Watershed Sciences Program, School of Renewable Natural Resources, University of Arizona, Tucson 85721

Burning had the greatest impact on soils beneath burned debris piles. Electrical conductivity, phosphorus, potassium, percent nitrogen, and percent organic carbon increased significantly at all soil depths the first year after burning debris piles. No impact was evident on phosphorus, percent nitrogen, and percent organic carbon by the second year. Impacts on burned interspace areas were generally less pronounced and few impacts were measured the second year. Impact of burning on soil pH was minor. Burning as a management tool is becoming increasingly important within the pinyon-juniper (Pinus spp.-Juniperus spp.) type. Wright et al. (1979) have recently reviewed the role and use of fire in pinyon-juniper plant communities. Wells et al. (1979) have indicated that under rangeland conditions, effects of fire on organ

(2) Longevity may be related to growth rate; slower growing junipers can live longer, and the life-span can be correlated with the growth rate in the early years. Variability of growth rates makes comparison of trunk girths of specimens from different sites very unreliable as a basis for estimating age. (3) Seed production in older junipers is reduced. Sex ratios are often not 1:1, and past history may be a factor in explaining sex ratios of present-day populations. (4) Juniper populations are often roughly even-aged, and in these cases study of the age and expected longevity of the bushes allows for prediction of the ultimate life-span of such populations in the absence of regeneration. This is relevant to the management of juniper on nature reserves.