A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the Degree of Masters of Science by Coursework and Research Report. Johannesburg November 2017. / Mountains are complex environments owing to their varying topography and geographic range, and as a result are havens for a variety of eco-systems and biodiversity. Mountain systems around the globe are potentially transforming due to increasing pressure from human-driven climate change. The possible effects of these pressures and overall consequences of the changes are difficult to predict due to the complexity of mountain habitats. Previous studies have recorded increasing temperatures in mountain systems as one of the consequences of climatic change. As a consequence of this warming trend, plant species that typically grow in lower altitudes may migrate to higher altitudes as those habitats become suitable. There are many different effects this may have on the local eco-system, such as the possibility of the migrating species outcompeting the local species or even hybridization occurring, resulting in a new species. Regardless, the movement of species from low to high elevations will have a direct effect on plant community dynamics in the area. South Africa is experiencing warming temperatures and has experienced a reported increase in mean annual temperature by 0.96 ºC over the last five decades. This research aims to understand the implications of inter-annual temperature and precipitation trends in the alpine, upper and lower montane thermal zones in the Drakensberg on two endemic plant genera, Rhodohypoxis (Hypoxidaceae) and Glumicalyx (Scrophulariaceae). A thermal zone refers to a temperature gradient at a specific altitude in a mountain system. Temperature and precipitation data from 1994 to 2014 were collected from four weather stations: Sani Pass (2874 m), Shaleburn (1614 m) and Giants Castle (1759 m) in South Africa, and Mokhotlong (2209 m) in Lesotho. These sites represent three thermal zones; Sani Pass is in the alpine zone, Mokhotlong is in the upper montane zone, and Shaleburn and Giants Castle are in the lower montane zone. The objectives of this research are to analyse and compare the temperature and precipitation trends, inter-annual variability, and annual number of frost days at each data collection site from 1994 to 2014, as well as infer the potential impact these changes may have on the local endemic plant genera. Results show a more pronounced increase in temperature in the lower thermal zones and a larger decrease in precipitation in higher thermal zones. The lower montane zone experienced the highest increase in temperature of up to 0.6 ºC over two decades. The alpine zone showed the largest decrease in precipitation of on average 27.5 mm of rainfall per annum over 20 years, while the lower montane zone displayed the largest inter-annual variability in both temperature and precipitation variables. The upper montane zone had a larger decrease in frost days over the 20 year period relative to the lower montane zone. Interestingly this work showed an increased warming pattern in the lower thermal zones relative to upper zones, which contrasts with work in other mountain ecosystems. This warming may create larger intermediate regions which could encourage the movement of endemic flora into neighbouring thermal zones. Movement between thermal zones may increase hybridization within plant genera which could change the structure of the plant communities and possibly result in altered floral populations. Keywords: Climatic change, Drakensberg, endemic flora, thermal zones, temperature and precipitation trends, inter-annual variability / LG2018

Alpine soils are young, poorly developed soils that occur above treeline. This study investigates soils located in the alpine-subalpine zone of the Wallowa Mountains, northeast Oregon. Parent material, topography, and vegetation are the most influential pedogenic factors in the high alpine landscape of the Wallowas. Soil samples were collected from the Eagle Cap Wilderness Area of the Wallowas at three mountain locations: Eagle Cap, Sacajawea, and Matterhorn. Catenas were studied in the Windblown and Minimum Snowcover zones to examine different pedogenic factors, according to the Synthetic Alpine Slope model. · Field and laboratory testing characterized the alpine soils as predominantly loamy-sands with weak structural development. The 1:1 water pH values range from 6.5 to 7.3, and the soil hues are lOYR and 2. SY in color. Soil classification characterized Eagle Cap soils as Andisols: Lithic and Typic Haplocryands. The Matterhorn and Sacajawea residuum was not classified. Parent material influence on soil development was more noticeable on granodiorite than basalt, reflecting the propensity of granodiorite to weather rapidly. Marble and shale sites lacked soil development. All the soils exhibited eolian influence, determined from silt mineralogy results. While this component did not dominate the soils as in other alpine areas, its presence was ·proven by quartz and feldspars in soils developed on marble and calcite in soils developed on granodiorite. Sodium fluoride (NaF) pH tests indicate that there is also a high aluminum content in the alpine soils, probably due to influx of Mazama volcanic ash. Krummholz and alpine turf increase the organic content of the soil, although soils beneath krummholz were not as deep. This is partially due to decreased snowcover, subsequent lack of moisture, and different parent material. All soils show a decrease in organic carbon with depth indicating that bioturbation was either low, or the soil recovered from the disturbance rapidly. Organocutans found on the bottom of rocks in the B horizon illustrate organic trans location. The increase in pH with depth shows the influence of surficial organic matter, translocated dusts, and ash. Nunatak and landmass influence on soil development was undetermined.

