Thesis (MSc. (Zoology)) --University of Limpopo, 2008 / Refer to document / National Research Foundation - Thuthuka programme

In 1986, Hurricane Bonnie passed over Wier Woods, a well-developed mesic forest in the Big Thicket Area of Texas, causing substantial tree mortality and opening several canopy gaps. Mortality was high during the hurricane interval, but did not vary significantly among species. Ingrowth into the 4.5 cm DBH size class was accelerated by the hurricane. Tree growth was largely unaffected by the hurricane; however, small individuals of all species experienced slightly increased growth rates after the hurricane. Mortality in the years after the storm did not decrease or increase. Even though Bonnie caused approximately three times "normal" mortality, there was only a slight decrease in basal area from 1985 to 1987. The low frequency of hurricanes and the modest effects of this hurricane suggest that hurricanes may have limited effects on the structure and dynamics of forests of the Big Thicket.

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / Due to their popularity for tourism, giraffes are being introduced into Thicket areas within the Little Karoo region of the Western Cape. However, information regarding the activity budgets and diet selection of these giraffes is lacking. Therefore, this study aimed to achieve three objectives; to determine the diurnal activity budget, diet composition and browsing levels, and the estimated browsing capacities of extralimital giraffe. The study was conducted on two privately owned farms, namely Kareesbos Private Game Reserve and Tsumkwe Private Game Reserves. Observations were completed on both study sites using the interval scan method, whereby observations were conducted on all visible individuals from 6 am – 6 pm for four days every 3 months (winter, spring, summer and autumn). Observations found browsing to be the most dominant activity displayed by both populations, with walking and rumination being the second and third most dominant activity. Females browsed more than males in both study sites. Dietary observations showed four species (Pappea capensis, Portulacaria afra, Euclea undulata and Searsia longispina) and five species (Searsia longispina, Euclea undulata, Pappea capensis, Vachellia karroo and Grewia robusta) to comprise approximately 90% and 80% of their diet in Kareesbos and Tsumkwe respectively. The importance of flower bearing species (Lycium spp. and Rhigozhum obovatum) increased during the spring and summer seasons in both study sites. In addition to the diet selection, browsing by both giraffe populations was shown to occur mostly below 2 m. Estimated browsing capacities for Kareesbos and Tsumkwe were 25 and 21, and 107 and 88 ha per giraffe, respectively, for the respective browse height strata of less than two metres and five metres. It is suggested that browsing capacities of less than two metres be considered when stocking giraffe and the number of individuals adjusted accordingly on each farm, due to the continuous low browsing of giraffe at less than two metres. Furthermore, results indicate that these giraffes have adapted to take advantage of forage available in ecosystems outside their natural ranges. Low foraging heights suggests possible niche overlap with other browsers, which may result in increased competition for food when it becomes limited. Long term ecological monitoring of extralimital populations and appropriate management procedures are therefore required to avoid the displacement and degradation of indigenous fauna and flora within the Little Karoo, and possible mortalities amongst the giraffe populations.

The Big Thicket National Preserve is located in the southern part of the United States. It is within the Pineywoods vegetation region of southeastern Texas. This study area was the Canyonlands Unit, a unit located entirely within Tyler County, Texas. This unit is one of the most recently acquired units within the Big Thicket National Preserve. It was acquired in 1993 and is composed of 1,476 acres. The purpose of this study was to make a complete list of all the vascular plant species within the Canyonlands Unit. The numbers of plant species within this unit were compared to three other units within the preserve that are relatively close to the Canyonlands Unit. The plant species within these units were compared on number of species that are native versus introduced, longevity, season of growth, plant type (woody versus herbaceous), plant group (monocots, dicots, gymnosperms, ferns) and upland versus wetland plants based on region six wetland indictor values. The wetland plant species were compared among themselves as the number of obligate species versus facultative wetland plant numbers. This study also shows the number of invasive and weedy species within the Canyonlands Unit. Along with determining the number of plant species and comparing those with the number of species in the other units, a Cluster Analysis and Indicator Species Analysis was conducted on the woody vegetation within the Canyonlands Unit in order to determine woody plant communities. These analyses were conducted by using the statistical software, PC-ORD.

