Territories and home-ranges are the smallest spatial units of species' presence in a landscape and they determine in what ways and on what scales animals perceive and use their environments. Their sufficient sizes encompassing enough resources are critical for survival and reproduction of individuals. Processes and factors affecting territory and home-range sizes therefore belong to fundamental ecological issues. Despite its importance, the knowledge of variation in avian territory and home-range size at large spatial scales is poor. So far it has comprised mainly the findings that the used area is determined by individual's energetic demands, dependent on body size and diet type, and by environmental productivity. Therefore, the aim of this thesis was to use data gathered from available literature to describe the variation in territory and home-range size of birds. I was curious what was the nature of territory and home-range size frequency distribution; whether the sizes were species-specific and whether and how these sizes were affected (beside the body mass and diet type) by various environmental characteristics, such as latitude, temperature, precipitation, seasonality, altitude and habitat type. I have found that the territory and home-range size frequency distribution is approximately...

Climate change is considered one of the greatest future threats against biodiversity. One predicted consequence of a global temperature increase is that biomes will move against the poles, which will force species to either adapt to an unsuitable habitat or follow their climatic range shift. A common way to assess the future geographical distribution of a species is to predict their future climatic range. However, this excludes factors that could interfere with the species ability to follow their range shift, such as dispersal ability. The importance of expansion-related traits are often assumed rather than quantified. This study investigated if the specialist butterfly Pyrgus armoricanus, living at its northern range limit in south Sweden, will be able to expand north as the temperature increases. The study also explored the importance of six traits on a butterfly’s range shift ability; habitat specialization, growth rate, emigration probability, establishment probability, dispersal vagrancy and dispersal probability. The study found that the butterfly Pyrgus armoricanus will not be able to expand north in Sweden due to low dispersal ability and habitat availability. The most important traits for a butterfly’s ability to expand north in Sweden was growth rate, dispersal ability and habitat generalisation. Specialized butterflies dependent on well managed meadows will have limited success in following their northern range limit, and restoration is necessary to avoid future biodiversity degradation.

Lumbar intervertebral disc disorder is a spinal condition that affects the normal function of the intervertebral discs mainly due to the natural aging process. This condition can manifest itself in pain and limited motion in the legs, amongst others. Posterolateral Fusion (PLF) and Posterior Lumbar Interbody Fusion (PLIF) are two of the most used surgical procedures for treating lumbar intervertebral disc disease. Although these procedures are commonly used and performed successfully the impact in terms of the stresses developed in the posterior implants employed and in the spinal components adjacent to the surgical site has not been exhaustively investigated. In addition, the consequences of the procedure on the reduction of the Range of Motion of the lumbar spine is not clearly understood. The objective of this research is to investigate the effect of one-level spinal fusion of lumbar segment L4-L5 on the stresses and the range of motion at the remaining, adjacent lumbar levels. Four 3 dimensional finite element models of a lumbosacral spine were created from Computer Tomography data (CT scan). The models were used to investigate four surgical scenarios, including the use of 0o and 4o interbody cages, in addition to the un-instrumented spine for flexion, extension, torsion and lateral bending motions. The predictions obtained from the models enabled the mechanical behaviour of the lumbar spine following fusion surgery using 0 o and 4o cages to be investigated and compared. In addition, a clinical study was performed to quantify the reduction in the range of motion for subjects who had undergone L4/5 posterior lumbar interbody fusion surgery. The clinical results were compared to those of subjects who had not undergone surgery and to the range of motion predictions from the computational model. The results from this research demonstrate that the insertion of posterior instrumentation does not have an impact on the spinal structures above the L3/4 intervertebral disc. However, the pedicle screws and the insertion of the interbody cages causes stress levels in the area adjacent to the surgical site to rise which could promote accelerated degeneration of the discs. Additionally, this study demonstrates how the pedicle screws are affected by the surgical spinal fusion techniques. Furthermore, the investigation demonstrates how posterior lumbar interbody fusion causes the range of motion of patients that had undergone this surgery to decrease. The results from the comparison of the behaviour of the use of 0º and 4º interbody cages in L4-5 posterolateral fusion demonstrates that the stress levels in the adjacent vertebrae, intervertebral discs and pedicle screw fixation system increase when 4º are used cages than when 0º cages were employed. The results from the in-vitro study show a decrease in the range of motion of the subjects who had undergone L4/5 posterior lumbar interbody fusion surgery when compared with the subjects with no low back pain history. This indicates that the PLIF surgery combined with the normal disc degeneration is subjected to higher stresses than the healthy spine.

