This dissertation grew from an investigation of the farm Doornkloof in Irene, Pretoria. The farm was home to General Jan Smuts and it is here that he wrote his seminal philosophical work “Holism and Evolution” and found his own grass specie Digitaria Smutsii. The theoretical investigation is rooted in the interpretation of Holism, as an architectural theory, which informs the proposed design intervention. This study is informed by an analysis of the area of Irene, its origins and its future growth lead to the development of a holistic framework. This study proposes to inform the future socio-economic and historical importance of the farm as open public space for the citizens of Tshwane and Irene. The research intervention proposes a new architectural programmatic typology that will celebrate the importance of the Bankenveld landscape. The systematic rehabilitation of the grassland landscape will be achieved by introducing small scale interventions. The series of design interventions will rehabilitate the existing historical layers of the site, create new interest in the farm, improve the economic position of the Jan Smuts Foundation (the owners of the farm) and protect the landscape for the future generation users. / Dissertation MArch (Prof)--University of Pretoria, 2012. / Architecture / unrestricted

The coastal ocean is a marginal region of the global ocean, but is home to metabolically intense ecosystems which increase the structural complexity of the benthos. These ecosystems have the ability to alter the carbon chemistry of surrounding waters through their metabolism, mainly through processes which directly release or consume carbon dioxide. In this way, coastal habitats can engineer their environment by acting as sources or sinks of carbon dioxide and altering their environmental chemistry from the regional norm. In most coastal water masses, it is difficult to resolve the ecosystem effect on coastal carbon biogeochemistry due to the mixing of multiple offshore end members, complex geography or the influence of variable freshwater inputs. The Red Sea provides a simple environment for the study of ecosystem processes at a coastal scale as it contains only one offshore end-member and negligible freshwater inputs due to the arid climate of adjacent land. This work explores the ability of three Red Sea benthic coastal habitats (coral reefs, seagrass meadows and mangrove forests) to create characteristic ecosystem end-members, which deviate from the biogeochemistry of offshore source waters. This is done by both calculating non-conservative deviations in carbonate stocks collected over each ecosystem, and by quantifying net carbonate fluxes (in seagrass meadows and mangrove forests only) using 24 hour incubations. Results illustrate that carbonate stocks over ecosystems conform to broad ecosystem trends, which are different to the offshore end-member, and are influenced by inherited properties from surrounding ecosystems. Carbonate fluxes also show ecosystem dependent trends and further illustrate the importance of sediment processes in influencing CaCO3 fluxes in blue carbon benthic habitats, which warrants further attention. These findings show the respective advantages of studying both carbonate stocks and fluxes of coastal benthic ecosystems in order to understand the spatial, temporal and net effects of their metabolism on the coastal ocean.

The overall goal of the thesis was to study available geographic information systems (GIS) and to explore the functionality they provide. The implementation was focused on module for vector data creation and data analysis. As examples were used existing systems like GRASS and ArcGIS. The result of this master thesis was a plug-in integrated into the GIS of DELINFO, spol. s r.o. company. The plug-in can open, modify and save vector data in shapefile format. The plug-in is also able to do some basic analysis of the vector data, such as a region intersection, a union, hit tests and a distance measurement. This thesis could be used as a pattern for vector data operations in GIS.

The Greater Cape Floristic Region (GCFR) of South Africa has one of the most biodiverse floras in the world. Although ecological speciation is thought to be a primary mechanism behind diversification in the GCFR, it has recently been hypothesised that non-ecological speciation may have an influential role in driving diversification in the montane “sky islands” of the GCFR, potentially resulting in cryptic species. This work seeks to test the relative importance of ecological versus non-ecological processes in powering speciation at different elevations in the GCFR, and to assess the existence of multiple, range-restricted cryptic species at high elevations. The Cape grass genus Ehrharta is an ideal system in which to investigate these processes, as it contains low-, mid-, and high-elevation lineages, with a previously documented adaptive radiation in the succulent karoo. Population-level phylogenetic analyses using targeted enrichment sequencing data show that E. rupestris and E. setacea, as currently defined, are polyphyletic, and reveal multiple distinct monophyletic lineages within the Ramosa, Rehmannii and Setacea clades of genus Ehrharta. Analysis of genotyping-by-sequencing and morphological data, together with evidence of sympatry, confirm these lineages to be distinct entities, resulting in 13 to 16 putative new species, of which several can be considered cryptic. The crown node of Ehrharta is found to have originated 28 Ma, which substantially antedates previous age estimates. Comparisons of morphological evolutionary rates, as well as rates of nonsynonymous to synonymous sequence evolution (��), provide little evidence to support the hypothesis that non-ecological processes have been more important at high elevations. Both the low- and high-elevation clades show evidence of divergent ecological selection, with the Lowlands clade exhibiting high functional trait variance, and the high-elevation Setacea clade showing subtle ecological differentiation and accelerated rates of morphological evolution and �� relative to the rest of Cape Ehrharta. It is instead suggested that diversification in the Cape Ehrharta is triggered by a combination of intrinsic and extrinsic factors unique to each clade, thus corroborating a growing body of research arguing that it is simplistic to generalise radiations as ‘adaptive’ or ‘non-adaptive’. Instead, mountain radiations require an integrated approach to untangle the subtle interaction of geographic, ecological and biological factors that drive diversification.

