Journal of Range Management, Volume 35 (1982): Recent submissions
Now showing items 21-40 of 207
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Short Duration Grazing at the Texas Experimental Range: Effects On Forage QualityVariation in percent crude protein (% CP) of available forage was examined at the Texas Experimental Ranch as a function of grazing treatment, plant species, physiological age of plant tissue, and season. Results indicate that % CP content varied as much as function of physiological age of plant tissue as a function of plant species. Although quantity of crude protein of total standing crop averaged significantly more in an ungrazed treatment than in a short duration grazing treatment, % CP was generally greater in the grazed than the ungrazed treatment. It is suggested that an increase in quality of forage may be a primary mechanism facilitating energy flow through short duration grazing systems whereby dramatic increases in livestock carrying capacity may be realized.
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Short Duration Grazing at the Texas Experimental Ranch: Weight Gains of Growing HeifersTotal and average daily gains of Hereford/Angus crossbred growing heifers were contrasted between a continuously grazed (CG) treatment and a 10-pasture, 1-herd rapidly rotated short duration grazing (SDG) treatment. Stocking rate in the CG was 0.48 ha/AUM, a moderate rate, while stocking rate in the SDG treatment was 0.24 ha/AUM. Trials were conducted during the 1978 and 1979 growing seasons. Both total and average daily gains were similar in both treatments both years. Because of the two-fold difference in rate of stocking, production/ha was approximately double in the SDG to that in the CG treatment. It is tentatively concluded from the results of this and previous studies that a properly managed SDG system may satisfactorily support livestock at rates of stocking appreciably greater than that normally expected from conventional grazing schemes.
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Short Duration Grazing at the Texas Experimental Ranch: Effects on Aboveground Net Primary Production and Seasonal Growth DynamicsThe effects of short duration grazing on aboveground net primary productivity (ANPP) and seasonal growth dynamics were evaluated. Total ANPP was estimated to be 234 g/m2 in 1978 in the ungrazed control plot as compared to 330 g/m2 in the grazed treatment plot. ANPP estimates in 1979 were 352 and 268 g/m2 in the ungrazed and grazed treatments, respectively. Close examination of growth dynamics suggest that under certain environmental conditions grazing accelerated vegetative growth.
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Seasonal Diurnal Variation in Composition of Cow DietsSeasonal diets between fall 1977 and spring 1979 were collected in morning and evening from esophageally fistulated cows in the Post Oak Savannah of east-central Texas. Chemical content of diurnal diets were similar within a season except CP was higher in evening collections as compared to morning collections during fall. Cows appeared to select for energy (IVDOM) over CP. Botanical composition of morning and evening diets differed only during summer. Since the cows spent more time during hot summer afternoons in the shade of woody plants, less grass and more forbs, vines, and woody vegetation were selected. Research based on morning diet collections only might result in biased samples. Recognition of nutritional and environmental stresses with potential to alter grazing behavior of animals is critical for accurate sampling of livestock diets.
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Sample Preparation Techniques for Microhistological AnalysisA study was conducted to determine the influence of sample preparation procedures on the ratio of identifiable to nonidentifiable fragments in diet samples analyzed by microhistological analysis. The number of identifiable fragments on slides was significantly higher when samples were soaked in either bleach or sodium hydroxide in conjunction with use of Hertwig's clearing solution compared to the control, which involved the use of only Hertwig's clearing solution. The percentages by weight of grasses, forbs, and shrubs in two prepared diet samples were more accurately estimated when either sodium hydroxide or bleach was applied in comparison with the control. However, some plant species or plant parts may be destroyed by bleach or sodium hydroxide. Therefore, diet materials should also be examined through standard procedures before the decision is made to apply one of these treatments.
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Root Biomass on Native Range and Mine Spoils in Southeastern MontanaResearch was conducted on native range and revegetated strip mine spoils near Colstrip, Montana, in August of 1975 to determine the weight and distribution of root biomass at five locations. Study sites included native range in excellent, good, and poor condition; a naturally revegetated 40-year-old leveled, ungrazed strip mine spoils; and a 5-year seeded and fertilized mine spoils. Total root biomass was highest on the 5-year-old seeded and fertilized mine spoils. Good condition native range had a higher root biomass than excellent or poor condition native range. The root biomass of the 40-year-old mine spoil did not differ from excellent condition native range. Root biomass distribution in the four zones studied did not differ between sites. Over 55% of the root biomass was in the upper 15 cm of the soil profile at all five locations.