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This study, undertaken under the auspices of the Centre of Wildlife Management and the former Centre for Indigenous Knowledge (University of Pretoria) was conducted in Maputaland, with special reference to the Tembe Elephant Park, Sileza Nature Reserve and in the neighbouring traditional wards (izigodi) of Mbangweni, Bhekabantu, Kwandaba, Zama-zama, Tsokotho, Manqakulani (which includes the Tshanini Community Conservation Area), Lulwane, Mntikini, Ndlondlweni, Ndovu and Sibonisweni. The main objective of this study was to evaluate the range condition and grazing capacity of the natural veld. A management plan for the Tshanni Community Conservation Area is presented, which could potentially serve as template for similar areas. To accomplish these objectives a cattle as well as a vegetation survey were conducted. The cattle surveys were conducted among the local communities (mentioned above) to identify and to evaluate the role played by cattle in the everyday lives of the communual people and to identify the types of grazing regime (practices). The vegetation surveys were undertaken to evaluate the range condition, grazing capacity and grazing quality of the herbaceous vegetation. The study also included methods to determine the number, distribution and health status of cattle present in the study area. The results indicated that social and religious values that were associated with cattle in the older Zulu culture have clearly faded in the Tembe Traditional Area. The current values of local communal people regarding cattle were concentrated on utilization and investment for future uncertainties. Cattle were still seen as wealth and status symbols in the local communities and were highly prized possessions if they could be obtained. The official cattle numbers did not seem to reflect the actual cattle numbers in the study area at the time of study. It was also clear that cattle were distributed in areas where the water supply was sufficient. The main grazing areas were thus in the east of the study area in the hygrophilous vegetation to the east of Manqakulani and mainly in Ndlondlweni. No specific grazing management practices could be identified and the grazing system could be best described by a continuous grazing practice. Grazing was not restricted to any part or piece of land inside the specific isigodi as long as the cattle stayed out of other people’s cultivated land. Overstocking the grazing area was not occurring at the time of the study as the stocking density was well below the area’s capacity. The general perception of the majority of the cattle owners was that their cattle were in a good condition. An analysis of the results obtained from the vegetation survey indicated that the herbaceous biomass yield did not vary noticeably among the management units within a site as well as among the different sites. The small fuel loads in the Tshanini Community Conservation Area did not necessitate burning and were probably below fuel loads needed for fires to spread. However, it was frequently observed that fire could be maintained in areas where the herbaceous biomass yield was below 2 000 kg/ha. The results represented in this study also indicated that the management units of the Tshanini Community Conservation Area were generally in a good condition and that the range condition of the Tshanini Community Conservation Area compared relatively well with the other reserves in the study area. The modified Ecological Index Method was reliable and time saving, yet simplistic enough for assessing the range condition of the management units of the Tshanini Community Conservation Area and the entire Tembe Traditional Area. The stocking density must be adaptable and based on the quantity and quality of grazing available at any time. The model that was used to calculate the stocking density of the study area allows for several elements to be modified to suit the conditions on a particular wildlife reserve at a particular time. For example, in future it may become necessary to adjust the percentage composition of graze and browse in the diet of some animal types for the calculation of Grazer Units (GU) and Browser Units (BU), mainly because the diet of the same type of animal may vary regionally. Finally, changes in the choice of the types of wildlife can be accommodated depending on the preferences and objectives of the management and steering committee of the Tshanini Community Conservation Area. This model can be applied as a tool for active adaptive management because it allows more control over the quantity and quality of available food plant resources and hence the stocking density of animal resources. It is proposed that the results of the present study be combined and integrated into a Geographic Information System (G.I.S.) database that could form the ecological basis for future management planning of the Tembe Traditional Area as part of the Usuthu-Tembe-Futi Transfrontier Conservation Area. / Dissertation (MSc)--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

