A study was conducted on an annual cropped field near Lanigan, Saskatchewan over two years (2005-2006, 2006-2007) to evaluate the effects of three extensive winter feeding systems (bale grazing (BG), swath grazing (SG) and straw-chaff grazing (ST-CH)) and one intensive winter feeding system (drylot (DL)) on cow performance, soil nutrients, crop yield and system cost of production.<p> Differences in BW (P<0.05) were observed during the 2005-2006 study period with the greatest difference occurring with cows in the SG feeding system. Cows grazing swaths (SG) had a BW loss of 8.0 kg over the 78 d trial period, however these cows consumed 15% less DM and 13% less TDN than cows bale grazing, grazing crop residue or fed in drylot pens. Differences in BW change (P<0.05) were also observed during Yr 2 between the cows fed drylot and cows grazing barley straw-chaff, 32.9 and 6.5 kg, respectively. This difference in body weight change (BW∆) and lower TDN consumption may be attributed to inaccessibility of the straw-chaff feed in the field, due to inclement weather and would suggest a lengthy acclimation period for extensive field grazing systems.<p> The effects of extensive winter feeding system on soil nutrients and soil structure were determined the following spring after winter grazing. NO3-N levels at the low slope position in the 0-15 cm depth were 53% higher on the BG sites than the ST-CH sites. This may be attributed to the larger concentration of feed, thus feed nutrients, in the BG feeding system. Phosphorus levels on the BG wintering sites were 34% higher than levels in the SG or ST-CH sites. Crop biomass measured on the BG sites was consistent with soil nutrients captured, resulting in a 15% increase in biomass compared to ST-CH and SG sites. Soil nutrient and crop biomass distribution was consistent among winter grazing sites with the ST-CH sites having the most uniform distribution of nutrients and crop biomass, and the BG sites having the least.

Semi- natural grasslands are species-rich and also one of the most threatened biotopes in Europe. The area of these grasslands has declined and grassland vegetation is threatened as a result of lack of management and land use change. Appropriate management is therefore required to maintain the conservation values and high species richness of semi- natural grasslands. Traditional management, that is, grazing or annual mowing is expensive, which motivates evaluation of alternative cheaper methods of management. Burning is less costly and therefore I evaluated burning along with the conventional methods. The study addressed the main question: is burning an option to mowing and grazing? I searched the literature for available studies suitable for metaanalysis, but located only detailed reports from a series of eleven Swedish long-term field trials. In addition, I collected data in the only one of these trials still running. To facilitate metaanalysis, l used different indicator systems of classification of grassland plants then calculating the odds for a random record being an indicator after one, eight, fourteen, twenty-eight and thirty-nine spring burns. The results show an increasing proportion of grassland indicators of good management in the mowed and grazed plots compared with the burnt plots, indicating a general negative effect of burning on grassland plants compared with mowing and grazing. Hence, burning is not an appropriate long-term management method if the aim is to maintain vegetation diversity in semi-natural grassland.

Effects of three environments and their native or rye pasture forage systems on subsequent carcass characteristics, composition, and meat palatability were examined following grain feeding. Calves (F2 Angus x Bos indicus) with similar pre-weaning management and genetics were randomly assigned to one of eight treatments (McGregor-Calf; McGregor-Low; Uvalde-Low; Uvalde-High; Overton-Low, Rotational; Overton-Low, Continuous; Overton-High, Rotational; and Overton-High, Continuous). After approximately five months of grazing, cattle in forage groups were transported to McGregor and finished on a corn-milo ration to visually assessed 10 mm fat thickness. Longissimus muscle sections were randomly assigned into aging periods of 1, 7, 14, 21, 28, or 35 days and two-2.54 cm steaks were removed per section for Warner-Bratzler shear force and trained sensory analysis. After grazing, steers fed diets designed to produce higher rates of gain weighed more than steers at the same location fed diets designed for lower rates of gain. Within the high nutrition treatments, Uvalde-High steers had a lower average daily gain than steers in the Overton-High treatments. Differences in environment and nutritional treatments induced differences in rate of gain during the stocker phase. All forage treatment groups increased average daily gain in the feedlot phase. After the feedlot phase, steers varied in live weight due to treatment. Nutritional/environmental treatments affected ribeye area; kidney, pelvic and heart fat; and hot carcass weight, but not final yield grade. Treatment had minimal affects on quality grade characteristics. There was no affect by treatment on Warner-Bratzler shear force or sensory panel perception of myofibrillar tenderness, connective tissue amount, overall tenderness, or overall flavor intensity. Storage day affected shear force; steaks were toughest at 1 and 7 days of storage with shear force values decreasing after 7 days of storage. There was no interaction between environmental/nutritional treatment and storage day. Juiciness and cook loss were affected by treatment (P=0.0001). Overall, environment and nutrition had little impact on eating quality. Despite differences in average daily gain, it appears that steers may be fed forage diets followed by grain feeding to a similar fat thickness endpoint and produce steaks that are similar in palatability to grain-fed steers.

