Now showing items 1-20 of 34

• #### Germination Requirements of Green Needlegrass (Stipa viridula Trin.)

Germination requirements of green neddlegrass (Stipa viridula Trin.) were studied because of its potential for use in revegetation of disturbed lands. The effects of temperature, light, physiological, and mechanical treatments on germination of green needlegrass seed from 4 sources were examined to determine requirements for maximum germination and possible causes of dormancy. Optimum temperatures for germination were 20 degrees C (constant) and 20-15 degrees C (16 hr-8 hr alternation). Germination was highest in constant darkness. Greatest germination of the most dormant source occurred when seeds were either prechilled or treated with gibberellic acid and the lemma and palea was clipped with a razor blade. The results indicated that dormancy of green needlegrass seeds was associated with a deficiency of endogenous gibberellins and with mechanical and permeability restrictions imposed by the lemma and palea.
• #### Fuel-Load Reductions Resulting from Prescribed Burning in Grazed and Ungrazed Douglas-fir Stands

Prescribed understory burning was carried out in both grazed and ungrazed Douglas-fir stands on the University of Idaho Experimental Forest. Burning conditions were moderately cool with 10-hr time-lag fuel moisture varying from 11 to 19%. Preburn and postburn fuel loadings were determined by use of the planar intersect method. Preburn data indicated greater fuel accumulations in grazed stands, 55,460 kg/ha, as compared to ungrazed stands, 44,710 kg/ha. Difficulty in achieving a satisfactory rate-of-spread and fire intensity was encountered due to the combined effects of a very dry summer followed by a wet fall. Moist conditions on the study site, lack of fine fuels, and accumulation of heavy fuels in the grazed portion produced a burn of patchy nature. Fire rate of spread varied from 0 to 183 cm/minute with flame height up to 91 cm. Result was a fuel reduction of 60.2% in the grazed stand and 35.2% in the ungrazed stand. Prolonged grazing in this area had created a dense, overstocked stand with insufficient fine fuels to carry a fire, which severely limited the effectiveness of prescribed burning.
• #### Fire-Induced Mortality of Redberry Juniper [Juniperus Pinchotii Sudw.]

Redberry juniper mortality was determined following spring broadcast burns in 1979 and 1980, and individual-plant burns with 3 heat treatments in 1981. Mortality varied from 1 to 100% and was related to bud zone location, plant size, site, and growing conditions. During years of above average precipitation, mortality averaged 70% for plants with the bud zone above the soil surface contrasted to 3% for plants with the bud zone partially below the soil surface. Plant size and site factors such as slope and soil surface stability appeared to affect the rate at which the bud zone was buried by soil, thus producing a fire resistant plant. Plant mortality was significantly increased across all size classes and sites when burns were conducted under hotter conditions and followed by a dry growing season.
• #### Fistula Sample Numbers Required to Determine Cattle Diets on Forest and Grassland Ranges

The variation among esophageal fistulated (EF) cattle in diet nutritive content and botanical composition selection was evaluated on forest and grassland range in the Blue Mountains of eastern Oregon during the summer of 1976. Botanical composition of diet samples was determined with microhistological analysis. Nutritive value was evaluated by analyses for crude protein, acid detergent fiber, permanganate lignin, and in vitro organic matter digestibility. Four collections were made from 4 EF heifers during each of 4 28-day periods on each vegetation type. Collections were alternated between morning and afternoon on each vegetation type. EF cattle selected diets of different (P<.05) botanical composition and nutritive quality in the early morning compared with the late afternoon. They grazed open grassland areas in the morning and shaded areas in the afternoon. Several more EF cattle and collections were required to determine diet botanical composition than nutritive quality on both the forest and grassland. A minimum of 4 EF cattle and 4 collections were needed to adequately sample diet nutritive characteristics on the grassland and forest pastures. The data indicated collections should be rotated between morning and afternoon on ranges supporting a mosaic of grassland and forest plant communities.
• #### Fire History at the Forest-Grassland Ecotone in Southwestern Montana