To proffer a sustainable solution to ecological degradation in rangeland ecosystems as a consequence of fire, grazing and browsing, an understanding of rangeland ecological processes is vital. Due to the complexity of ecological processes and their interrelationships, it is usually difficult or expensive to directly measure status of ecological processes. Therefore, biological and physical characteristics are often used to indicate the functionality of ecological processes and site integrity. Long-term effects of fire, grazing and browsing on characteristics of the vegetation and organic matter and their subsequent effects on selected rangelands ecosystem ecological processes was conducted at Honeydale section of the University of Fort Hare farm in the Eastern Cape Province of South Africa and Matopos Research Station in Zimbabwe. In this study, attributes of biotic community integrity (species richness, composition and diversity), soil stability (basal cover, standing dead grass biomass, tuft to tuft distance, tufts diameter, canopy distance and stem to stem distance), productivity and plant vigour (grass yield, total canopy volume, plant height, canopy height, canopy diameter, main stem diameter, sprouts diameter and number of sprouts) and hydrologic function and nutrient cycling (grass litter biomass, soil organic carbon and microbial biomass carbon) were used to estimate long-term effects of burning, grazing and browsing by goats on the functionality of ecological processes in the rangeland ecosystem. Burning did not have differential effect on grass species richness (P>0.05), woody species diversity as well as compositional percentage for D.eriatha, C.plurinodis, S.fimbriatus, A.karro and E.rigida. Burning increased decreasers and increaser II species proportions and reduced (P ≤ 0.05) grass yield, total canopy volume, tree height, canopy height main stem diameter and sprouts diameter. Long-term burning, grazing, and goats browsing had differential effects on site stability. The effects on basal cover, tuft to tuft distance, tufts diameter, canopy distance and basal distance as a consequence of long-term burning, grazing, and goats browsing were not significantly different, whereas the effects on standing dead grass biomass as a result of long-term burning frequencies were significantly different. Long-term effects of burning followed by ten-year period of fire exclusion had significantly different effects on tuft-tuft distance but did not have statistically different effects on tufts diameter, canopy distance and basal distance. Long-term burning grazing and browsing had significantly different effects on attributes of hydrologic functions and nutrient cycling in the rangeland ecosystem (grass litter biomass, SOC and BMC). Long-term effects of burning followed by ten-year period of fire exclusion had significantly different effects on grass litter biomass, and SOC. Through their effect on vegetation and organic matter characteristics, burning, grazing and browsing could influence functionality of selected rangeland ecological processes such as biological community integrity, productivity and plant vigour, site stability, hydrologic function and nutrient cycling.

This dissertation addresses the issue of robustness in proton therapy treatment planning for cancer treatment. Proton therapy is considered to be advantageous in treating most childhood cancers and certain adult cancers, including those of the skull base, spine and head and neck. Protons, unlike X-rays, have a finite range highly dependent on the electron density of the material they are traversing, resulting in a steep dose gradient at the distal edge of the Bragg peak. These characteristics, together with advancements in computation and technology have led to the ability to plan and deliver treatments with greater conformality, sparing normal tissue and organs at risk. Radiotherapy treatment plans aim to meet set dosimetric constraints, and meet them at every fraction. Plan robustness is a measure of deviation between the delivered dose distribution and the planned dose distribution. Due to the same characteristics that make protons advantageous, conventional means of using margins to create a Planning Target Volume (PTV) to ensure plan robustness are inadequate. Additional to this, without a PTV, a new method of analysing plan quality is required in proton therapy. My original contribution to the knowledge in this area is the demonstration of how site- and centre- specific robustness constraints can be established. Robustness constraints can be used both for proton plan analysis and to identify patients that require plans of greater individualisation. I have also used the daily volumetric imaging from patients previously treated with conventional radiotherapy to quantify range uncertainty from inter- and intra-fraction motion. These new methods of both quantifying and analysing the change in proton range in the patient can aid in the choice of beam directions, provide input into a multi- criteria optimisation algorithm or can be used as criteria to determine when adaptive planning may be required. This greater understanding in range uncertainty better informs the planner on how best to balance the trade-off between plan conformality and robustness in proton therapy. This research is directly relevant to furthering the knowledge base in light of HM Government pledging £250 million to build two proton centres in England, to treat NHS patients from 2018. Use of methods described in this dissertation will aid in the establishment of clear and pre-defined protocols for treating patients in the future.