<I>Rhododendron maximum</I> L. (Ericaceae) is an evergreen shrub that grows in dense thickets and currently covers large areas of the understory in the deciduous forests of the southeastern United States. Thickets of R. maximum are inhibitory to recruitment and regeneration of many understory plants including canopy tree seedlings. By effectively lowering the survivorship of woody species trying to establish within thickets, <I>R. maximum</I> could influence stand level regeneration patterns and ultimately the community structure of these deciduous forests. This dissertation outlines research conducted to determine if: 1) below and above ground resources are lower within thickets of <I>R. maximum</I> when compared to forest sites where <I>R. maximum</I> is absent; 2) <I>Quercus rubra</I> and <I>Prunus serotina</I> seedlings growing in thickets have lower mid-day photosynthetic rates; 3) <I>Quercus rubra</I> and <I>Prunus serotina</I> seedlings growing within thickets are low light acclimated when compared to seedlings growing in forest without <I>R. maximum</I>; 4) the presence of <I>R. maximum</I> constrains CO₂ assimilation of <I>Quercus rubra</I> seedlings exposed to light flecks of different durations and intensities; 5) the presence of <I>R. maximum</I> constrains the light fleck responses of <I>Quercus rubra</I> seedlings exposed to eight light flecks in rapid succession; and 6) canopy openness regulates the capacity of <I>Quercus rubra</I> seedlings to assimilate carbon when exposed to eight consecutive light flecks. <I>Rhododendron maximum</I> thickets altered resource availability for seedlings when compared to areas of forest without <I>R. maximum</I>. Diffused photosynthetically active radiation (PAR) averaged less than 5 μmol m⁻² s⁻¹ throughout the growing season in sites with <I>R. maximum</I> in comparison to 10-30 μmol m⁻² s⁻¹ in sites without <I>R. maximum</I>. Soil moisture content, measured using Time Domain Reflectometry was approximately 6% lower in forest sites with <I>R. maximum</I> compared to sites without <I>R. maximum</I> throughout the growing season. Most nutrient concentrations (e.g.,, C, N and most cations) and nitrogen mineralization rates were significantly lower in sites with <I>R. maximum</I>. Temperature and atmospheric relative humidity are slightly lower under thickets of <I>R. maximum</I>. In general, sites with <I>R. maximum</I> are associated with lower resource availability above and below ground in comparison with sites without <I>R. maximum</I>. Attenuation of below canopy PAR by thickets of <I>R. maximum</I> negatively influences the photosynthetic capacity of <I>Quercus rubra</I> and <I>Prunus serotina</I> seedlings as indicated by measurements of mid-day photosynthesis. In 1996, the seasonal mean mid-day photosynthetic rate of first year <I>Q. rubra</I> seedlings growing in <I>R. maximum</I> thickets (1.3 μmol m⁻² s⁻¹) was 62% lower than the seasonal mean mid-day photosynthetic rate (2.1 μmol m⁻² s⁻¹) of seedlings growing in forest sites without <I>R. maximum</I>. For second year seedlings in 1997, seasonal mean mid-day photosynthesis was 183% higher for plants growing outside of thickets (1.7 μmol m⁻² s⁻¹) compared to the mean rate (0.6 μmol m⁻² s⁻¹) for plants located within thicket sites. The mean mid-day PAR available to seedlings located in forest sites without <I>R. maximum</I> during measurements of photosynthesis was 354% higher in 1996 and 257% higher in 1997. First year <I>Prunus serotina</I> seedlings growing in forest without <I>R. maximum</I> also had greater seasonal mean mid-day photosynthesis (0.7 μmol m⁻² s⁻¹) when compared to the mean rate (-0.1 μmol m⁻² s⁻¹) for plants growing within thickets. <I>Prunus serotina</I> seedlings located in the presence of <I>R. maximum</I> received on average 67% less PAR. Photosynthetic acclimation to low light was assessed for <I>Q. rubra</I> and <I>P. serotina</I> seedlings growing under both forest conditions by measuring photosynthetic responses to light <I>in situ</I> using even aged one-year old seedlings. <I>Quercus rubra</I> seedlings growing in forest sites without <I>R. maximum</I> had significantly higher light saturated rates of photosynthesis. For both species, photosynthetic responses to light were otherwise similar