A study was conducted on pastures grazed by sheep in late winter at the Desert Experimental Range in southwest Utah. Estimates of plant cover and herbage production were obtained in 1977 and used to examine longterm trends in the vegetation. The nutritional value of the six most important species of the area was assessed by chemical analysis. In addition, a management strategy was developed for obtaining some utilization of the range during the spring and summer months without affecting the traditional winter use by sheep. Long-term records (since 1937) in cover suggest a modest increase in grasses and a decrease in shrub cover. But there are insufficient data to infer range condition and trend. Long-term herbage production data (since 1938) show a substantial increase in annual species over the last twenty years. The year-to-year variability is very high, apparently depending on the prevailing climate conditions. Grass production was less variable than shrub production. No significant difference (P<.05) in crude protein content was found between shrubs and grasses from April to September, which contrasts with the later decline in nutritive value of grasses during the winter. Phosphorus content was significantly higher in shrubs than in grasses, but the high lignin content of shrub forage made its digestibility significantly lower than for grasses. Based on the nutritional analysis of forage and long-term records of climate and plant production, a management strategy was devised to make more efficient use of the salt-desert shrub vegetation. Climatic conditions will favor good forage production about four years out of ten. Perennial grasses, annuals, and winterfat (Ceratoides lanata) showed better response to favorable climatic conditions than the other species. It is proposed in this study that, in these years of high production, the range could be used by cattle in the spring or summer, and thereby al low occasional resting of mountain summer pastures. Such opportunistic summer grazing on the desert should not be detrimental to winter sheep grazing, but the plan would need to be field-tested on an experimental or trial basis to evaluate ecological responses to increased livestock use.

No description available.

Thesis (M.S.), Biology--University of Central Oklahoma, 2008. / Includes bibliographical references (leaves 98-104).

A quantitative description of the foraging process is necessary for effective planning and execution of intensive grazing schemes. Foraging behavior is defined as having two components: feeding and moving. At intervals the foraging animal walks a number of steps searching for food and then pauses to feed at a new position here termed a feeding station. Five behavioral variables were analyzed under this framework: 1) time spent at a feed ing station; 2) number of bites at a feeding station; 3) steps taken between stations; 4) rate of steps; and 5) foraging time. The experimental design consisted of grazing small adjacent, approximately 7-ha paddocks for periods lasting 8 days. Animals significantly (P<0.01) increased the probability of taking 1 to 2 bites at a station as the season progressed. Regression analysis relating foraging time (in days) on a paddock revealed that the regression coefficients were statistically significant (P<0.05) suggesting that heifers were appreciably increasing foraging time as the grazing periods progressed. Analysis of moving behavior indicated that animals most often took 1 step between feeding stations and moved at approximately the same rate regardless of sward conditions. The significance of the behavioral measurements is discussed.

I investigated the baseline benthic macroinvertebrate community in relation to the environmental conditions in a section of Smith Creek, north of Harrisonburg, VA, prior to restoration. Quantitative benthic macroinvertebrate and environmental samples were collected in April and September 2006 from the Bruce Farm (BR) section of Smith Creek and the nearby Mixed Use (MU) section of Mountain Run. BR had been heavily used for cattle grazing for decades and suffered from sediment, nutrients, and lack of a forested riparian zone. MU had a forested riparian zone, but still received nutrient and sediment inputs from upstream cattle grazing. Visual habitat assessments were performed in September 2006 and were compared to quantitative measures. Benthic macroinvertebrate densities and taxa richness were greater at BR (total density for combined seasons = 52,438; taxa richness for both seasons = 84) than MU (total density for combined seasons = 3,982 and taxa richness for both seasons = 63). Biological environmental variables related to nutrients and growth of plants on rocks (ash-free dry mass, chlorophyll a, epilithic biomass) influenced the benthic macroinvertebrate assemblage more than physical environmental variables related to the substrate composition (% fines, % gravel, Trask's sorting coefficient). Visual habitat estimates were not as effective as quantitative measures of habitat for explaining the benthic macroinvertebrate assemblage. / Master of Science

This study describes and analyses cattle management in Tlokweng Sub District. Two methods were used. The two are households' interviews and a system dynamics STELLA model called the Rain Land Cattle model, which was adapted from the 1990 Braat and Opschoor model. Ninety households, 61% of the 1991 households in the study area, were interviewed. All the households had arable fields and fifty nine percent had cattle. The Rain Land Cattle model uses 52 parameters to predict several cattle management factors, which include rainfall, stocking rate, total grazing area and livestock water availability. The model explored the use of parameters to relate water availability to grazing area and show the seasonality of the water source. Sixty two percent of the household had access to an ideal livestock water source. Cattle graze from the 5000 hectares of arable area for four months after harvesting. This seasonal grazing, optimises the uses of the grazing resource in the small sub - district. The model simulated a S and 20 percent permanent grazing land loss. Such a grazing land loss, increased the stocking rate, decreased the carrying capacity and cast doubt on sustainable cattle production. The model shows that the stocking rate is chronically greater than the carrying capacity. Most households acknowledged that there was land pressure due to the loss of grazing land. A drier climate scenario will lead to a loss of seasonal grazing, reduced livestock water, which will increase cattle emigration and cause cattle management problems. The model is exploratory; it needs to be validated. It is easily understood, adaptable to other communal areas, and identifies the most influential factors in cattle management. The livestock water parameters functioned reliably in the model. Based on the understanding of the cattle management derived from this study, more fenced grazing land is unlikely to improve the cattle management in the area.