Aim It is commonly asserted that climate presents the primary constraint on species’ geographic distributions, and therefore, that species' ranges shift in response to changing climate given their specific climatic tolerances. However, supporting evidence is surprisingly inconsistent. Alternatively, spatially structured processes (e.g., dispersal) could more strongly determine species’ geographic distributions. Is climate the primary determinant of species’ geographic distributions, or might non-climatic, spatial processes constitute a stronger influence, such that the effect of climate is indirect? This study tests a number of predictions made by each of these hypotheses, during a single period of time. Location Contiguous United States and southern Canada. Methods We used 19 species of passerine birds whose distributions fall entirely within the area sampled by the North American Breeding Bird Survey from 1990-2000. We related these distributions to the mean breeding season climate, geographic locations and neighbourhood effects. Two spatial scales were addressed to assess the geographic location of species’ ranges and species' distributions within ranges. Results On average, geographic coordinates and a model representing neighbourhood occupancy outperform a simple climatic model. After controlling for geographic coordinates, species occupancy is poorly related to climate. A neighbourhood model on average accounts for the majority of variance captured by geographic coordinates within ranges, and more for the continental placement of ranges. Spatially explicit variables are more important than macroclimatic variables in a predictive model of species occupancy on average. Main Conclusions The geographic distributions of wide-spread North American passerine birds appear not to be primarily determined by climate. Our results are consistent with the hypothesis that localized spatial processes such as dispersal are stronger determinants of both continental range placement and within-range distributions of North American birds.

Climate change is an important contributor to the modification of many bumblebee species’ range boundaries. It was linked to widespread decline at the southern edge of their distribution and to their inability to colonize new areas at the northern edge. Additionally, bumblebee decline is aggravated by other anthropogenic threats like land use change, agricultural practices and pathogen spillover. Predicted consequences are numerous, and could lead to severe economic and ecological impacts on human populations. A species-specific assessment of potential climate change impacts on North American bumblebees, based on the most recent global change scenarios as used in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), was done for the first time. Using a massive dataset of georeferenced bumblebee observations and general circulation models, a series of species distribution models explore the impact of different climate change scenarios on climatically suitable areas of 30 bumblebee species. Northward range shifts occur in most bumblebee species’ projected climatic niches, revealing potential hotspots – places projected to be climatically suitable to multiple species – under future climate scenarios. Areas where species are likely to be lost in the absence of intervention are substantial, particularly in eastern parts of the continent. Models showed significant contractions of current ranges even under the very optimistic scenario in which all species disperse at 10 km/year. Results indicate that managed relocation as well as habitat management should be considered as a conservation strategy for some species. This research serves as a foundation for broader discussion and research in a nascent research area. It may assist in establishing localities where first conservation efforts could be directed for vulnerable bumblebee species.

Five periods of ice advance in the North Klondike-upper Blackstone basins of the Ogilvie Mountains are recognized by the downvalley sequence of progressively older moraines. The youngest occurred during the last millennium and is represented by glacierets and fresh moraines. The other advances are of the Pleistocene Epoch; from youngest to oldest they are: Age I (valley glacier stage), Age II (transection glacier), Age IIA (transection glacier with piedmont) and Age III (mountain ice cap). Evidence for Age III is limited to the north slope of the ranges. Age IIA was recognized only on the north slope and may represent a slightly older pulse of the Age II. This chronosequence is tentatively correlated with those elsewhere in the northern Cordillera. Within the region an array of surficial elements indicates that a continuous and discontinuous mosaic of processes have operated interdependently during the Quaternary. A product of these processes is mapped under one of eight facies - attention being directed to the varieties of features associated with the glacial and periglacial cycles. Of the latter, active, inactive and degradational forms exist. Strong correlations between the distribution of some types of surficial features and the underlying bedrock geology are recognized. No changes in morphology, permafrost distribution, pebble weathering, pedogenesis and floral succession could be related to the ages of the Pleistocene moraines. The influence of permafrost on all ages of moraines, the variability in their environment of deposition, and an edaphic and climatic discontinuity produce greater differences than does the age factor. In the northern half of the study area, permafrost and associated phenomena were observed to greatly retard chemical alteration; on the other hand, they permit the development of only a vegetational and pedological "polyclimax", rather than a single mesic climax, in a time span of less than 11,000-15,000 years. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate