Includes bibliographical references. / African elephants are known to be important agents of structural and compositional changes in several vegetation types in southern Africa. This is of concern for biodiversity conservation and management of wildlife areas in the region. This study assesses how increasing elephant numbers have already altered and are likely to continue to modify the structure and composition of mopane woodlands in the south-eastern lowveld of Zimbabwe. Several features of vegetation structure and composition were quantified and compared across areas under three different elephant densities: low, intermediate and high. We assessed the degree, nature and patterns of damage incurred by woody plants within these woodlands to determine how elephants are both driving and responding to the changes in the vegetation. Increasing elephant densities were associated with increased losses of tall trees and the resultant development of a coppiced shrub layer. As elephant densities increased from low to intermediate levels, so did the level of damage to both shrubs and trees. However, elephants appeared to exhibit a functional response such that the increase in damage to the shrub layer was proportionately higher than to trees, probably because the coppiced shrub layer was a preferable food source. Nevertheless if elephant density increases further to high levels, damage to trees is likely to continue increasing suggesting that tree losses are likely to continue. In particular, the high level of bark damage to emergent trees is predicted to contribute greatly to further tree losses. This study provides evidence to suggest that increasing elephant impact is capable of completely converting tall mopane woodlands to shrublands. This is likely to have indirect effects on the ecosystem functioning and diversity of these areas as well as tourism, and is consequently of concern for local management. Continued monitoring of these woodlands and management of elephant abundance is advisable if a total conversion to shrubland is to be avoided.

No description available.

The global decimation of carnivore populations has been called one of mankind’s most pervasive impacts on the natural world. Human-wildlife conflict over the threat (both real and perceived) predators pose to livestock is one of the leading causes of carnivore decline worldwide. Livestock guarding dogs have been widely acclaimed as an environmentally friendly tool for reducing this conflict, yet little is known about the hidden costs of their presence. This study used scat analysis to reconstruct the diet of livestock guarding dogs and local caracals (Caracal caracal) to better understand their impacts on biodiversity and livestock in Namaqualand, South Africa. For livestock guarding dogs, 187 scats revealed the consumption of (from most to least frequent): livestock, wild mammals (including ten native species), vegetation, anthropogenic items, invertebrates, reptiles, fruit and birds. However, the diet of dogs accompanied by a human attendant differed significantly (χ 2 = 94.075, p < 0.001) from dogs guarding sheep independently. While 75% of scats collected from dogs operating independently contained domestic ungulates, less than 5% of scats from dogs with a human attendant contained livestock. For caracals, 185 collected scats were analysed across two land uses: Namaqua National Park and surrounding farms. Eighteen mammalian prey species were identified in their overall diet, with medium sized (1-10 kg) mammals (particularly the rock hyrax, Procavia capensis) accounting for more than half of consumed prey (59.1%). Small mammals (<1 kg) and wild ungulates were consumed more frequently in the protected area than on farmland. Livestock comprised 16% of the mammalian biomass consumed on farms, however no livestock was found in caracal scat within the protected area. These results support a growing body of research that suggests caracals do not prefer livestock, but will consume them when their numbers are considerably higher than that of wild prey, as is the case on many farms. Although this analysis cannot differentiate between predation and scavenging, the results provide novel insight into the potential impacts of livestock guarding dogs on the landscape and their overall effectiveness as a nonlethal predator management tool. This can help inform livestock guarding dog training and predator management while providing key information about the diets of both an indigenous and introduced predator.

No description available.

