CAPES / Os objetivos deste trabalho foram avaliar a influencia de períodos de pastejo em trigo duplo propósito sobre a taxa de decomposição das plantas e liberação de nutrientes (N, P, K, Ca e Mg) bem como a produtividade de soja cultivada na sequencia em sistema de semeadura direta. Os tratamentos foram arranjados em delineamento blocos ao acaso com duas repetições. Os tratamentos foram os seis períodos de pastejo (0, 21, 42, 63, 84 e 105 dias) e a taxa de decomposição do material residual destes, foi avaliada pela técnica de litter-bag. A percentagem de biomassa e nutrientes no compartimento mais prontamente decomponível aumentou à medida que aumentou os períodos de pastejo, principalmente devido ao efeito do animal sobre a renovação dos tecidos foliares, o que resultou em uma maior taxa de decomposição da palhada e de liberação de nutrientes para o solo e, consequentemente para a cultura da soja cultivada na sequencia em sistema de integração lavoura pecuária. Entretanto a produtividade de grãos de soja reduziu com o aumento dos períodos de pastejo principalmente devido à diminuição de resíduo de matéria seca sobre o solo. / The aims of this work were to evaluate the influence of dual purpose wheat grazing periods on plant decomposition rates and nutrient release (N, P, K, Ca e Mg) and soybean yielded cultivate in sequence in no-till systems. Treatments were laid out as a random block design with two replications. The treatments were six grazing periods (0, 21, 42, 63, 84 e 105 days), on continuous stocking rate grazing method. From these treatments, dual purpose wheat biomass and nutrients decay constants were evaluated along 7 different field incubation periods (0, 15, 35, 63, 98, 139 e 196 days after soil deposition) by the litter bag technique. The percentage of biomass and nutrients at the easily decomposable compartment increases with the increase of grazing periods, due to the influence of the animal over the plants tissue turnover, which results in highest decomposition rate and nutrients release to the soil and consequently to the soybean cultivated in sequence on crop-livestock system. However the soybean grains yielded reduced with the increase grazing periods mainly due to the diminished of dry matter residue over the soil.

The four major ecological variables, soils, climate, vegetation and fauna, were studied from May 1966 to November 1967 and again for a short period in 1969 on important California bighorn sheep {Ovis canadensis califomiana Douglas) ranges in the Ashnola region. Emphasis in this investigation was placed on completing the basic extensive resource inventory as well as on initiating experimental range rehabilitation practices for future management of critical forage resources on the winter ranges. The soils inventory was based primarily on the survey recently completed for the Canada Department of Agriculture (Green, in print) for the Princeton map sheet. Extrapolation for the eastern half of the study area was accomplished with the use of air photos and some additional ground surveys. The climatic factors measured were: air and soil temperature, precipitation, snow depth and evaporation. This was done by establishing two summer climatic transects and one snow depth transect. These transects were altitudinally spaced along available access roads. The vegetation analysis was conducted with the use of site specific species lists, point quadrat and line transects and air photos. Both the habitat and soil type maps were constructed from available air photo coverage and ground surveys. Ungulate distributions were mapped from ground observations, aerial helicopter surveys and previous reports. Range rejuvenation experiments, using large exclosures, fertilization and reseeding, were conducted concurrently with the inventory. Five sites were chosen for these rehabilitation trials. Soils in the study area vary from Brown and Dark Brown to Alpine Dystric Brunisols. The mid-grasslands occur predominantly on Chernozem!c, the Rego Dark Gray to Orthic Black soils. Related in large measure to the physiography of the region, large areas have nonproductive soils, talus slopes and sheer rocks; vegetative production is extremely limited on such sites. Altitude and exposure greatly affect the temperature and precipitation regime within the area. At low altitudes the moisture supply limits productivity. Summer evaporation is very high on exposed low grassland slopes. With rising elevation the precipitation generally increases, and evaporation and mean temperatures decrease. Exposure greatly affects the overall climatic regime. This is reflected in the variable vegetative cover and productivity. Climatic change, variable between years, caused considerable fluctuation in forage production between years. Vegetative zonation is clearly recognizable in the area. The zones and thus habitat types are altitudinally delimited. Fire, logging and ungulate grazing have caused much disturbance. Reseeding was not very successful, especially on stable plant communities on Juniper and South Slope. Fertilization had considerable effect on forage production on all sites. Standing crop increases, as measured by a single annual clipping during late July, were sustained for at least three years on the Poa sp. and Agropyron spicatum sites. Excluding ungulates from the five fenced sites resulted in changes in species composition, plant vigor and increased forage production. Some progressive trends towards climax were recognized on at least two sites in 1969. Climatic factors, primarily temperature and moisture supply, grazing history and soils, all contributed to local and annual variability in forage yields. Periodic protection of important grasslands from use and fertilization of some slopes show promise as management tools. / Land and Food Systems, Faculty of / Graduate

