Darrell N. Ueckert

Dietary similarity of some primary consumers.

The dry—weight composition of the diets of richardson ground squirrels (Citellus richardsonii), mormon crickets (Anabrus simplex), and six species of grasshoppers (Xanthippus corallipes, Circotettix rabula, Aeropedellus clavatus, Melanoplus infantalis, Melanoplus bruneri, and Melanoplus alpinus), collected at Prairie Divide, Colorado, was determined. Many food plants were shared by these herbivores. Vetch (Astragalus spp.), sandwort (Arenaria fendleri), fungi, parry oatgrass (Danthonia parryi), bluegrass (Poa spp.), fringed sagebrush (Artemisia frigida), dandelion (Taraxacum officinale), and sedge (Carex spp.) were major foods. Bluegrasses, vetch, and sandwort would probably become limiting if population peaks of several of these herbivores coincided. The ranking of the food niches of these herbivores from specialized to generalized based on mean indices of dietary similarities is X. corallipes, A. clavatus, C. rabula, M. alpinus, A. simplex, M. bruneri, C. richardsonii, and M. infantalis. Males ate fewer...

Effect of burning on infiltration, sediment, and other soil properties in a mesquite-tobosagrass community.

Highlight: Burning had a minimal effect on rainfall infiltration and sediment load in runoff from a mesquite-tobosagrass community on slopes less than 1%. Most soil physical properties that affect infiltration on these heavy clay soils were not altered significantly by burning. Potential soil loss in runoff can be minimized by burning under relatively moist conditions. Larger soil aggregates were broken down by burning and had not returned to equilibrium on 5-year-old burns. Trends in levels of soil organic carbon, salinity, sodium, and potassium following burning varied with degree of soil cracking, which is a function of soil moisture.

Economics of redberry juniper control in the Texas Rolling Plains

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.

Germination of fourwing saltbush seeds: interaction of temperature, osmotic potential, and pH.