Includes bibliographical references. / The mechanism by which trees die following a low intensity fire is poorly understood. Traditionally, cambial necrosis (Carbon starvation hypothesis) has been used to explain post-fire tree mortality, however, this does not explain why some trees die within days following a fire. To address this, the hydraulic death hypothesis argues that post-fire tree mortality is a result of a reduction in hydraulic conductance rather than the necrosis of cambium. There are a number of proposed mechanisms by which hydraulic failure can occur during a fire: firstly, plume-induced cavitation as a result of high vapor pressure deficit (VPD) in a fire-plume has been shown to reduce hydraulic conductance. Secondly, changing surface tension as water is heated has also been shown to increase the chance of cavitation. The final mechanism is a reduction in conductance as a result of direct xylem vessel deformation due to the visco-elastic properties of xylem walls (lignin). In order to determine the relative importance of each proposed mechanism, stems of Kiggelaria africana and Eucalyptus cladocalyx were exposed to 70 and 100„aC in two treatments designed to isolate the effect of each mechanism. An oven treatment was used as a surrogate for a fire-plume in order to demonstrate VPD-induced cavitation and a water bath treatment (transpiration inhibited) was used to demonstrate xylem deformation (along with microscopy). This was possible because post-treatment flushing was indicative of the initial cause of the reduction as cavitation is reversible while deformation is permanent. The data was then explored using a Hydraulic Death model we created based on a xylem conductance model from literature. The results showed that VPD-induced cavitation as well as deformation are able to reduce hydraulic conductance in trees exposed to fire, however, E. cladocalyx showed higher loss of conductance at 65„aC than K. africana and deformation was only seen to occur in water bath treatments and only in K. africana. Here we propose that a chain of events provides a mechanism for slowing the rate of heating in branches exposed to a fire-plume and that cavitation plays a protective role. Model exploration implied that vulnerability segmentation is responsible for preventing fire-plume induced runaway cavitation. This is in agreement with the ¡§safety valve hypothesis¡¨, however, rather than drought stress, it is a fire-plume which causes the cavitation. It was also found that E. cladocalyx was able to prevent deformation because of xylem vessel characteristics (thick vessel walls) and not bark properties. We propose that the necrosis of cambium and phloem leading to the inability to refill cavitated vessels is the actual cause of mortality in trees exposed to low intensity fires. The ability to refill is dependent on water availability and carbohydrate content, which is highly sensitive to drought. As resprouters store water and carbohydrates in lignotubers and stems, they are less sensitive to pre-fire conditions. However, the survival of cambium and phloem is essential to the refilling process and thus the mechanism for reducing heat transfer, bark properties as well as xylem characteristics work in combination to determine persistence after a fire.

Bird-wine grape damage is a globally acknowledged problem that has been the subject of considerable research in many wine growing regions. However, despite the Western Cape of South Africa being a major wine grape growing region, very little research has quantified bird damage in this region and very little is known about the extent of the problem. This research aimed to quantify bird damage to wine grapes in four grape growing regions of the Western Cape, through questionnaires. It also aimed to determine the factors that might explain the patterns of damage observed. 102 questionnaires were sent to the wine farms, and 52 were returned. Of the respondents, 71% reported bird grape damage. The amount of damage per wine farm ranged between 0% and 15% of the total rows of vines across a farm. When exploring the factors associated with whether a wine farm experienced bird damage, it was found that the border habitat of a farm was a significant factor. The composition of the border habitat greatly influenced the probability of bird damage. The PCA showed that tall trees, Fynbos and residential areas specifically increased the probability of bird damage. Within farms that experienced damage, it was found that in different vineyard blocks the areas closer to the edge of a vineyard and to trees were significantly more susceptible to bird damage. The most common reported damage-causing bird species were Red-Winged Starlings (Onycognathus morio) and White-Eyes (Zosterops lateralis). Damage was reported to occur mostly one month before harvest and at harvest time. This research provides a baseline for understanding the nature of bird damage in these regions and will aid future quantitative studies aimed at the management of the problem.

No description available.

In understanding the behaviour of social-ecological systems, much focus has been placed on the role of institutions that govern how natural resources should be managed, and the biophysical processes affected by this management. Somewhat less attention has been given to the role played by the natural resource managers themselves. Novel insight into social-ecological systems can be gained from understanding why managers act as they do and how management actions become reinforced into (un)sustainable management regimes. In this thesis I applied a social-ecological systems perspective to the phenomenon of private land conservation. With increasing interest in the role that the private sector can play in global conservation efforts, a pertinent but largely unexplored question is whether private land conservation areas (PLCAs) can conserve biodiversity over sufficiently long time scales. This thesis contributes to social-ecological systems theory through an in-depth analysis of the multi-scale interactions among natural resources, managers and socioeconomic processes, which affect PLCA management practices and their sustainability. The potential ability for commercially operated PLCAs to generate the funds necessary for their maintenance makes them an attractive conservation strategy in an economically-orientated world. There are concerns, however, that (a) their long-term sustainability may be dependent on their ability to become and remain financially viable; and (b) they may be tempted to prioritize profit over biodiversity protection in their management practices, thereby jeopardizing their ecological sustainability. The objectives of this thesis were to investigate if, how and why commercial PLCA managers (a) meet their financial objectives and (b) adopt unsustainable ecological management practices. During 2014 and 2015 I interviewed the managers of 72 commercial PLCAs in the Western and Eastern Cape Provinces of South Africa, a region that supports a rapidly growing yet poorly understood PLCA industry. I applied theories from organizational ecology to understand patterns in the income-generating strategies adopted by PLCA managers. Distinct business models were evident, differentiated by incompatibilities in the biophysical (size, fauna) and socioeconomic (activities, affordability) characteristics of these conservation areas. PLCAs characterized by financial objectives but unprofitable business models suggest that these incompatibilities constrain the ability of managers to effectively adapt to their economic environment, a concept known as "structural inertia" in organizational ecology. Profitability was highest on PLCAs that supported megaherbivores and large predators, reflecting international tourist preferences for charismatic game. Managers' financial objectives influenced the strategies that they employed to manage these mammals. When managers used revenue-generation to inform their management decisions, they undertook management actions that enabled them to maximize and stabilize game populations. While this intensive management resulted in higher revenues, it corresponded in many cases with a lack of ecological monitoring and an increased risk of overstocking game. Regional policy guidelines for large predator management both mitigated and exacerbated the mismatch between financially-desirable and ecologically-sustainable management, depending on whether species-specific guidelines were ecologically appropriate or not. Simulations of a mechanistic PLCA model were used to test whether adopted management strategies influenced the observed constraints on business model adaptation. If the income-generating potential of an adopted business model was low, managers were unable to accumulate the capital necessary to overcome the biophysical and socioeconomic incompatibilities that separated business models, constraining their adaptive capacity. Intensively managed PLCAs were able to generate a more stable annual income, accumulate more capital and overcome constraints on adaptation faster than PLCAs managed according to ecological monitoring. This unique, large-sample assessment of the social-ecological mechanisms underlying PLCA sustainability emphasizes the significant role that managers can play in promoting resilient social-ecological systems. When financial viability is an important consideration, broad-scale socioeconomic factors can influence fine-scale management decisions. Through constraints on adaptation, and the presence or absence of corrective feedbacks between management actions and ecological monitoring, these management decisions can become reinforced into management regimes on a trajectory towards, or away from, sustainability. This study therefore provides a novel contribution to our understanding of how the interactions between managers and ecosystems influence the behaviour of social-ecological systems.

