MSc Students

Nosipho Gqaleni

Department of Botany and Zoology

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Nosipho is studying the seasonal patterns of rainfall, soil moisture and related ecosystem water use efficiency in a semi-arid Nama Karoo landscape comprised of dwarf C3 shrubs and C4 grasses. Her study focuses on determining whether the soil moisture regime and related vegetation evapotranspiration response in the Eastern-Karoo is driven by rainfall seasonality or by specific rainfall events. She aims to describe the seasonal patterns of ecosystem evapotranspiration and determine the most efficient model to predict evapotranspiration from climatic data. She will also be developing a bucket model for this system to simulate soil moisture patterns at two depths. Her study intends to fill the knowledge gap about soil moisture regimes and ecosystem evapotranspiration in this semi-arid region.

Yenziwe Mbuyisa

Department of Botany and Zoology

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Yenziwe is an environmental scientist honours graduate from Rhodes University. Her interest in tree physiology and climate change have lead her to pursue a masters degree, in collaboration with Professor David Drew from the department of Foresrty and Wood science and the Eucxylo Group, looking at the effects of temperature and water availability on the water use efficiency and C isotopic discrimination of two myrtacea species, Eucalyptus grandis and Syzyguim guineense. This project is in response to the increasing movement of climate change mitigation through global tree afforestation/reforestation programs. With the likelihood of increasingly frequent and severe droughts and heat waves being a major cause for concern, understanding how trees respond to temperature extremes and limited water availability is critical to forecasting both short and long-term impacts of climate change on forest systems in South Africa.

Christopher Tonkin

Department of Botany and Zoology

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Eucalypts are some of the fastest growing and most productive trees. This could potentially make them a viable option for removing CO2 from the atmosphere and helping to mitigate the effects of climate change. However, the basis for their high productivity is not yet well understood but it has been noted that their productivity rates are often limited by drought conditions. Chris’ project is focused on studying the physiological processes of carbon uptake, biomass allocation and water use efficiency between a fast-growing varietal (Eucalyptus grandis x longirostrata) and a drought tolerant varietal (Corymbia henryii x torelliana) of Eucalyptus. He will further explore how temperature increases and drought conditions will affect these physiological processes in a semi-controlled greenhouse study.

Olivia Jones

Department of Botany and Zoology

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Olivia is in the first year of her Master’s Degree in Botany. Her research project “Megaherbivore trophic rewilding for top down herbivore control: A test-case in a semi-arid savanna.” will combine remote sensing techniques with field and lab data to investigate what impact megaherbivore rewilding has had on the vegetation structure in the semi-arid savanna region of Tswalu Kalahari Reserve, South Africa. This study will contribute to the field of trophic rewilding by providing the hypothesis testing and science-based monitoring approaches called for in the literature. It is pertinent that this study is being conducted in a savanna, as the ecosystem services provided by this biome are threatened by processes that have come about, in part, from loss of herbivore guilds, such as bush encroachment.

Aisha Rifai

Department of Botany and Zoology

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Aisha’s research project “Vegetation and predator-prey dynamics at the Tswalu Kalahari Reserve, in the South African savanna.” is an expansion of her honour’s project, which looked at the influence of lions on the vegetation productivity at the Tswalu Kalahari Reserve (TKR). But unlike the honour’s project, which was a complete remote study, this project will incorporate a hybrid approach consisting of remote sensing (RS) and fieldwork to assess the impact of predation by lions on vegetation growth. A 20-year period will again be investigated via RS methods. The RS portion will focus on environmental aspects, including vegetation index, drought index, fire and carbon influxes, and the changes in land use. The fieldwork will incorporate Landscape of Fear (LoF) modeling to quantify the effect lions exert on prey species. The main aim of this study is to statistically demonstrate the significance the presence of lions has on vegetation in a reserve. This information is vital in understanding the role predators play as ecosystem health indicators, and especially to reserves when reintroducing predators.

Kayleigh Murray

Department of Botany and Zoology

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Kayleigh Murray is a masters student in the Global Change Biology Group building a project that will use genomics to study historical range shifts of the climate change sentinel species Aloidendron dichotomum, or quiver tree. In collaboration with the Royal Botanic Gardens, Kew and the School for Climate Studies, this project will provide much needed insight into the health of quiver tree populations as temperatures increase across their range. Kayleigh is interested in streamlining species and ecosystem climate change response monitoring through the use of advanced genomics techniques and machine-learning computational modelling – methods that have been out of reach to institutions in the global south due to high cost and lack of training. Kayleigh hopes to make these methods more accessible for the advancement of conservation biology in Africa. Born in Gaborone, Botswana, Kayleigh gained their honours degree at Stellenbosch University, and recently finished their internship at the SU Botanical Garden.

Gaylen Carelse

Department of Botany and Zoology

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In her MSc project, Gaylen aims to assess the temperature tolerance of different life stages of the invasive coccinellid beetle, Harmonia axyridis. She examines how life stage-specific microclimates mediate the realized survival of a local population in semi-urban areas around Stellenbosch. Insects have fascinating, yet complex life cycles and the temperature tolerance of mobile stages, such as larvae and adults, are likely to differ from those of immobile stages, such as eggs and pupae. While temperature tolerance has been examined in many invasive insects, there is limited understanding of how temperature affects survival across life-stages in these species. Her study in the CL•I•M•E lab aims to increase knowledge of thermal tolerance throughout ontogeny in this invasive insect while considering the temperatures experienced in the field.

Gerhard Wiese

Department of Botany and Zoology

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Gerhard is a MSc student within the CL•I•M•E research group focusing on lizard physiology, specifically temperature effects on their rates of water loss. Using flow-through respirometry he is measuring the amount of water vapor expelled through the skin and the respiratory system of the lizards. He is also aiming to determine how the partitioning of water loss differs with increasing ambient temperatures. Physiological studies, such as those measuring the temperature sensitivity of water loss rate, are important for understanding how these organisms respond to environmental conditions experienced in nature. Relating these water loss rates to temperature and body size will provide key information for enhancing predictive mechanistic models of vulnerability of lizards to climate change.