Establishment of shrubs and other forage plants on arid and semiarid rangelands and salt-contamhtated sites may be enhanced ifecotypes with ability to germinate and establish under moisture stress and high temperatures can be identified. The interactive effects of temperature, osmotic potential, and pH on germination were evaluated with seed from 4 populations of fourwing saltbush [Atr@lex canescens (Pursh) Nutt.] from western Texas. Predicted optimum temperature (15 to 18’ C) from osmotic potential by temperature response surfaces for germination of 3 populations (Valentine, Grandfalls, and San Angelo) were similar to those reported for populations of fourwing saltbush from other western states. Germination of seed collected near Texon, Texas was significantly (JYO.01) affected by media pH range 6 to 9. Seed from the Texon population germinated under lower osmotic potentials compared to the other 3 populations. Total germination of all four populations was enhanced by osmotic potentials lower than 0 MPa. Seed from the Texon population may possess germination characteristics more suitable for arid-hmd seeding than those from populations near Valentine, Grandfalls, and San Angelo, Texas. Fourwing saltbush [Atriplex canescens (Pursh) Nutt.], a native, evergreen shrub, is absent or rare on most western Texas rangeland, probably because of the prevalence of continuous, yearlong grazing by cattle, sheep, and/or goats. The species has been successfully used for rehabilitation of oilwell reserve pits where high concentrations of soluble salts and sodium prevented acceptable establishment or growth of other species.1 Our preliminary grazing trials suggest that fourwing saltbush may be valuable for balancing the seasonal deficiencies of protein in native forages (D.N. Ueckert, unpublished data). Fourwing saltbush frequently grows on relatively dry, saline Authors are reseach associate, professor, and research associate, Texas Agricultural Experiment Station, 7887 N Hwy 87, San Angelo 76901 and Grounds Keeper, University Lands, the University of Texas System, Midland, Texas. This article is approved by the Director, Texas Agricultural Experiment Station as TA-20556. This research was partially funded by University Lands, the University of Texas System. Mention of a trade name does not constitute a guarantee or a warranty of the product by the Texas Agricultural Experiment Station and does not imply its approval to the exclusion of other products that also may be suitable. Manuscript accepted 28 May 1985. ‘McFarland, M.L. 1984. Revegetation of oilwell reserve pits in west Texas. MS Thesis, Texas A&M University, College Station. soils, suggesting that its seed may be adapted for germinating under conditions of limited moisture. Springfield (1966) hypothesized capacity to germinate under dry field conditions may vary among geographic strains or ecotypes of fourwing saltbush. Therefore, ecotype selection should improve potential for revegetating arid and semiarid rangelands. Fourwing saltbush germinates best at low temperatures (13 to 24’C). Light is not required unless seeds are less than 4 months old or under alternating temperature regimes (Springfield 1970). Fourwing saltbush emergence was adversely affected by high (53°C) compared to low (39%) temperature regimes (Sosebee and Herbel 1969). Buffered pH in the range 3.0 to 8.0 did not affect germination of 6 Australian saltbush species (Beadle 1952). However, saltbushes are seldom found growing in acidic soils (Foiles 1974). Dewinging fourwing saltbush seed in a hammer mill hastens germination and is a standard practice. The bracts contain about 10% saponin, a germination inhibitor (Nord and Van Atta 1960). Tolerance of fourwing saltbush seed to low media osmotic potential during germination may be genetically controlled. Springfield (1966) reported fourwing saltbush seed germinated at -1.50 MPa of manitol-induced moisture stress, but total germination and germination rate decreased with increasing moisture stress. However, seeds of 3 of 6 seed accessions exhibited greater total germination at -0.30 MPa than at -0.03 MPa, and total germination of 2 accessions was greater at -0.70 MPa than at -0.03 MPa. Springfield concluded that additional research was needed to confirm whether germination of some fourwing saltbush strains was actually stimulated by low media osmotic potentials. Fourwing saltbush seed tolerated greater levels of moisture stress during germination at 17’C than at higher or lower temperatures (Springfield 1966). This suggests that moisture stress may be less limiting to germination when temperatures are near optimum. Field germination of seeds can be better understood if the interactive effects of seedbed parameters are known (Kaufman and Ross 1970, Sharma 1976). Objectives of this study were to (1) evaluate the interaction of temperature, osmotic potential, and pH on germination of fourwing saltbush seeds, and (2) determine whether germination characteristics varied among naturally occurring populations of the species in western Texas. JOURNAL OF RANGE MANAGEMENT 39(l), January 1966 43 Methods and Materials throughout the 4-week trials. This procedure minimizes changes in Seed from about 100 native fourwing saltbush plants were handharvested in December 1981 at each of 4 sites in the western Edwards Plateau and Trans-Pecos resource areas of Texas, including: 1 km west of San Angelo (Tom Green County); Texon (Reagan County); 10 km south of Grandfalls (Pecos County); and 5 km northwest of Valentine (Jeff Davis County) (Table 1). Fourwing Table 1. Collection sites of fourwing saltbush seeds used in evaluation of the interaction of temperature, osmotic potential and pH upon germinr-

Population Density and Biomass of the Desert Termite Gnathamitermes Tubiformans (Isoptera: Termitidae) in a Shortgrass Prairie: Relationship to Temperature and Moisture

Fluctuations in the population density and biomass of Gnathamitermes tubiformans (Buckley) in the upper 30.2 cm of soil were determined over a 2—yr period in a shortgrass community in Garza County, Texas. Linear stepwise multiple regression was used to determine the relationships of termite population densities with environmental factors in this soil increment. Termites were not present in the upper 30.2 cm when the soil temperature at 15 cm was < 9 degrees C. Termite population densities in the upper 30.2 cm of soil varied significantly between years as a function of air and soil temperatures, precipitation and soil moisture. Consideration of data from relatively short time periods alleviated many difficulties in identifying biologically important causal factors. In a year of above—normal precipitation, temperature was the most important factor affecting desert termite population densities, whereas during a year of below—normal precipitation, soil moisture was the most important factor. Biomass of desert termites in the upper 30.2 cm of soil averaged 5.83 g/m2 (live—weight) over the 2—yr period and reached a peak of 23.03 g/m2 during September 1972. The abundance of tunnels and chambers of G. tubiformans decreased with depth in the soil profile. Termites migrated below 124 cm in subterranean galleries to avoid soil temperatures < 10 degrees C.

Revegetation of oil well reserve pits in west Texas.