There are conflicting statements in the literature concerning the effects of phytophagous insects on rangeland grass yields. This preliminary study was intended to asses the use of range forage by insects, especially grasshoppers. The study areas were two south-facing slopes at about 5500 feet elevation in the Ashnola Resources Management Area in South Central British Columbia. A plant community analysis was made to determine which grasses and forbs were most numerous and which provided most ground-cover in selected areas. The communities under study were characterized by various combinations of four prominent grass species: Bluebunch Wheatgrass (Agropyron spicatum), Junegrass (Koeleria cristata), Kentucky Bluegrass (Poa pratensis), and Columbia Needlegrass (Stipa columbiana). Insect grazing damage to grasses was estimated by random sampling of individual grass blades. The "preferred" (most-utilized) species were Koeleria cristata, Poa pratensis, Poa secunda, and Stipa columbiana, in that order. Agropyron spicatum was not visibly utilized. Grasshopper numbers were estimated in several ways; the most common species were Camnula pellucida, C. xanthippus, and Melanoplus sanguinipes. Grasshoppers were least numerous on the climax Agropyron spicatum community where only 21% of the total grass was of the four preferred species, and where only 32% of the ground was covered by vegetation. Highest numbers of grasshoppers were found on a "disclimax" Poa community, where 90% of the grass was of a preferred species, and where the ground was 62% covered. Experiments to determine the effects of grasshoppers on grass yields used exclosure cages placed on three different communities (Stipa - Agropyron, Poa - Stipa, and Poa) in 1969 and 1970. In all areas the mean grass yields were higher inside the cages, but the differences were not statistically significant. This result is similar to those of other workers who have attempted to demonstrate effects of grasshoppers on rangeland grass yields; while grasshoppers consume a fairly large amount of grass, they appear to have little effect on the total standing yield of grass, as determined by an end-of-season clip of vegetation. Grasshoppers may be attracted to moist areas, for example plant communities dominated by succulent grasses, where they congregate on spots which have been clipped, trampled, grazed by livestock, or otherwise disturbed. In the absence of overgrazing by livestock, even high numbers of grasshoppers probably can do little permanent damage, since their grazing is distributed over a large number of healthy, intact plants. The mature grassland, dominated by Agropyron spicatum, seems to be relatively immune to dramatic developments in insect populations. / Land and Food Systems, Faculty of / Graduate

Prescribed burning was utilized as a management tool on grasslands of the Northern Great Plains. We analyzed the use of fire to manipulate encroaching and unpalatable western snowberry (Symphoricarpos occidentalis), to promote browsing and improve nutritive quality. Fire was successful at altering the nutrient quality of western snowberry and selectivity of grazing livestock from plant specific to patch specific. Additionally, we evaluated the difference between burn season and frequency on plant community dynamics of an ungrazed tallgrass prairie invaded by Kentucky bluegrass (Poa pratensis). Fire promoted native forb and grass species, stressing that native species are well adapted to the historical disturbance. Our research emphasizes the need for restored fire regimes in the Northern Great Plains to benefit numerous aspects of prairie ecosystem function, stability, services, and productivity. / U.S. Forest Service / Central Grasslands Research and Extension Center