irrespective of the presence or absence of <I>R. maximum</I>. The impact of the <I>R. maximum</I> subcanopy on understory PAR and subsequent influence on canopy tree seedling photosynthetic capacity implies that sunflecks are critical for seedling net carbon gain in these forest understory environments. To determine the effect of <I>R. maximum</I> on the photosynthetic response to sunflecks of oak seedlings, light flecks were simulated on 288 randomly chosen, even aged, two-year old seedlings <I>in situ</I>. Half of the seedlings were located within <I>R. maximum</I> thickets. Seedlings were randomly assigned one of four light fleck durations (30, 60, 120, and 300s) and one of three intensities (100, 500, 1000 μmol m⁻² s⁻¹). Half of all seedlings were dark pre-acclimated prior to light fleck simulations by covering with aluminum foil for at least 12 hours, while the remaining seedlings were pre-acclimated under ambient conditions. Analysis of covariance showed that a significant, positive, linear relationship exists between the length of a light fleck and total carbon gain during a light fleck for seedlings in forest sites with and without <I>R. maximum</I> regardless of pre-acclimation status, or light fleck intensity. Furthermore, there was a significant effect of <I>R. maximum</I> on the slope of the relationship such that following ambient pre-acclimation, seedlings located within thickets assimilated significantly less carbon with increasing light fleck length than seedlings located in forest sites without <I>R. maximum</I>. When seedlings were dark pre-acclimated there was no difference in carbon gain with increasing fleck length between seedlings in forest with and without <I>R. maximum</I> except for flecks of 1000 μmol m⁻² s⁻¹. The data lead to the conclusion that under natural conditions the presence of <I>R. maximum</I> likely prohibits <I>Q. rubra</I> seedlings from utilizing sunflecks as effectively as seedlings growing in forest sites where <I>R. maximum</I> is absent. Because sunflecks often occur clustered together during a short period of time during the day, another field study was conducted to further characterize the effect of <I>R. maximum</I> on the photosynthetic response of oak seedlings to eight consecutive light flecks. Within 10 paired sites, (i.e., with and without <I>R. maximum</I>) 3 even aged three-year old <I>Q. rubra</I> seedlings were selected. Over each seedling, a hemispherical canopy photograph was taken and analyzed for percent canopy openness. Each seedling was dark pre-acclimated for 12 hours and then exposed to eight light flecks in rapid succession during which time photosynthesis was logged every two seconds. Each light fleck was 500 μmol m⁻² s⁻¹ in intensity and lasted for 120s. Following each light fleck, leaves were exposed to 10 μmol m⁻² s⁻¹ PAR for 60s before the next light fleck. Mean carbon gain and maximum photosynthesis achieved during each light fleck was significantly lower for seedlings located in the presence of <I>R. maximum</I> for all flecks in an eight-fleck simulation. In addition, seedlings located within thickets generally had significantly lower pre-illumination photosynthesis following the first of eight light flecks. The mean photosynthetic light use efficiency of seedlings located in forest with <I>R. maximum</I> was significantly lower for the first six of eight light flecks in succession. Using regression analysis and analysis of covariance, percent canopy openness was used to explain the variation in carbon gained from all eight light flecks in succession for seedlings under both forest conditions. However, significant relationships failed to exist between under either forest condition and precluded using analysis of covariance. The results from these studies lead to the conclusion that light limitation is a major mechanism responsible for the extirpation of canopy tree seedlings from within thickets of <I>R. maximum</I>. Tree seedlings growing in forest sites with <I>R. maximum</I> receive less solar irradiance, have lower mid-day photosynthesis, fail to acclimate to the lower light conditions within thickets, and utilize sunflecks less effectively as well as less efficiently when compared to plants growing in forest sites without <I>R. maximum</I>. / Ph. D.

Historic research into the Virginia Springs reveals a collection of vital interconnected seasonal communities centered on retreat from the unhealthy environs of the coast and devoted to resort in the mountains. Prior to the Civil War the Virginia Springs became renowned internationally as the summer home of the region's and the nation's elite. The collapse of the southern economy during and following the war meant the reorganization and often the failure of most of the Springs. A revival of sorts took place among the Virginia Springs during the late 19th century, consciously referencing the earlier "golden age." Many Springs found new life as schools, church camps, retirement homes and smaller hotels. Many simply left the scene altogether. Today little remains in the landscape to suggest the scale and vitality of many of these dynamic seasonal communities. And yet retreat to a wilderness setting remains appealing. Perhaps most compelling are the persistence of landscape qualities that contributed to their reputations as places of healing and retreat, namely the mountain air, the wild scenery and the healing waters. The Virginia Springs are in fact at an ideal location and represent ideal conditions for a new chapter in our own relationship with wild nature. Preservation efforts ought to focus on articulating such a relationship of building to landscape. While the scale of such a retreat might not equal that of its predecessors, a revived Virginia Spring, such as the Healing Springs of Bath County, can say much about how we find retreat in the 21st century. / Master of Landscape Architecture

My thesis focuses on philosophical themes implicit in corridor conservation, using the Big Thicket National Preserve as an example. The way in which corridors, boundaries and communities are ambiguous, as both limits and connections, is dealt with. Corridor-patch matrices assemble ecological and human groups into temporary communities, often with conflicting interests. Such constellations foreground how a foreigner's boundary crossing is a notion important to both conservation and a philosophical study of being, seen as being always in relation with otherness. In this context, the notion of foreignness and Jean-Luc Nancy's idea of being-with is explored. Understanding the complex network of relations in which an entity exists leads to an awareness of its ambiguous nature. To facilitate judgment with such ambiguity, one needs a contextual understanding of a situation.

Meditation means awareness. It is a process inducing a series of steps, that leads to a state of consciousness which brings serenity and clarity. While the space we choose for meditating needs to reflect the state of clear mind, if possible, it should be isolated from the noisy city and in a natural pure land. This thesis investigates meditation theory and the natural context of Peggy’s Cove, as well as material and tectonic experiments, to design a New Meditation Centre in Peggy’s Cove, Nova Scotia. The design of the New Meditation Center proposes building as a new form of architecture, the form, material and construction of which engages the viewer to admire and respect our nature.

Svetimžemiais vadinami iš kitų kraštų kilę ir dėl žmonių veiklos į teritorijas, kuriose jie anksčiau neaugo, patekę augalai. Vienas iš tokių adventyvinių augalų yra varpinė medlieva (Amelanchier spicata) Taigi adventyvinių augalų skverbimasis yra nenutrūkstantis, su žmogaus veikla susijęs procesas, todėl galima teigti, jog tokių augalų šalyje ir toliau daugės. Varpinės medlievos (Amelanchier spicata) tyrimai buvo atliekami 2007-2008 m. liepos – rugsėjo mėn. keturiose skirtingose vietovėse, t.y. Antaviliuose, Aukštuosiuose Paneriuose, Žemojoje Veržuvoje ir Antakalnyje. Kiekvienoje vietovėje buvo pasirinktas 10000 m2 plotas. Plotas suskirstytas į 16 laukelių, o vienas laukelis sudarė 625 m2. Šiose vietovėse vertinant antžeminių dalių morfologinius parametrus buvo matuojamas stiebų aukštis, aukštis iki pirmos šakos, skersmuo, nustatomas stiebų brandos amžius bei absoliutus amžius. Tyrimų metu nustatyta, kad tankiausia buvo Antavilių populiacija. Pagal brandos amžiaus grupes visose tirtose populiacijose vyravo vegetatyviniai stiebai. Pagal morfologinius stiebų požymius visos keturios populiacijos skiriasi nedaug. Pagal absoliutųjį amžių daugiausia populiacijose buvo rasta antrų, trečių ir ketvirtų metų amžiaus stiebų, o mažiausiai septyniolikos, aštuoniolikos, devyniolikos ir dvidešimties metų amžiaus stiebų. Tirtose populiacijose morfologinių požymių kitimai priklauso tiek nuo amžiaus, tiek nuo populiacijos tankumo, tiek nuo konkurencijos bei skirtingų aplinkos sąlygų buveinėse... [toliau žr. visą tekstą] / Exotic are the plants originating from the lands and coming due to the human activity to the areas where they never grow before. One of these adventive plants is thicket shadbush (Amelanchier spicata). So, penetration of adventive plants is a continuous process associated with human activities, therefore it can be argued that the number of such plants in the country will continue to grow. Research of thicket shadbush (Amelanchier spicata) was carried out in July - September 2007-2008 in four different areas, namely Antaviliai, Aukštieji Paneriai, Žemoji Veržuva and Antakalnis. The area of 10000 m2 was chosen in each location. The area was then divided into 16 squares, and one square constituted 625 m2. When evaluating the morphological parameters of the ground parts of the plants, the height of stalks, the height to the first branch, the diameter was measured, and the absolute age and maturity age of stalks was determined. It was determined during the research that the densest was Antaviliai population. According to the maturity age groups the vegetative stalks were dominating in all analysed populations. According to morphological stalk features all for populations differ very little. By absolute age, the highest number of plants in the populations was with the second, third and fourth year stalks, and the least number was with stalks of seventeen, eighteen, nineteen and twenty year old. Changes of morphological features in analysed populations depend on age, on the density... [to full text]