On-site dispod of drilling fluids frquently causes severe, longterm disturbance of rangeland soils. The effects of mulch on establishment and standjng crops of seeded kochia [Koch& swpar& (L.) sChrad.1, King Ranch bluestem [Bothhchftm is&emwn (L.) Ifen& Lebmann lovegrass (Erugros& &nau&na Nees), kleingrass ‘Selection 75’ (Punieum wkuarum L.), alkali sacaton [Sparobolus airoides (Torr.) Torr.1, and fourwing saltbusb [Atr@kx ~(III~~E~IL~ (Pursh) Nuttl, and transplanted founving saltbush were evaluated on 4, recently covered oil well reserve pits in Reagan County Texas, in 1981 and 1982. On-site disposal of drilling fluids resulted in substantfal to large increases in sodium adsorption ratios (SAR) and concentrations of soluble salts, primarily sodium chloride, in reserve pit soils. Mulching with 4,500 kg/ha of weathered hay had no effect, but irrigation was essential for establishment and growth of the seeded species on severely contaminated soils (EC* 71 to 114 dS m-‘, SAR 33 to 127). Mulching improved establishment and yields of seeded King Ranch bluestem and kleingrass on reserve pit soils with EC. values of 9 to 11 dS m-l and SAR values of 12 to 16. Appliation of 5.1 cm of supplemental water and mulching reserve pit soils with EC. values of 3 to 7 and SAR values of 5 to 9 stimulated establishment of competing vegetation, which tended to decrease establishment and yields of seeded and transplanted species. Establishment and yields of transplanted fourwing saltbush were acceptable with or without mulching or irrigation. Survival of fourwfng saltbusb transplants was near 199% on moderately contaminated soils and 26 to 39% on severely contaminated soils.

Ecotypic variation in selected fourwing saltbush populations in western Texas.

Fourwing saltbush [A tr@kx cmescens (Pursh) Nutt.] seedlings from 4 western Texas tetraploid populations were established in uniform nurseries at San Angelo, Barnhart, and Marfa, Texas, in 1981 to determine relative adaptability to these respective environments. Survival and canopy development of the ecotypes were similar at the site with the most favorable growing conditions (San Angelo), but the ecotype originating nearest the planting site tended to have greatest survival and canopy size where site conditions were less favorable. Additional shrub attributes evaluated at the !3an Angelo site included: leaf, current year’s stem, and wood phytomass, seasonal nutrient concentrations, and floral develop ment and phenotype. prediction equations utilizing plant canopy measurements were used to estimate weights of plant components. Variation in canopy size and yields among individual plants within ecotypes masked detection of significant (PrO.05) differences among ecotypes, but ecotypes from arid environments tended to be larger and to have greater yields than those from more mesic environments. Concentrations of crude protein (CP), phosphorus (P), and digestible organic matter (DOM)of leaves and stems were similar among the 4 ecotypes. Floral development of the ecotype from the most mesic environment progressed at a faster rate than that of ecotypes from more xeric environments. Ecotypes from xeric environments tended to have fewer staminate plants, but more plants with no sex expression than ecotypes from more mesic areas.

Emergence and survival of honey mesquite seedlings on several soils in West Texas

Results from field and laboratory studies indicated that germination and emergence was adequate on soils that supported heavy densities, low densities, or no mesquite for establishment of dense populations of honey mesquite. Absence of honey mesquite or low densities of this species on soils where seeds are readily deposited by natural mechanisms could not be explained by soil chemical or physical properties that might inhibit seed germination or emergence of seedlings. In field studies, seedling emergence was not related to the density of honey mesquite presently growing on six range sites. At the end of the first growing season and at 1 year after planting, seedling survival was inversely related to density of honey mesquite. Two years after planting, seedling survival was not related to density of mesquite supported by the six soils. In this short-term study, competition with associated herbaceous vegetation overshadowed the effects of soil properties on survival of honey mesquite seedlings.

Impact of a white grub (Phyllophaga crinita) on a shortgrass community and evaluation of selected rehabilitation practices.