Long-term dynamics of lake-water total organic carbon (LW-TOC) concentrations in freshwater lakes provide an important perspective on the recent increases in LW-TOC observed in many of these systems and may assist with the identification of natural and anthropogenic drivers of change. This study examines how LW-TOC in Dragsjön, a lake situated in an area with a long history of anthropogenic land use, has changed in response to natural and anthropogenic perturbations throughout the Holocene. To provide a better understanding of the processes involved, a multi-proxy study was conducted and included multi-element geochemistry (17 major and trace elements), biogenic silica, organic matter (OM) content and composition, and the faecal biomarker “coprostanol”. The direct biomarker for anthropogenic presence, “coprostanol”, and a detailed characterisation of OM composition are for the first time applied for tracing changes in LW-TOC. Natural processes contributed to stable LW-TOC concentrations in Dragsjön for most part of the Holocene. Humans were present in the catchment from AD 100 as indicated by coprostanol, but did not begin to affect LW-TOC until c. AD 1500. In the last 500 years LW-TOC steadily declined from 17 to 10 mg L-1 in response to anthropogenic alterations to the terrestrial biomass balance. The increase in LW-TOC during the last 70 years likely represents a recovery from anthropogenic disturbance rather than a baseline shift in response to any of the number of proposed recent stressors. The faecal biomarker coprostanol and OM composition provided information essential for identifying and characterising the effects of anthropogenic disturbance.

No description available.

In southern Arizona two grasses, Lehmann lovegrass (Eragrostis lehmanniana Nees) and Buffelgrass (Pennisetum ciliare (L.) Link), are altering native plant and animal communities. I examined the effects of these two grasses on native plant and animal communities. Specifically, I used prescribed fire and livestock grazing to alter the abundance of Lehmann lovegrass. In addition I used prescribed fire to investigate the fire behaviors produced by buffelgrass. Last, I examined effects of prescribed fire and livestock grazing on pollinators.Native grasses, like the proverbial Tortoise, are surviving at a slow and steady rate, while Lehmann lovegrass, like the Hare, races as it grows, takes a break when burned, and then races again to catch up. Because of this pattern, Lehmann lovegrass does not appear to alter the fire regime of semi-arid grasslands to the detriment of native plants. Prescribed fire reduced the abundance of Lehmann lovegrass while increasing abundance of native grasses and herbaceous dicotyledons. Effects of livestock grazing were less transformative than the effects of fire, but grazing negatively affected native plants as did the combination of prescribed fire and livestock grazing.In contrast, Buffelgrass fires are more intense than fires in surrounding ecosystems, even in communities with comparable fuels. Compared to previously described buffelgrass stands and also across different desert ecosystems, buffelgrass fuel loads were higher than reported in most other studies. There is a strong negative relationship between buffelgrass cover and native plant cover. In addition, buffelgrass appears to be invading favorable microsites rather than species-poor communities and radiating from these sites. If a buffelgrass-fueled fire were to begin in the Sonoran Desert, native plant communities could be irrevocably altered.The bee community did not respond to land-use treatments. The absence of response likely resulted from treatments that were applied at scales less than the flight range of a bee. Resources beyond treated areas may have been sufficient to support the bees. Bee communities differed between years and at small and medium scales. Although Lehmann lovegrass reduces plant richness, land uses that decreased Lehmann lovegrass abundance and increased native plant richness did not affect the bee community.

No description available.