Continental scale analysis of the savanna biome indicated that fire did not spread at tree canopy cover above 40%. This study investigates this relationship in a field study. It is possible that the type of tree (forest vs. savanna) may influence the amount of shade experienced by the understory and therefore this study also explores differences in LAI between congeneric pairs of forest and savanna tree species. Data were collected in two major South African savanna parks. Plots were set out to measure grass biomass in reference to canopy cover in both Kruger National Park (n=60) and the Hluhluwe-iMfolozi Game Reserve (n=82). Seven congeneric pairs were selected to compare leaf area and LAI between forest and savanna tree species using a destructive method. Against expectations, it was only when canopy cover reached 80% that grass fuel load was too low to support fire spread in all Kruger National Park plots (Pr=O) and 89% of the Hluhluwe-iMfolozi Game Reserve plots (Pr=0.11). No consistent, general relationships were evident with leaf area or LAI in comparisons between forest-savanna congeneric pairs. The significance of these findings and future direction is discussed.

Kikuyu (Pennisetum clandestinum) is highly productive during summer and autumn and capable of supporting high cattle stocking rates., The winter and spring production of kikuyu, however, is low, while forage quality, and consequently milk production per cow, is also low compared to temperate grass species. The aim of this study was to determine the dry matter yield, botanical composition, nutritional value, grazing capacity and milk production potential of irrigated kikuyu over-sown with Italian ryegrass (Lolium multiflorum var. italicum), Westerwolds ryegrass (Lolium multiflorum var. westerwoldicum) or perennial ryegrass (Lolium perenne) under an intensive grazing system with Jersey cows. Calibrations for the rising plate meter (RPM) were developed for the kikuyu-ryegrass systems. These calibrations were evaluated for seasonal variation, linearity and were also combined over seasons, treatments and years to develop a calibration equation that could be used by dairy farmers in the region. The three kikuyu based pasture systems reached their peak growth rates during different months and seasons. All treatments experienced lower growth rates during winter, while peak growth rates occurred during spring for the Italian ryegrass treatment; summer for the Westerwolds ryegrass treatment and late spring/early summer for the perennial ryegrass treatment. All three treatments had similar total annual dry matter yields (kg DM ha-1) during the first year of the study. However, during year 2 the PR treatment had a higher annual DM production than IR and WR treatments. The ability of the PR treatment to maintain DM production during periods when the other treatments underwent a dip in production (WR during spring and IR during summer) enabled the PR treatment to maintain a higher annual DM production during year 2 than the systems based on annual ryegrass species. As the kikuyu component increased in kikuyu-ryegrass pastures from winter to summer, the DM and NDF content increased, while the ME content decreased. All three treatments were deficient in Ca throughout the study and deficient in P during summer and autumn for high producing dairy cows. The Ca:P ratio was below the recommended ratio of 1.6:1 for high producing dairy cows throughout the study. The grazing capacity of all three kikuyu-ryegrass systems was lower during winter and autumn than during spring and summer. The seasonal grazing capacity of the perennial ryegrass treatment, however, was more evenly distributed than that of the Italian and Westerwolds ryegrass treatments. The perennial ryegrass treatment had a lower butterfat and milk production per lactation than the Italian and Westerwolds ryegrass treatments during both years, but had the highest milk production per ha. The latter was a result of the higher annual grazing capacity achieved by the perennial ryegrass treatment. It was thus concluded that, because kikuyu over-sown with perennial ryegrass supported a higher number of animals and had a more evenly distributed fodder-flow, it allowed for higher animal production per ha than kikuyu over-sown with annual ryegrass varieties such as Italian and Westerwolds ryegrass. The pre-grazing and post-grazing regressions of all three the kikuyu based pastures developed for the RPM differed over seasons and years, primarily due to the change in botanical composition from ryegrass based pastures during winter to kikuyu-based pastures in the summer and the associated change in pasture structure. The post-grazing regressions developed during the study did not have a lower degree of accuracy (R2 values) than the pre-grazing regressions. The generalised RPM regression equations developed for kikuyu-ryegrass pastures (consisting of large data sets pooled over treatments and years) could be of use to farmers in the surrounding area, but are not recommended for research purposes due to the large errors and variation associated with such regressions. In the event that farmers employ these calibrations it is important that pasture type and pasture management practices be similar to those utilised during the study. The decision on which kikuyu-ryegrass system to utilize should be based on the specific conditions prevalent on a particular farm, an economic analysis on and a comparison between the three systems, as well as the particular fodder-flow program requirements within the pasture system. / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