During the spring of 1973, white grubs, PhyZZophugu crinita (Burm.)‘, at a density of 46.3/m2, reduced cover of perennial grasses by 88% in localized areas of a shortgrass community in Scurry County, Texas. Forbs and broom snakeweed were not affected. Chlordane applied to the soil surface at 3.36 kg/ha did not control white grubs. Chlordane, nitrogen fertilization (112 kg/ha of N), and a combination of the insecticide-fertilization treatments did not appreciably enhance rehabilitation of white grub-denuded rangeland. Seeding with introduced grasses was not successful because of inadequate precipitation, heavy grazing by lagomorphs on the small areas, and competitive effects of buffalograss. Forbs and broom snakeweed were not important in the early seral stages of secondary succession on the study site, but common broomweed and common sunflower were dominants on other denuded sites in the area. Most plant species had recovered by the end of the second growing season without fencing to control livestock grazing. White grubs (Coleoptera: Scarabaeidae), the larvae of June beetles, are among the most destructive of soil-dwelling insects (Hewitt et al. 1974). However, no quantitative evaluations of their effects on rangeland vegetation have been published. The adult June beetles feed on foliage of broadleaf and coniferous trees and cause little damage, but the larvae feed largely on the roots of grasses. Large acreages of rangeland in the northwestern Texas panhandle, northeastern New Mexico, Colorado, Kansas, and Nebraska have been severely damaged by white grubs (Saylor 1940; Schumacher 1959; Daniels 1966; Anon. 197 1 a; Anon. 197 1 b). Moderate damage by white grubs is often attributed to drought or low levels of soil fertility. The author is associate professor, Department of Range and Wildlife Management, Texas Tech University, Lubbock. His present address is Texas A&M University 7&t A ‘cultural Research and Extension Center, Route 2, Box 950, San Angelo, Texas This study is approved as Texas Tech University, College of Agricultural Sciences Publication No. T-9-200. The author expresses appreciation to Dr. R.D. Gordon, Systematic Entomology Laboratory, U.S.D.A.S.E.A., Beltsville, Maryland, for taxonomic determination of insect specimens. Manuscript received August 23, 1979. ’ Coleoptera: Scarabaeidae. However, high population densities of white grubs can kill rangeland vegetation, crops, pastures, and lawns (Anon. 1959; Randolph and Garner 196 1). Feeding by white grubs can also provide a mode of entry for disease organisms which can eventually kill infected plants (Drake 1964). Graber et al. (193 1) reported that liberal fertilization and favorable growing conditions reduced the degree of injury by white grubs to Kentucky bluegrass (Pea prutensis L.) pastures. Most species of white grubs have a 3-year life cycle, and most of the damage to plant roots occurs during the 2nd year. White grubs may cause damage every year if several broods co-occupy the same area, but usually the severe injury occurs in 3-year cycles (Anon. 1959). A localized die-off of range vegetation in the southwestern Rolling Plains resource area of Texas during the spring of 1973 was attributed to severe root-feeding by the white grub Phyllophaga crinitu (Burm.). This study was initiated to quantify white grub damage to rangeland vegetation and to evaluate fertilization, insecticide treatment, and seeding for rehabilitation of rangeland severely damaged by white grubs. Methods and Materials This study was initiated in May, 1973, and continued through September, 1975, on the Lefors Ranch, 3 km west of Dermott in Scurry County, Texas. Average annual precipitation of the area is 48 cm. About 70% of the annual precipitation falls during the April to September growing season. Soils are of the Mansker and Potter series and textures are loams to clay loams. Topography is rolling with 1 to 5% slopes. The major grasses in this shortgrass community include buffalograss (Buchloe ductyloides Nutt.), red threeawn (Aristidu longisetu Steud.), and hairy tridens [Erioneuron pilosum (Buckl.) Nash]. Major forbs include common broomweed [Xunthocephalum drucunculoides (D.C.) Shinners] and leatherweed croton [Crotonpottsii (Klotzsch) Meull. Arg.]. Broom snakeweed [Xunthocephulum surothrue (Pursh) Shinners] is a common half-shrub or shrublet. Localized honey mesquite (Prosopis glundulosu Ton-. var. glundulosu) occurs on deeper soils. On May 22, 1973, the following treatments were applied to grubdenuded plots: (a) 3.36 kg active ingredient (a.i.)