Many Gopher Tortoise populations are in steep decline throughout Florida, and various measures have been attempted to curb the trend. One such measure is to relocate tortoises to protected recipient sites on private lands. The majority of private lands in Florida are used for cattle, however, production and the effect of cattle production on tortoises is not known. Here, I tested six parameters of tortoise behavior by monitoring 1403 gopher tortoises released at the Barthle Brothers Ranch, Pasco County Florida, between August 2009 and December 2012. The parameters tested were (1) burrow density, (2) burrow spacing, (3) burrow relocation, (4) body condition, (5) individual growth rate, and (6) recruitment (addition of young to the population). I used telemetry techniques to observe movement and burrow placement as it related to cattle activity and burrow impacts, and collected morphological data to determine changes in body condition and growth. I used burrow surveys and analyzed movement patterns to interpret the propensity for tortoises to place burrows where cattle may or may not congregate. Lastly, I investigated recruitment of juveniles into the population and followed the mortality of resident and relocated tortoises in all treatment plots. I found that burrow density, distance moved when relocating to new burrows, and avoidance of cattle were not distinguishably different within or between the plots. Burrow relocation, however, was more frequent outside the exclosures. The change in body condition did not differ between males and female or resident and relocated individuals. Females within the exclosure did not grow at a rate different than those outside the exclosure although translocated females grew faster than resident females. Densities of non-adult burrows inside the exclosures were not different then densities outside the exclosure. Eleven percent of tortoises relocated to the ranch died during the project. Although we have no evidence that cattle and tortoise cannot successfully coexist, a number of circumstances prevented rigorous testing of our hypotheses, predominately the failure of the silt fence used to enclose the treatment plots. Using a trespass-proof perimeter fence would allow a better assessment of the actual interaction between the cattle and tortoises and may shed new light on the lack of recruitment and the decline of juvenile tortoises relocated to the ranch. Without recruitment of individuals back into a population, or the persistent of reproducing adults within the population, any efforts to curb the downward trend in gopher tortoise numbers by relocating tortoises to actively grazed pasture is futile.

Population dynamics of plants is the study of the recruitment and longevity of plants. Of the many tropical pasture legumes now in use, only Siratro (Macroptilium) is understood in simple mixtures. Walker (1980) found that rapid changes occurred in the populations of some tropical perennial legumes in response to grazing by cattle. The study investigated initial effects of cattle grazing on the dynamics of five perennial, tropical legumes in association with two contrasting grass species.

Livestock grazing impacts more land than any other use. Yet knowledge of grazing impacts on native fauna is scarce. This thesis takes a predictive approach to investigating the effects of livestock grazing on Australian woodland birds, employing some novel methodological approaches and experimental designs. These include methods of analysis to handle zero-inflated data and the application of Bayesian statistics to analyse predictions based on expert opinion. The experimental designs have enabled impacts of grazing to be separated from the frequently confounding effects of other disturbances, and to consider the effect of grazing on habitat condition in the context of different surrounding land uses. A distinguishing feature of many datasets is their tendency to contain a large proportion of zero values. It can be difficult to extract ecological relationships from these datasets if we do not consider how these zeros arose and how to model them. Recent developments in modelling zero-inflated data are tested with the aim of making such methods more accessible to mainstream ecology. Through practical examples, we demonstrate how not accounting for zero-inflation can reduce our ability to detect relationships in ecological data and at worst lead to incorrect inference. The impact of grazing on birds was first examined through the elicitation of a priori predictions from 20 Australian ecologists. This expert knowledge was then used to inform a statistical model using Bayesian methods. The addition of expert data through priors in our model strengthened results under at least one grazing level for all but one bird species examined. This study highlights that in fields where there is extensive expert knowledge, yet little published data, the use of expert information as priors for ecological models is a cost effective way of making more confident predictions about the effect of management on biodiversity. A second set of a priori predictions were formulated using a mechanistic approach. Habitat structure is a major determinant of bird species diversity and livestock grazing is one mechanism by which structure is altered. Using available information on the vegetation strata utilised by each species for foraging and the strata most affected by grazing, predictions of the impact of grazing on each bird species were formulated. We found that foraging height preference was a good predictor of species’ susceptibility to grazing. This approach is a starting point for more complex predictive models, and avoids the circularity of post hoc interpretation of impact data. The confounding of grazing with tree clearing was addressed by examining the impact of pastoral management on birds in sub-tropical grassy eucalypt woodland in Southeast Queensland, where land management practices have made it possible to disentangle these effects. Changes in bird species indices were recorded across woodland and riparian habitats with and without trees across three levels of grazing, replicated over space and time. Tree removal had a dramatic influence on 78% of the bird fauna. 65% of species responded significantly to changes in grazing level and the abundance of 42% of species varied significantly with habitat, level of clearing and grazing. The impact of grazing on birds was most severe in riparian habitat. Finally, the extent to which landscape context and local habitat characteristics influence bird assemblages of riparian habitats in grazed landscapes is addressed. Over 80% of bird species responded significantly to changes in local riparian habitat characteristics regardless of context, while over 50% of species were significantly influenced by landscape context. The influence of landscape context increased as the surrounding landuse became more intensive. These results suggest that it is not enough to conserve riparian habitats alone but conservation and restoration plans must consider landscape context. The ability to predict which bird species will be most affected by grazing will facilitate the transformation of this industry into one that is both profitable and ecologically sustainable. Results from this thesis suggest that any level of commercial grazing is detrimental to some woodland birds. Habitats with high levels of grazing support a species-poor bird assemblage dominated by birds that are increasing nationally. However, provided trees are not cleared and landscape context is not intensively used, a rich and abundant bird fauna can coexist with moderate levels of grazing, including iconic woodland birds which are declining elsewhere in Australia.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.