Graduation date: 2003 / Presentation date: 2002-06-03

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

The Troodos ophiolite is a type example of ophiolite and has been studied for more than 50 years. Albeit numerous findings have been derived from previous investigations, some questions about the details of its formation processes are still outstanding. One of them concerns the origin of the pyroxenites in the mantle and the lower crustal section, and this is the main theme of this thesis. Integrated field, petrographical and geochemical work was conducted in this study. On the basis of distribution, the pyroxenites can be divided into two categories, crustal pyroxenites and mantle pyroxenite dykes. The results show that the layered or massive crustal pyroxenites can be distinguished by their magmatic features, and their formations have been controlled by a series of factors, including the melt composition, change of pressure, magma replenishment and magma mixing. The crystallization sequences of the crustal ultramafic unit samples are classified into two trends. Trend (i) olivine, orthopyroxene, clinopyroxene, plagioclase has been derived from tholeiitic-boninitic transitional melts, whereas trend (ii) olivine, clinopyroxene, plagioclase, orthopyroxene from depleted boninitic melts. Regarding the mantle section, the pyroxenite dykes have been formed by focused flow of melt during migration towards the crust. Data show that they are products of several processes, including melt-rock reactions and fractional crystallization. On the basis of modal composition, the pyroxenite dykes are divided into clinopyroxenites and orthopyroxenites. Geochemical compositions suggest that the clinopyroxenites have been derived from island arc tholeiitic melts, whereas the orthopyroxenites from boninitic melts. The important overlap of the tholeiitic and the boninitic series throughout the sections of the ophiolite, as well as the presence of lithologies with compositions transitional between the two series, suggests that the two magmatic suites existed together. A tectonic model of subduction initiation, during which the subducting slab rolled-back rapidly, triggering asthenospheric mantle flow into the mantle wedge, inducing partial melting at a shallow level of the mantle to generate a series of island arc tholeiitic magmas and at deeper level, a series of depleted boninitic magmas. The two magmatic series have possibly been mixed during migration in the mantle, producing transitional units of the two series. / published_or_final_version / Earth Sciences / Master / Master of Philosophy

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No description available.

No description available.

A wide area assessment of forecast changes in wintertime synoptic conditions over western North America is combined with a meso-scale alpine hydrometeorology model to evaluate the joint impact(s) of forecast climate change on snowpack conditions in an alpine watershed in the southern Canadian Rockies. The synoptic analysis was used to generate long-term climate time series scenarios using the CCCma CGCM1. An alpine hydrometerology model is used to predict changes in wintertime precipitation at the watershed scale. A mass balance snow model is utilized to predict the overall snow accumulation throughout a watershed. A vapour transfer model has been incorporated in the snow model to estimate snow volumes more accurately. The synoptic analysis and GCM output forecasts a modest increase in both winter precipitation and temperatures in the study area, resulting in a decline of winter snow accumulations, and hence an expected decline in spring runoff. / ix, 87 leaves : ill. ; 28 cm.

Graduation date: 1997