As the world's human population increases, so does the competition for natural resources between humans and wildlife. This competition may be intense for apex predators, such as raptors, which generally require large natural areas in order to maintain their populations. Anthropogenic development within territories can cause individuals to either abandon these sites, reduce their breeding productivity, or cause direct mortality to the territory holding birds. To mitigate such impacts, one method, employed as part of Environmental Impact Assessments (EIA), is the use buffer circles centred on nest sites. Within these buffers the most damaging forms of development are prohibited. This approach assumes that raptors use the space around their nest in a uniform way, but this assumption may not always be correct and few have evaluated the effectiveness of buffer circles at protecting a species' home range. This study uses tracking data to evaluate the effectiveness of buffer circles to cover the ranging movements of six southern African raptor species, throughout the year, as well as during their breeding and non-breeding season. My study revealed that buffer circles whose dimensions were based on the species' 95% Kernel Density Estimate (KDE) did relatively well at capturing the proportion of individual GPS fixes, but did less well at capturing the KDE area from tracked birds. For buffer circles to capture 95% of the home range polygons (95% KDE) they would generally need to be at least twice as large as those that were derived from the 95% KDE home range area, and for some species with very large home ranges (e.g. Lappet-faced Vultures) even buffer circles that were 3 times the size failed to cover 95% of the KDE polygons.

There are few studies that empirically test whether education can improve stakeholder support for a particular wildlife management/conservation intervention. Evidence-based decision making is critical for conservation actions, especially when people and wildlife are engaged in negative interactions to the detriment of both. Rising human and baboon numbers in the Cape Peninsula of South Africa is associated with increasing levels of damage to properties, both indirect and direct human-induced injury and mortality to baboons. A possible management intervention to reduce these negative interactions is a baboon-proof electric fence which has already been shown to be very effective in the suburb of Zwaanswyk on the Peninsula but surprisingly has low public acceptance. For this study, I produced a short survey that included an educational video on the welfare, conservation, and lifestyle benefits of a baboon-proof electric fence. Two versions of the same survey were created but with the educational video provided either before or after questions pertaining to the level of support for the fence. Using a randomised controlled trial method, I tested whether the level of support for the fence changed according to the order of viewing the video. I also used a pre- and post-test method to explore whether level of support for the fence changed for those who watched the video at the end and were given a chance to answer the question again about level of support for the fence. The results showed that watching the video before the survey increased the average marginal probability of supporting an electric fence by 15 percentage points and reduced the average marginal probability of not supporting the fence by 17 percentage points. There was also a significant difference in level of support for the fence in the pre- and post-test experiment, and my results show that women were more likely to adjust their response in favour of the fence. Implications of these results are significant as managing a peri-urban species is considerably more effective if there is collaboration, agreement, and support for management measures between and within key stakeholders. This study contributes to the emerging literature on the importance of education in managing human-wildlife conflict.