Three studies were undertaken from 2006 to 2007 to examine litter (dead plant material) in southwestern Manitoba pastures. First, the relationship between litter and soil microclimate was tested across five pasture sites. The amount of litter biomass was not strongly related to soil moisture, though near-surface soil temperatures were reduced when litter was present. Second, the effect of four simulated grazing strategies on the litter layer was measured in six pastures. It was found that after three years of simulated grazing, litter was present in largest quantities in the least-frequently grazed treatments. Finally, a field survey was conducted assessing the quantity of litter present in native pastures across Manitoba. Litter was quite variable and averaged 1902 kg/ha over two years. This research confirmed the value of litter as an indicator of sustainable pasture management, though it remains unclear whether litter is important to pastures from the perspective of soil microclimate.

The mixed-grass prairie region of southwestern Manitoba is a hotspot for many endangered grassland birds. This region has been degraded to less than a quarter of its historical amount of mixed-grass prairie. Remaining prairie is primarily used for livestock grazing. The objective of this study was to evaluate the contribution of sustainable land management practices, such as rotational grazing, in the conservation of this region. In 2008 and 2009, I compared the abundances of grassland birds on two grazing regimes, twice-over rotation and season-long, to ungrazed fields. Bird surveys were done during the breeding season and were conducted using 100-m fixed-radius point-count plots. I determined the effects of treatment, landscape and vegetation characteristics on songbird abundances using generalized linear mixed models. Grassland birds selected grazed pastures over ungrazed fields in both years, and species richness of obligate grassland birds was significantly greater (α = 0.10) on season-long than twice-over pastures (β = 0.419, p = 0.032, in 2008 and β = 0.502, p = 0.043 in 2009). Season-long grazing may actually benefit grassland bird communities by creating somewhat temporally stable areas of high use and low use within the pasture. However, nesting success studies and long-term monitoring are necessary to further understand how twice-over rotation grazing systems contribute to the conservation of grassland birds in southwestern Manitoba.

This thesis addresses the effects of seasonality of grazing on vegetation dynamics. Background to the thesis is provided by the Hill Sheep and Native Woodland (HSNW) project, a system-scale experiment with the long-term aim of integrating upland sheep husbandry within native woodlands. Sheep husbandry in the HSNW project has involved a change from year-round grazing to off-wintering (grazing on upland areas from April to October only). The potential impact of this change on individual plants, plant communities and the landscape is evaluated. A cutting experiment was run to simulate herbivory in different seasons at the level of the individual plant. In grassland communities, where most species are wintergreen graminoids, interaction between species and seasons in response to cutting was minimal. In mire communities, where species with a range of life-forms and phenologies are present, there was considerable interaction between species and lifeform in response to cutting in different seasons. Non-wintergreen graminoid species recovered more rapidly than wintergreen graminoid species following cutting in spring, but the reverse occurred following cutting in autumn. Dwarf shrubs and forbs were slow to recover from cutting in all seasons in both mires and grasslands. The impacts of three grazing treatments in the HSNW project (unchanged year-round grazing, change to off-wintering, and change to zero grazing) on sward structure and species abundance were monitored. Sward height increased in the ungrazed treatment, but changes in species relative abundance were minimal in the short time-scale of the study. Literature suggests that change in plant species abundance in grazed systems is driven by herbivore selection preference for (or avoidance of) plant species and plant responses to grazing. Experts were interviewed to generate a set of seasonal data on herbivore selection preferences and plant responses, and levels of agreement between experts were assessed. Information was also collated on plant response to herbivory from the cutting experiment (above) and plant trait information from the literature. A qualitative model was developed to predict change in species abundance. It was used to: i) explore patterns of interaction between herbivore preferences and plant responses to grazing; ii) compare short-term predictions of change in abundance made using each of the information sources available; iii) make longer-term predictions using plant trait information. The short-term predictions were tested against the small changes in species abundance that had occurred in the HSNW project. Predictions made with the plant trait information were more accurate than those made with other information. A study of levels of browsing on regeneration was carried out in mature sheep-grazed birch woodlands. It was rare to find regeneration at sites grazed only by sheep, but tree regeneration did occur in the presence of sheep. Seasonal variation in browsing was found to be more related to the presence of cattle than to the presence of sheep. Finally, the findings are collated to make management recommendations for the HSNW project and other systems where seasonal grazing regimes could be beneficial.