The history and influence of fires was studied at the forest-grassland ecotone in high valleys of southwestern Montana. Investigations were focused upon several sites having early landscape photographs and modern retakes that allow for detection of vegetational changes. Fire intervals were determined for these sites by analyzing fire scars on trees. Prior to 1910, mean fire intervals at Pseudotsuga forest-grassland ecotones were 35 to 40 years, and probably shorter in grassland proper. No fires were detected on the study areas after 1918. Photographic comparisons and field inspections show a substantial increase in mountain big sagebrush (Artemisia tridentata subsp. vaseyana) and conifers since 1900.
• #### A Comparison of Four Methods Used to Determine the Diets of Large Herbivores

Esophageal fistulation, stomach content analysis, fecal analysis, and forage utilization were compared as techniques for determining food habits of large herbivores. Each technique was evaluated based upon information collected using bi-fistulated (esophageal and rumen) sheep during 2 study phases. In the first study phase, microscope slide mounts were made of plant fragments collected from the esophagus, rumen, and feces of 10 confined sheep fed a hand-composited mixture of forage. Dietary composition as determined by each technique was compared to the original feed. Stomach content analysis and fecal analysis produced dietary estimates higher in grasses and lower in forbs than the known feed values. Esophageal fistulation results were not significantly different from the known feed values. In the second study phase, esophageal, rumen, and fecal collections were gathered from 16 sheep grazing a common plant community. Ocular estimates of forage utilization were made concurrently. All data were converted to percent composition on a dry weight basis for comparisons. Significant differences in percent diet composition among techniques occurred for 18 of the 31 plant species consumed. Diets determined by stomach content analysis and fecal analysis were significantly higher in grasses and lower in forbs than those determined by esophageal fistulation and ocular estimates of utilization.
• #### 'Magnar’ Basin Wildrye—Germination in Relation to Temperature

Basin wildrye (Elymus cinereus) is potentially a very valuable forage species adapted to saline/alkaline range sites in the Great Basin. Poor seed fill and low germination have limited the usefulness of this species for range revegetation. The recently released cultivar 'Magnar' tends to overcome these obstacles and offers a higher potential for use of basin wildrye on rangelands. In this study we compared the germination of 'Magnar' and its sister selection accession P-15590 at 55 constant and alternating temperatures. The seeds of both selections are highly germinable with optimum regimes for temperatures centered around 20 degrees C. 'Magnar' seeds had 82% germination at moderate seedbed temperatures and 32, 28 and 37% germination at colder, warmer, or widely fluctuating seedbed temperatures, respectively. Germination of 'Magnar' seeds was most rapid at what became optimum temperature regimes for germination. Germination was increasingly delayed at extremely warm, cold, or widely fluctuating temperatures.
• #### Evaluation of a Fertilized 3-Pasture System Grazed by Yearling Steers

A grazing trial comparing fertilized and unfertilized 3-pasture systems has shown that the addition of 56 kg nitrogen (N)/ha substantially improved forage and beef production. Forage production from the fertilized system was increased by 46% over the unfertilized system while per acre beef gains were increased 35%. Each 3-pasture system utilized crested wheatgrass for spring and early summer, native mixed grass prairie for mid and late summer and Russian wildrye for fall grazing. Comparison of Hereford and Angus-Hereford crossbreds indicated a slight gain advantage for the crossbred animals, although the increase was not statistically significant. The addition of the biuret supplement Kedlor was found to improve gains of steers grazing the native pastures in late summer but resulted in decreased gains on fall-grazed Russian wildrye pastures. Analysis of the forage samples showed that in all samples except one, the addition of N fertilizer increased the protein content.
• #### Cattle Trampling of Simulated Ground Nests under Short Duration and Continuous Grazing

Trampling by cattle on simulated ground nests were compared between continuous (CONT) grazing at 8.0 ha/steer and short duration grazing (SDG) at 5.3 ha/steer. Trampling losses were similar under CONT grazing (15%) and SDG (9%) at a nest density of 1/ha. Percentage trampling loss did not increase at higher nest densities under either grazing regime. Nest survival curves indicated a loss rate of 2.21%/wk under CONT grazing and 2.09%/wk under SDG. The data from this study suggest there is no reason for concern that SDG with cattle will increase trampling loss of ground nests over CONT grazing.
• #### Distribution of Dry Matter and Chemical Constituents in Plant Parts of Four Florida Native Grasses