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Responses of Crested Wheatgrass and Russian Wildrye to Water Stress and DefoliationCrested wheatgrass (Agropyron desertorum, Fisch Schult) and Russian wildrye (Elymus junceus, Fisch) plants were subjected to three levels of water stress (13, 2.6, and 1.8% soil moisture), in interaction with 4 defoliation levels (0, 40, 60, and 80% defoliation). Plants were clipped biweekly using the height-weight ratio method to determine the assigned defoliation level and leaf water potential $(\Psi _{1})$ was measured by pressure bomb. Following the final clipping at ground level a 40-day recovery period was allowed while maintaining plants at field capacity (13% soil moisture). Leaf water potential measurements showed significant differences between species, among three water stress levels, and within four defoliation levels. Water stress and defoliation levels significantly affected foliage yield, root biomass, and plant recovery. Heavy defoliation (80%) resulted in a 100% death loss for both species at wilting point (1.8% soil moisture). Light defoliated (40% at field capacity) produced more total dry matter than undefoliated plants maintained at field capacity or wilting point. Maximum root biomass was found in undefoliated plants of crested wheatgrass grown at field capacity. Significant differences in root production were also found among water stress and defoliation treatments. No plant recovery occurred among plants maintained at wilting point and defoliated at 80%. However, plants defoliated at 40 and 60% under 13 and 2.6% soil moisture exhibited considerable regrowth. In general crested wheatgrass out-yielded Russian wildrye in every treatment and was more resistant to defoliation and water stress.
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Response of Small Mammals to Livestock Grazing in Southcentral IdahoThe effects of livestock grazing on populations of wildlife have been addressed in two recent studies on the INEL Site. However, studies were performed by measuring indices of abundance among areas where different practices had occurred prior to initiation of study. There is no proof that differences detected among the areas actually resulted from the land use practices. Studies should be conducted with replication and strict controls before correlated data can be accepted as indicators of cause and effect relationships. The large variation in the occurrence and densities of small mammals among areas with the same or similar uses suggests the need for further studies to resolve conflicting conclusions.
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Response of Needle-and-Thread and Western Wheatgrass to Defoliation by GrasshoppersField and greenhouse studies were conducted to measure changes in plant growth resulting from grasshopper defoliation. All data indicated that as grasshopper grazing intensity on needle-and-thread grass increased, total root weight decreased. A greenhouse study with western wheatgrass showed that heavy grazing (80% removal of top growth) for a 16-day period reduced top growth 82%, root growth 85%, crown growth 81%, rhizome growth 100%, and depth of root penetration 49%. Field observations indicated that most grasshopper defoliation of needle-and-thread grass and western wheatgrass occurs after seasonal growth has been completed.
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Response of Chihuahuan Desert Mountain Shrub Vegetation to BurningThe effects of fire on vegetation in the desert mountain shrub community were studied on 3 to 7-year-old burned sites near the northern limits of the Chihuahuan Desert. Coverage and frequency of redberry juniper (Juniperus pinchotii) and frequency of whiteball acacia (Acacia texensis) were lower, while frequencies of catclaw mimosa (Mimosa biuncifera) and skeleton goldeneye (Viguiera stenoloba) were higher on burned sites when compared with unburned paired plants. Lechuguilla (Agave lecheguilla), sotol (Dasylirion leiophyllum), and sacahuista (Nolina spp.) suffered losses in excess of 50% on burned sites. With the exceptions of sideoats grama (Bouteloua curtipendula) and bull muhly (Muhlenbergia emersleyi), all grasses had recovered or showed increases by the end of three growing seasons. All grasses had recovered or increased on 6 to 7-year-old burns. Recovery of burned plants was predominately by vegetative means, suggesting that periodic fires can be used to maintain or even increase grass coverage at the expense of shrubs in this community.
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Reseeding by Eight Alfalfa Populations in a Semiarid PastureEight alfalfa populations were seeded in a dryland pasture in northern Utah. Densities of mature plants, seeds, seedlings, and 1-year-old plants were measured in each of 3 years. The populations did not differ for mature plant stands or seed production. There was a higher rate of seedling survival for populations that primarily originated from Medicago sativa rather than M. falcata. All populations had some one-year-old plants persisting to replace mature plants killed by disease or rodents.
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Recovery of Streamside Woody Vegetation After Exclusion of Livestock GrazingRemoval of livestock grazing along a small, perennial desert stream allowed the reestablishment of woody vegetation (Salix amygdaloides) in the riparian zone within 10 years.