/ha of chlordane JOURNAL OF RANGE MANAGEMENT32(6), November 1979 445 (octachloro-4,7-methano tetrahydroindane); (b) 112 kg/ha of nitrogen as ammonium sulfate; (c) 3.36 kg a.i./ha chlordane + 112 kg/ha nitrogen as ammonium sulfate. Untreated check plots were established on a grub-denuded and adjacent undisturbed rangeland. Each treatment was replicated three times in a randomized complete block design. Plot size was 6.1 by 13.4 m. The insecticide was applied to experimental plots with a 203-cm boom, with nozzles on 50-cm centers, mounted on bicycle wheels. Fertilizer was applied with a whirl-wind type hand spreader. The experimental plots were not fenced and were grazed continuously during the study at a moderate stocking rate with a cow-calf herd. Population density of P. crinitu was determined before application of treatments and on June 6,1973, May 2 1,1974, and June 19,1975, by excavating soil in ten, 30.5 by 30.5cm quadrats to 20 cm deep. Soil was sieved over 0.5-cm mesh hardware cloth to facilitate counting of larvae, pupae, and adults. Below ground plant biomass was determined on May 10, 1973, by extracting roots from ten randomly selected soil cores (8 1.07 cm2 by 30.5 cm) taken from grub-denuded rangeland and from ten similar cores taken from adjacent undisturbed rangeland. Each soil core was washed over a soil sieve (0.42-mm mesh) to separate the soil and roots. Root samples were oven-dried, weighed, and ashed to determine an ash-free weight for each sample. Foliar cover was determined on May 24, 1973, and subsequently on October 18, 1973, October 25, 1974, and September 25,1975, by the point-frame technique (Levy and Madden 1933). One hundred points were observed in each plot on each sampling date. Readings were taken at ten equidistantly spaced intervals along a permanent line transect across the diagonal of each plot. Any above-ground plant part hit by the pin point was recorded as a hit. Differences between treatments in foliar cover for major plant species and vegetation categories were determined by analyses of variance of total hits per plot. An auxiliary study was conducted to evaluate seeding with introduced grasses for rehabilitating white grub-denuded rangeland. Plots 6. lby 13.4-m were tilled to 8 cm deep on May 23, 1973, on white-grub denuded rangeland. Kleingrass (Panicurn colorutum L.) and Ermelo weeping lovegrass [Erugrostis curvula (Schrad.) Nees var. Ermelo] were seeded in single plots at 3.4 kg P. L. S./ha and 3.1 kg P.L.S./ha, respectively, in rows on 50-cm spacings. Seeded plots were fenced to exclude livestock. Results and Discussion Initial Impact on Plant Community White grub-infested areas were localized and did not constitute a major range management problem in Scurry County, although ranchmen who had patches of dead grass were concerned that infestations might spread and become a major problem. Most white grub-denuded areas were 0.1 ha or less in area, but some covered 1 ha or more. In early May, 1973, all grass plants in infested areas appeared to be dead. Grass roots had been completely severed at 2 or 3 cm below the soil surface, and most grass plants had fallen to a horizontal position, exposing the severed roots. Foliar cover of perennial grasses had been reduced 88% compared to adjacent undisturbed rangeland, while cover of all live herbaceous plants was reduced 83% (Table 1). Litter cover increased 63 % on white grub-denuded areas compared to adjacent undisturbed rangeland, because of the deposition of dead perennial grasses. Bare soil increased 20%. Cover of forbs and half-shrubs was not affected by the white grubs (Table 1). Below-ground plant biomass in the upper 30.5 cm of soil in white grub-denuded areas was reduced to 3,478 kg/ha compared to 6,143 kg/ha on adjacent undisturbed rangeland (43% reduction). In late May, 1973, the mean population density of P. crinitu was 46.3/m2 in the upper 20 cm in white grub-denuded areas. No larvae, pupae, or adults were found at depths greater than 20 Table 1. Cover (%) of vegetation, litter, and bare soil on white-grub infested rangeland and adjacent undisturbed rangeland in Scurry County, Texas on May 24, 1973.

Fourwing Saltbush Seed Yield and Quality: Irrigation, Fertilization, and Ecotype Effects

Abstract Clones of superior pollen- and seed-producing plants of 4 fourwing saltbush (Atriplex canescens [Pursh] Nutt.) ecotypes were planted in a seed orchard in west-central Texas to determine if seed production and quality could be enhanced by irrigation and fertilization. Subplots of nitrogen (N) at 112 kg·ha−1, phosphorous (P) at 112 kg·ha−1, N + P at 112 + 112 kg·ha−1, or no fertilizer were superimposed on irrigated or dryland main-plots. Neither irrigation nor fertilization affected estimated seed yields or utricle fill during the third growing season after planting. Fertilization did not affect seed germination of any of the saltbush ecotypes on irrigated plots or that of the 2 more xeric ecotypes (Grandfalls and Valentine) on dryland plots. Fertilizer N on dryland plots increased germination of the San Angelo ecotype, and N + P increased germination of the Texon ecotype. Estimated gross value of the first seed crop was about