Understanding the carbon cycle of major ecosystems is important in predicting feedback responses of the terrestrial biosphere to climate change. Bromus tectorum dominated ecosystems currently cover 7% of the Great Basin and represents a major land cover type for the region. This study looked at the carbon cycle of a near monoculture field of B. tectorum in southeastern Idaho, USA. A major portion of the study was dedicated to measurement validation because of the disagreement among techniques used to measure net ecosystem exchange (NEE) of CO2 between the atmosphere and terrestrial ecosystems . NEE, net photosynthesis, and canopy and soil respiration were quantified for the B. tectorum stand using multiple methods. This allowed for comparisons among measurement techniques and permitted the calculation of a best estimate of NEE. The study found that the eddy covariance technique underestimated NEE at night for the B. tectorum stand and the magnitude of underestimation increased with increasing leaf area index of the plant canopy. Annual NEE estimated by eddy covariance for the year 2005 was over four times lower than the best estimate of -80 g C m-2 yr-1 determined by a combination of methods. Implications are that many studies currently underestimate NEE and productive systems underestimate NEE more than less productive systems.

The influence of the spatial pattern of foliage removal on regrowth was investigated in the field with a tussock grass, Agropyron desertorum. Tussocks were hand clipped in different spatial patterns that represented extremes of defoliation patterns which could be inflicted by natural herbivores. All defoliated tussocks exhibited increases in specific growth rates following clipping in mid-May. When foliage was removed from the upper portion of the canopy (younger foliage), regrowth rates and season-long aboveground biomass production were less than if the same amount of foliage was removed from low in the canopy (older foliage). The spatial pattern of defoliation also influenced tussock regrowth in a late-May clipping experiment, but differences in the effects of the clipping patterns were associated with the removal of apical meristems rather than with the age or location of foliage removed. Changes in tussock carbon dioxide and water vapor exchange that were associated with changes in growth following mid-May clipping were explored. All clipped tussocks showed increases in integrated daytime carbon dioxide uptake per unit foliage area after defoliation. Differences among treatments in the response of net daytime carbon gain during the first 24 hours after clipping corresponded well with differences in tussock regrowth over a 14-day period following clipping. Increased carbon gain of clipped tussocks was associated with increases in tussock water vapor conductance and intercellular carbon dioxide concentration, and decreases in the ratio of carbon dioxide uptake to water vapor loss. Differences among treatments in daytime carbon gain and regrowth were paralleled by the response of instantaneous rates of light-saturated net photosynthesis for entire tussocks. Defoliation increased the proportion of foliage directly illuminated within the tussock at solar noon. Changes in the fraction of sunlit foliage and the relative amounts of different-aged foliage in tussock canopies were correlated with the responses of light-saturated photosynthesis. Thus, the effects of the spatial pattern of foliage removal on canopy light microclimate and the age of remaining foliage had important implications for carbon gain and regrowth of tussocks following mid-May defoliation.

The objective of this study was to evaluate the nutritional profile of mono- or multi-species pastures of native warm season grasses. One of four treatments were randomly assigned to Twelve pastures: 1) BG; 2) IG; 3) Mix G; 4) Mix NG. Growing steers (n = 225) were randomly assigned to one of nine pastures. Grass samples were taken from all pastures every 28 days during a four-month period and were analyzed for nutrient composition. Bermudagrass pastures had greater crude protein and ADF, but less NDF concentrations compared with the native warm-season grasses. Crude protein, IVDMD, and NDF IVDMD concentration decreased while NDF, ADF, and Hemicellulose concentration increased as grasses matured. Steers grazing IG and Mix G pastures gained more weight and consumed more forage than those on BG pastures. It appears that native warm-season grasses may offer a viable alternative to BG for grazing cattle during the summer.

No description available.