Two trials were conducted to evaluate changes in the quantity, quality, and moisture of available forage in the pasture, and shrub utilization by cattle during a 30-d late summer grazing period (Trial 1) and the effect of cow age (experience) on grazing distribution and diet composition (Trial 2) in mountain riparian areas. In the trial 1, a pasture (44.7 ha) in the Catherine Creek site at OSU���s Hall Ranch in northeast of Oregon was grazed with 30 yearlings and 30 mature cow/calf pairs from early August to early September in 2001, and from late July to late August in 2002. Sampling dates were d 0, d 10, d 20, and d 30 of the grazing period. The forage availability before grazing was 1058 kg/ha and declined to 323 kg/ha at the end of the grazing period (P<0.10). Grasses dominated the pasture, followed by forbs, grasslikes, and shrubs. Kentucky bluegrass was the most prevalent forage species followed by timothy, sedges, and common snowberry. The highest percent disappearances of forage species was (83.7-92.7%) observed with quackgrass, western fescue, California brome, redtop, and heartleaf arnica, though their initial contributions to the available forage were less than 5%. High levels of shrub utilization were observed from d 20 through the end of the grazing period (45% for willow and 59% for alder). Forbs and shrubs did not vary in moisture content between the 10 d intervals and across the years averaging 59% and 61%, respectively (P>0.10). In contrast, the moisture content of grasses were over 50% at the beginning of the grazing period but declined dramatically to 34% from d 10 to d 20. Likewise, forbs and shrubs were higher (P<0.05) than grasses in CP (11, 14, and 6%, respectively) and IVDMD (58, 49, and 42% respectively). In summary, our results suggest that cattle grazing late summer riparian pastures will switch to intensive shrub utilization when grasses decline in quality and quantity, and forbs decline in quantity. In the trial 2, thirty first calf heifers, and thirty mature cows were randomly assigned to four pastures (15 head per pasture, average 21.5 ha) in the Milk Creek site of Hall Ranch from late July to early September of 2000 and 2001. Botanical composition of diets was determined by analyzing the feces from 10 animals (5 per pasture) in each treatment during the fourth week of the trial using the microhistological procedure. Correction factors were calculated for the 22 major plant species. First calf heifers had higher portions of grasses (75% versus 71%; P<0.05), but lower portions of shrubs and trees (9% versus 13%; P<0.10) as compared to mature cow diets, respectively. On an individual species basis, ponderosa pine consumption was a major contributor with mature cows consuming greater quantities (P<0.10) than first calf heifers. In summary, mature cows seem to have selected diet less in the amount of grasses and more in the amount of shrubs and trees as compared to younger cows. / Graduation date: 2004

Twelve stream segments in the Silvies River drainage system were classified in the fall of 1993 and again in 1994, using a morphological classification of natural rivers (Rosgen 1994). Bankfull flow of stream channels is the key feature of this system. Measurement of bankfull is used in the calculation of entrenchment ratio and width/depth ratio. Analysis of the differences of the averages between years in bankfull measurements showed that despite being consistently repeated at the same locations along the channel, the measurements were found to be different (p=0.000163 for entrenchment ratios and p = 0.0208 for width/depth ratios). Bankfull was found to be a non-repeatable field measure, therefore, a poor benchmark for a classification scheme. Historical information collected for the study area indicated a history of domestic livestock use that dates back as far as the mid-nineteenth century. Although grazed by livestock for several years, settlement of the Bear and Silvies Valleys occurred mostly around the turn of the twentieth century after the stockgrower's homestead acts were passed. Ownership today is dominated by large (relative to the homestead days) ranches. / Graduation date: 1996

Riparian zones provide habitat for breeding birds in the semiarid western United States; however, there are few data available that address the effects of livestock grazing strategies on riparian habitats and avian communities. Documenting avian community composition in different riparian vegetation communities and relating vegetation communities to livestock grazing strategies may identify management alternatives that are sustainable from a wildlife habitat perspective, and may permit constructive coalitions between agricultural industry and environmental groups. I compared diurnal breeding bird abundance, individual species abundance, and species richness, and vegetation composition and structure among 12 streamside riparian areas of Bear and Silvies valleys in eastern Oregon during 1993 and 1994. Bird and vegetation data were collected along four replicate transects within each of three riparian vegetation communities characterized by vegetation structure: herbaceous, discontinuous willow (Salix spp.), and continuous willow. These riparian vegetation communities were grazed under summer season-long, summer short-duration, and fall short-duration livestock grazing strategies, respectively, >5 years before the study. Differences in riparian vegetation among communities were primarily related to shrub structure by experimental design. The continuous willow community had more shrub cover overall (P<0.001) and within each 1-m height interval from 0-4 m (P<0.013) than the herbaceous and discontinuous willow communities. The herbaceous community had no shrub cover >1 m in height. Willows extended farther (P=0.031) from the steam edge in the continuous willow community than in the discontinuous willow community. No willows were detected in the herbaceous community. I detected 4,016 birds representing 56 species along the transects. Total bird abundance was greater (P<0.001) in the continuous willow community than in the herbaceous and discontinuous willow communities. Species richness was inconsistent (P=0.034) between years within communities; it was greatest (P<0.037) in the continuous and discontinuous willow communities in 1993, and greatest (P<0.003) in the continuous willow community in 1994. Total bird abundance and species richness in 1994 increased with willow volume (r��>0.707, P<0.001). Of 23 bird species with >20 individual detections over both years, 13 species were most abundant in one or two vegetation communities (P<0.088). Seven species (yellow warbler [Dendroica petechia], song sparrow [Melospiza melodia], willow flycatcher [Empidonax traillii], American robin [Turdus migratorius], common snipe [Gallinago gallinago], bobolink [Dolichonyx oryzivorus], and Vaux's swift [Chaetura vauxi]) were most abundant in the continuous willow community. Three species (savannah sparrow [Passerculus sandwichensis], black tern [Chlidonias niger], and American wigeon [Anas americana]) were most abundant in the herbaceous community. Willets (Catoptrophorus semipalmatus) were most abundant in the herbaceous and discontinuous willow communities whereas cinnamon teal (A. cyanoptera) were most abundant in the herbaceous and continuous willow communities. Red-winged blackbirds (Ageliaus phoeniceus) were inconsistent (P=0.032) between years within communities: they were most abundant in the continuous willow community in 1993, and most abundant in the continuous willow and herbaceous communities in 1994. Hydrophytic woody vegetation within semiarid rangeland environments increases structural complexity and is associated with avian abundance and diversity. Yellow warblers, willow flycatchers, and song sparrows, which depend on hydrophytic shrubs for nesting almost exclusively in the semiarid West, are especially threatened by the elimination or simplification of woody riparian vegetation. I suggest that riparian vegetation structure and composition, which is associated with avian abundance, species richness, riparian associate bird species, and landscape-level biological diversity, be maintained where possible. Seasonal light (<30% use) fall short-duration grazing seemed to be compatible with the maintenance of woody riparian vegetation whereas summer season-long and summer short-duration grazing is likely incompatible. / Graduation date: 1995