Because of the selective nature of grazing livestock, the use of whole plant samples to estimate the nutritional potential of forages may be misleading. During this 2-year study, the distribution of dry matter (DM), crude protein (CP) in vitro organic matter digestibility (IVOMD), and concentrations of P, K, Ca, Mg, Mn, Fe, Cu, and Zn were determined in the individual leaf blades, leaf sheaths, nodes plus internodes, and infloresences of creeping bluestem (Schizachyrium stoloniferum), lopsided indiangrass (Sorghastrum secundum), maidencane (Panicum hemitomon), and wiregrass (Aristida stricta) when they were in the anthesis stage of maturity. Most of the DM was in the nodes plus internodes (avg. 45%), while the leaf blades (avg. 18%) generally made up the smallest amount of the total plant DM. In a progression from the bottom to top of the plant the CP, IVOMD, and most of the mineral concentration of the different leaf blades, sheaths, and nodes plus internodes increased. Crude protein, IVOMD, and most of the minerals of the grasses were higher in leaf blades, followed by sheaths, and nodes plus internodes. When compared with other grasses, maidencane had a higher proportion of CP and minerals in the leaves and nodes plus internodes and a higher percentage of plant weight in these parts. Wiregrass was found to be similar to creeping bluestem and indiangrass in CP and most minerals, but IVOMD of wiregrass parts were lower. Dietary requirements for dry, pregnant cows for P, N, Mg, and Cu might not be met by any part of the 4 grasses, while apparently adequate levels of Fe, Mn, and Zn could be provided by each part. Leaf blades and infloresences had sufficient Ca concentrations for dry pregnant cows.
• #### Economics of Gypsum and Elemental Sulfur as Fertilizers on Subclover-Grass Pastures in Northern California

Sulfur deficiencies are widespread on the rangeland soils of California and the application of sulfur-bearing fertilizers has been widely recognized as a promising range improvement on these soils. Considerable work has been done on the management and ecological aspects of sulfur fertilization of California rangeland; however, little or no economic analysis of this improvement exists. Using existing data from subclover-grass pastures in northern California to derive aggregate production functions, optimal application rates of sulfur applied as elemental sulfur and gypsum were determined using standard marginal analysis. Both elemental sulfur and gypsum proved to be profitable means of increasing both winter and total yearly production when either harvested hay or grazed forage (AUM's) were considered as products. Using 1981 material costs and product prices applied to total yearly hay production, the optimum rate of sulfur applied as gypsum with 3 years residual was 251 kg/ha for an increased profit of $101/ha/yr over unfertilized pastures. The optimum rate of elemental sulfur was 147 kg/ha for a profit increases of$93/ha/yr. When total yearly grazed forage was considered the product, optimum application rates were 195 kg/ha of sulfur as gypsum and 126 kg/ha for elemental sulfur yielding profit increases of $46/ha/yr and$48/ha/yr, respectively. Optimal application rates and profits were lower for both hay production and grazed forage when winter production was optimized.
• #### Ecological Characteristics and Control of Gambel Oak

Manipulation of Gambel oak for enhanced rangeland values must be in accord with ecological principles to ensure desired success. Failures in controlling Gambel oak have occurred because the growth patterns, morphological characteristics, and carbohydrate storage patterns of the species have not been taken into account. However, recurrent control will continue to be necessary since grass dominated systems should not be considered to be climax in Gambel oak dominated systems. Existing initial and maintenance control methods appear to offer only short-term solutions, which often result in more troublesome long-term management problems.
• #### Vehicle Impacts on Northern Great Plains Range Vegetation

Three levels of vehicle impact (2, 8, 32 trips over the same tracks) were applied on rangelands near Ashland, Mont., using a four-wheel-drive Chevrolet Blazer with mud and snow radial tires. The impacts were applied each month, May to September, on previously unimpacted range. Canopy coverage measurements and ground and aerial photography were used to evaluate the impact effects. In the year of impact, canopy coverage measurements showed increasing damage to the vegetation as the number of trips increased. Damage was greater on very moist to wet soils than on dry soils. Vegetation measurements the year following the impacts did not show carry-over damage to vegetation from the 2 and 8 trip treatments, except for range impacted when the soils were wet. These measurements did show carry-over damage to shrubs from 32 trips, but not to grasses and forbs. Ground and aerial photographs in the first year after the impacts still showed visual evidence of 8 and 32 trip impacts. Aerial photographs taken the second year after the impacts still showed evidence of all 32 trip treatments and some 8 trip treatments. Color infrared film gave superior results when the vegetation was actively growing. Color film was superior when the vegetation had dried.
• #### Vegetation Changes from 1935 to 1980 in Mesquite Dunelands and Former Grasslands of Southern New Mexico