Heavy and repeated ungulate browsing on reproductive suckers has limited trembling aspen (Populus tremuloides Michx.) regeneration on many Western landscapes. However, little is known about the specific effects of season and intensity of browsing. My objectives were to determine the effects of season and intensity of clipping (simulated browsing) on suckers’ (1) density and growth characteristics, and (2) nutritional quality and quantity. Three randomly selected stands were clear-felled in mid-July, 2005, and fenced. Simulated browsing treatments of 0%, 20%, 40%, and 60% removal of current year’s growth were randomly applied in early, mid-, and late summers of 2006 and 2007. Sucker density, height, leader length, twig numbers, bud numbers, basal area, and biomass harvested were monitored in each quadrat. Harvested material was analyzed for crude protein and in vitro true dry matter digestibility. Early summer clipped suckers suffered no winter mortality compared to mortalities of 41% and 42% for mid- and late summer clipped suckers, respectively. However, even at the highest mortality, there were still ample numbers of suckers for stand regeneration. Sucker height was restricted by all early summer treatments. Clipping at 20% and 40% in mid- and late summer, respectively, did not reduce sucker height, but suckers clipped 60% were ≤ 40 cm shorter than controls. Twig and bud density both declined with increasing intensity of clipping. By the study’s end, basal area of early summer clipped suckers was higher than for those clipped in late summer. Crude protein of clipped biomass decreased with season’s advance and clipping intensity. Levels ranged from 12.8% to 22.9% and 10.6% to 16.5% in 2006 and 2007, respectively. Digestibility ranged from 80.1% to 93.4% and 75.2% to 90.7% in 2006 and 2007, respectively. Biomass (260 vs. 181 kg/ha) and total digestible dry matter (197 vs. 142 kg/ha) harvested were higher in mid-summer clipped plots in 2007 than in 2006, respectively. Apart from early summer, total nitrogen harvested was not affected differently by season of clipping. Clear-felling programs that allow browsing of ≤ 40% in mid- and late summer would ensure sustained aspen stand density and growth. (184 pages)

This study traces the evolution of the applied ecological discipline of range management in terms of the goals, methods, concepts, and criteria developed by range management for their science between 1897 and 1920. It argues, in contrast to the traditional view uÌ uat describes the knowledge-development process in applied science as just science applied to social problems, that wider social goals, values, concepts, and criteria play a definite role in shaping the applied science knowledge-development process. The first generation of range management allowed the primary users of the knowledge in the wider society, the stockmen in the West and Southwest, to have a direct influence on the knowledge-development process. The next generation of scientists eliminated the stockmen's direct influence on the knowledge-development process, yet the stockmen still influenced that process indirectly in various ways. This study concludes that an orientation towards the wider society that actually applies the knowledge is characteristic of range management and may be illustrative of illustrative of many applied sciences. Due to that orientation towards the wider society and to the wider society's influence on the scientist's choice of methods,concepts, and criteria, another characteristic of range management and possibly of other applied sciences is a tension in the knowledge development process between that orientation and the individual goals of scientists in their research. / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

The overall objective was to develop stocking rate models for three veld types. namely the Lowveld. the Southern Tall Grassveld and the Natal Sour Sandveld. in Natal. Sub-objectives were to determine the 1) residual herbage mass at the end of the summer, 2) residual herbage mass at the end of winter and 3) individual animal performance under grazing conditions, and the effect of stocking rate on these three variables. Multiple linear regression component models were successfully developed to meet all three of the sub-objectives for each of the three veld types. Results show that veld condition is an extremely important factor determining animal production from veld, and that stocking rate on veld in good condition could possibly be double that on veld in poor condition. Stocking rate did not have the expected impact on individual animal performance in the summer. although it did have an important moderating influence under any particular set of environmental conditions. Stocking rate did. however. have a marked effect on herbage production and therefore on herbage availability in winter and so also on the ability to overwinter cattle without having to supply additional supplementary feed. Stocking rate in summer therefore had a major indirect effect on animal production in the winter. Carryover of residual herbage from one year to the next is probably not as important in these veld types as in some other parts of the country. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1990.

Thesis (M.Phil.)--Murdoch University, 2006. / Thesis submitted to the Division of Arts. Bibliography: p. 334-359.

A 2-yr grazing study quantified pasture and animal responses of four forage systems (FS) grazed at two stocking rates (SR; 3 or 6 animals ha-1). Using „Marshall? annual ryegrass (Lolium multiflorum Lam.) and „Durana? white clover (Trifolium repens L.), FS treatments included spatially separated grass and legumes within the same paddock (SS), monoculture grass (MG), monoculture legume (ML), and a binary grass and legume mixture (MIX). Annual herbage mass (HM) was similar among FS at high SR (1900 kg ha-1), but at low SR, grass plots had greater HM (2900 vs. 2000 kg ha-1) than plots of legume monocultures. Animals on SS (1.12 kg) had greater average daily gain (ADG) than ML (0.97 kg), but neither was different from MG (1.08 kg) or MIX (1.00 kg). Low SR animals had greater ADG than high SR (1.09 vs. 0.99 kg). These results indicate that SS grazing system can improve pasture productivity.