This dissertation provides a capability creation perspective on the story of China’s technological catching up, or resurgence, if viewed from a broader historical perspective. Since the first Asian tigers caught up to modern technological standards (e.g., South Korea, Singapore), two schools of thought have dominated causal explanations (Nelson and Pack, 1999). The first perspective is the conventional accumulation approach, which attributes the major share of growth to the accumulation of physical and human capital, and views learning as a more-or-less automatic byproduct of those investments. The second perspective is the assimilation approach, which emphasizes the arduous learning, risk-taking entrepreneurship, and innovation that is involved in the process and argues that the former proposition neglects this aspect of the endeavour and may therefore lead to erroneous estimates. This dissertation focuses on the second school of thought. Compared to the first-tier Asian tigers, the second-tier tigers, of which China is representative, pose many challenges to the assimilation approach. First, the sheer size of the country results in an unusual scale and scope of activities and interactions in any field. Second, the long history of civilization in China suggests that many modern phenomena have historical roots that are unknown to outsiders and invisible and complex to insiders. The present study aims to contribute a small piece of the puzzle to our understanding of the big picture. By providing an in-depth study of the Chinese information and communication technologies (ICT) sector, this study explores changes that have occurred in the three key building blocks of capability creation; specifically, the sourcing, generation, and appropriation of technological knowledge. A qualitative case study approach was employed for the main, empirical part of the study, which consists of extensive firm-level interviews. Complementary statistical data, including patent data and historical archives, were used to provide context and a deeper look into the study topic. The results are described in five articles. The first article presents establishing overseas research and development (R&amp;D) laboratories as one of the major learning methods for overcoming disadvantages related to dislocation from technology sources and advanced markets. This approach allows China to search for industry-relevant scientific knowledge rather than adopting ready-made technologies introduced by western multinational enterprises in China. The second article describes the modularity-in-design approach, which opens new windows of opportunity for technological advancement. The lack of essential intellectual property rights (IPRs) acts as a key inducement and a factor-saving bias that influences the direction of innovation. When both (international) competitiveness and learning are involved in the catching-up process, the development of industry-wide capability becomes a particularly vital aspect of indigenous innovation. The third article describes the geographic consequences of historically planted industrial capabilities in China’s inland regions, which impact the absorption of different types of industrial knowledge. Fields of industry that are densely populated with patents- IPR thickets- represent a novel situation that was not experienced to the same extent by nations whose technological development occurred earlier. This thesis dedicates two articles to this dimension of knowledge appropriation. The fourth article describes the duality of Chinese ICT patenting, and the fifth article identifies an ambidextrous strategy that depends on where the major competition emerges. In general, the decision to patent and the extent of patenting are determined by four factors: a) the distance to the frontier (Aghion et al., 1997) particularly for technology; b) the nature of the technology (Teece, 1986), but with a rural extension in the case of China; c) the specificities of information (Arrow, 1962) that are embodied in a firm’s origins in China; and d) the supporting institutions that co-evolve in that process. Learning proceeds at different levels: that of individuals, firms, industries, and nations.   This dissertation provides an industry-level perspective on learning and innovation-based technological advancement. / from developing economy to global high-tech competitiveness - the case of Chinese ICT expansion