On the Jornada Experimental Range in southern New Mexico, 2 belt transects, 30.5 cm in width and totaling 2,188 m in length, were established in 1935 on 2 areas where honey mesquite (Prosopis glandulosa Torr.) was spreading into black grama [Bouteloua eriopoda (Torr.) Torr.] grassland. Maps were made of the transects which portrayed the vegetation occurring in each of the 7,180 contiguous, $0.09\text{-}{\rm m}^{2}$ plots along the transect. The vegetation on the transects in 1980 was compared to that portrayed by the transect maps made in 1935. One transect had been read in 1950 and 1955. During the 45-year period mesquite attained complete dominance and many new mesquite dunes formed. Black grama had a relatively high frequency in 1935 but had completely disappeared by 1980, both on an area grazed by livestock and on an area protected from grazing. Mesa dropseed [Sporobolus flexuosus (Thurb.) Rydb.], fluffgrass [Erioneuron pulchellum (H.B.K.) Tateoka] and broom snakeweed [Xanthocephalum sarothrae (Pursh) Shinners] increased in abundance, even during the drought period between 1950 and 1955. Only 25% of the perennial forb species encountered in 1935-55 were found in 1980.
• #### Seedbed Ecology of Winterfat: Fruits Versus Threshed Seeds

This series of studies compare winterfat establishment from whole fruits and seed. The studies have demonstrated that the long hairs of the fruit function as 'anchors' which help the radicle of a germinant to penetrate and begin growth into the soil. Other factors associated with the fruit also aid plant establishment. These factors have to do with better positive geotropic response of the radicle and with seedling vigor as measured by radicle growth in the soil. For these reasons, seedling establishment is better when fruits are broadcast, rather than when threshed seed is broadcast or planted at a 0.64 cm depth. Soaking fruits in water at 0 degrees C for 48 hours significantly improved germination rate and percentage. Recommendations are made for field planting winterfat.
• #### Short-term Changes in a Cottonwood-Ash-Willow Association on a Grazed and an Ungrazed Portion of Little Ash Creek in Central Arizona

Recovery of a cottonwood-ash-willow association from overgrazing has been extremely limited over a 4-year period. Seedling reproduction and herbaceous cover has increased; however, overstory tree species composition has not changed. Tree growth was not affected by grazing. The younger, associated, codominant tree species differed in composition between the grazed and ungrazed plots.
• #### Summer Food Habits of Domestic Sheep in Southeastern Montana

The summer food habits of sheep were investigated in a sagebrush-grass rangeland in southeastern Montana. Grasses and sedges made up 96% of the diets. Prairie sandreed (40%), needleleaf sedge (28%), and western wheatgrass (20%) were the most important foods. Forbs and shrubs made up less than 1 and 3% of sheep diets, respectively.
• #### Attentiveness of Guarding Dogs for Reducing Predation on Domestic Sheep

Dogs used to protect domestic sheep from predators are expected to be attentive to the animals they guard. However, 40% of the sheep producers cooperating in our experimental program to assess the potential of Old World dogs to deter predation in the United States have expressed dissatisfaction with their dog's attentiveness. In contrast, European shepherds appear satisfied with their dogs. In order to find the causes of this apparent difference, a series of measured observations was made in Italy, and data on 4 different strains of imported guarding dogs working in the U.S. were analyzed. The results indicate that the 4 strains are significantly different in attentiveness, although overall it was remarkably similar to the actual attentiveness of Italian dogs. The attentiveness of livestock guarding dogs can be maximized for U.S. sheep producers by (1) selecting strains for superior attentive behavior and (2) adjusting management systems slightly to take advantage of the dogs' capabilities.
• #### An Improved Method for Attaching the Esophageal Fistula Bag

A simple, surgically established skin "neck loop" was tested for holding the collection bag in position on esophageal fistulated steers. The loop eliminated the need for a girth strap and reduced the time required for attaching and detaching the collection apparatus.