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Recovery of Cryptogamic Soil Crusts from Grazing on Utah Winter RangesRange exclosures located throughout Utah in cool desert shrub communities were analyzed to determine, (1) the response of cryptogamic crusts to grazing, (2) soil variables that influence the development of cryptogamic crusts and (3) the time needed for reestablishment of cryptogamic communities after disturbance. The amount of lichen, moss and algal cover was found to be considerably reduced by domestic grazing. Sites with moderate to high as opposed to light cryptogamic cover were characterized by significantly heavier textured soils and greater salinity. Cryptogamic cover increased from 4% to 15% during the first 14-18 years of exclusion from grazing, but increased only 1% during the next 20 years. Reestablishment of a cryptogamic crust occurs in at least 14-18 years and possibly sooner.
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Rapid Extraction of Sesquiterpene Lactones from Sagebrush for Use as Taxonomic MarkersThe sesquiterpene lactones of sagebrush occur in glandular trichomes on the leaf surface and can be extracted in 1 to 2 minutes with chloroform. Analysis of this extract by thin-layer chromatography can be used as a taxonomic characteristic.
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Rangeland Management and the EnvironmentManagement of the rangelands of the world for multiple use is a complicated process. Rangeland productivity can be increased by several means. However, some of these means have undesirable ecological consequences. There is a need for integration of range ecosystems management on a world-wide scale under an ecological framework.
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Punch Planting to Establish Grass SeedPerennial grasses are difficult to establish from seed in the Southern Great Plains. The conventional planting practice is to plant grass seeds 1 to 2 cm deep in the soil; but that soil layer often dries quickly, thus preventing plant establishment. I investigated punch planting, which may avoid the problem of soil drying around grass seeds. Punch planting is defined as the placement of seeds in open, small-diameter holes, punched in the soil to a much greater depth than conventional planting. Under drying conditions, punch planting produced satisfactory stands for 5 grasses, but conventional planting produced failures. Where the soil was kept wet, both methods produced satisfactory grass stands. Optimum depth of punch planting was related to seed size and seedling vigor. Small-diameter holes (0.6 cm) produced best plant emergence, because soil at the bottom of these holes dried slower than at the bottom of large holes. Punch planting may offer a solution to the problem of seeding failures.
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Prescribed Burning during Winter for Maintenance of BuffelgrassNeither a single burn during late winter nor a second burn 2 years later reduced the density of mixed brush dominated by blackbrush acacia, honey mesquite, and twisted acacia which had invaded buffelgrass seedings on the South Texas Plains. Based on canopy cover and height, most woody species had recovered to preburn status after two growing seasons. Buffelgrass responded by a flush of spring growth during the year of burning and cumulative herbage production exceeded that of unburned areas for three growing seasons after the single burn. However, during dry growing conditions, less buffelgrass herbage was produced on burned than on unburned areas. A second burn tended to increase buffelgrass herbage production compared to the single burn. However, when moisture became limiting, less herbage was also produced on the twice-burned areas. Disappearance of buffelgrass, attributed primarily to grazing, closely paralleled herbage production, with the greatest disappearance occurring the first growing season after the burn.
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Preliminary Study of Some Insects Associated with Rangeland Shrubs with Emphasis on Kochia prostrataThe introduced and potentially useful range shrub Kochia prostrata (prostrate kochia) and its naturalized herbaceous congener K. scoparia (annual kochia) both appear to be excellent hosts for the lygus bug (Lygus desertinus). However, lygus bugs were abundant only on concentrated Kochia stands and not on K. prostrata growing intermixed with other plant species. Therefore, it is recommended that prostrate kochia be planted in mixtures with other plant species in range rehabilitation projects so that high insect populations are not encouraged. Lygus bugs spend much of the summer on both Kochia species but move to associated plants when the associates flower. Although lygus bugs were found in abundance on prostrate kochia, no major damage to the plant was evident. Prostrate kochia apparently is not the overwintering egg host-plant for lygus bugs. On prostrate kochia, seven other identified insect species (six families) as well as several unidentified taxa were also collected. These additional species were mostly short-time residents in low numbers. Flea beetles (Psylloides punctulata) were occasionally abundant.
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Potassium Content of Three Grass Species during WinterThe potassium content of little bluestem (Schizachrium scoparium (Michx.) Nash), kleingrass (Panicum coloratum L.), and brownseed paspalum (Paspalum plicatulum Michx.) declined following plant senescence and frost. The potassium content of herbage of little bluestem and brownseed paspalum reached levels below the requirements of cattle by February during two winters. Kleingrass leaves retained green tissue the first winter yielding higher potassium levels. Little bluestem had reached senescence and had low levels of potassium by November. Herbage of the three species was also subjected to soaking treatments to simulate frost damage and quantify losses due to leaching. Potassium levels declined with soaking in freeze damaged herbage as time of exposure increased. Soaking treatments did not significantly affect the potassium content of fresh live herbage.