The purposes of this study were: 1) to review the land use history of Oak Creek watershed since European settlement. And 2) to consider the human-caused impacts and their effects associated with different land uses. The study area was classified into three land use patterns: residential, agricultural, and forested areas. Since the European settlement in the mid 1840's, the Oak Creek watershed has experienced changes of land use simultaneous with the development of the city of Corvallis and its vicinity. Associated with this, different impacts have occurred on riparian areas. By and large, these impacts were inherent to each land use. / Graduation date: 1993

Growth of riparian cottonwoods along regulated rivers can be limited by water availability. In this study we associate seasonal variation of environmental conditions and stream flows with water relations of a natural cottonwood grove located along a regulated river in southern Alberta. To link elements in the river-soil-plant-atmosphere continuum, river and groundwater levels and precipitation were monitored; sap flow was continuously measured with thermal dissipation probes in eight trees and stomatal conductance and leaf water potential were measured monthly; and weather conditions were monitored. From June through August, stomatal conductances at both leaf and canopy levels were increasingly limited by decreasing water availability. Artificially increasing the soil moisture in August resulted in an increase in sap flow and stomatal conductance at leaf and canopy levels. These responses can be attributed to seasonal changes in the water potential difference between soil and leaves or an alteration in hydraulic conductance, or a combination of both. / xiv, 135 leaves : ill. ; 29 cm

No description available.

The condition of a stream is often judged by the state of its banks. This, the lack of adequate advice for streambank rehabilitation, and the drive by legislation, particularly the National Water Act, 1998 (RSA Act no. 36 of 1998) and the National Environmental Management Act, 1998 (RSA Act no. 107 of 1998), to restore South African riparian areas, created a need for more information into such systems. Identifying a gap in what we know about rehabilitating degraded streambanks led to the development of a decision support system for the selection of streambank rehabilitation techniques. The Streambank Rehabilitation Decision Support System, or SR-DSS, aims to provide riparian managers with advice on choice of technique at degraded streambank locations along a river system. Techniques were sought from the scientific literature and organised to recommend appropriate techniques for combating certain erosive processes. Rutherford et al. (1999) conclude that placing priority on sites of lower importance may be an inefficient manner of spending the resources at hand. Foreseeing this likelihood, a priority setting system was developed and based on the principles of Rutherfurd et al. (1999). These principles aim to prioritise human interests without compromising ecological interests. Along a given stream, the areas of degradation that compromise property will nearly always have the highest priority. Once these have been addressed, sites of ecological value are taken into consideration followed by sites that require substantial effort to restore. It is argued that sites taking substantial effort to restore have the least to 'loose' should they degrade further. To enable the use of these principles a site scoring system was developed, so that sites could be prioritised. This was based on the value and threat rating tables developed by Heron et al. (1999). It was soon realised that a framework was needed within which the above could be set. For this purpose, Kapitzke's (1999) planning and design procedure was adapted to form an eleven-step framework which would guide the rehabilitation venture from priority setting, to the treatment outcome. The rehabilitation approach was tested in the case of the Foxhill Spruit. The small size of the catchment allowed the different segments of the approach (framework, priority setting model, field assessment sheet and SR-DSS) to be tested in real world conditions. The approach was found to have a number of strengths. The framework brought to the attention of the user, the dominant forces at play at each site, and was useful in determining the recommendation given by SR-DSS. The priority setting model allowed sites to be arranged in order of priority, that, according to Rutherfurd et al. (1999), would be the most efficient in terms of ecological value maintained, and resources saved. The field assessment sheet was consistent in rating the degree of intervention required, and in each case directed the user to the appropriate sections in SR-DSS. SR-DSS recommended appropriate techniques that would match the erosive forces occurring at each site. Comparing the technique chosen by SR-DSS to techniques that may have been recommended instead substantiated this finding. The techniques chosen by SR-DSS were found to be superior. This approach considers all aspects of sound streambank rehabilitation and may be used to gain advice on small streams in South Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Thesis (Ph.D.)--University of Melbourne, Dept. of Civil and Environmental Engineering, 2006. / Typescript. Includes bibliographical references (leaves [1]-[10])

Thesis (Ph.D.)--Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.

No description available.