Team - ARCHIBALD ECOLOGY LAB

SALLY ARCHIBALD

I work on understanding the dynamics of savanna ecosystems in the context of global change. My work integrates field ecological data, remote sensing, modelling, and biogeochemistry. I am involved in collaborative research projects with Yale University, Edinburgh University and the University of Liverpool among others which variously work on fire-grazer interactions, inter-continental savanna comparisons, the importance of land-atmosphere feedbacks, and pursuing a global theory of fire. I am closely linked with research projects at the Global Change and Ecosystems group at the CSIR where I hold an affiliate position.

current students

Jess Rickenback - Doctor of Philosophy Candidate
I am a PhD student at the University of Edinburgh and the Royal Botanic Gardens Edinburgh, UK. My research focuses on the ecology, biogeography, and evolutionary history of tropical grasslands. These diverse ecosystems are vulnerable to policies of afforestation and fire suppression.

Humbelani Thenga - Doctor of Philosophy Candidate
My Research explores the impact of woody plant encroachment (WPE) on soil organic carbon (SOC) in savanna systems with a focus on fundamental questions of: How does WPE affect SOC in magnitude and direction? How litter quality, edaphic factors (e.g. soil physicochemical properties and moisture) and changes in micro-environment (temperature and microbial diversity) mediate these effects? This study will allow us to address some of the burning questions on the role of WPE in sequestering carbon. There is a growing consensus derived from satellite monitoring technique, which suggests that WPE in dry and semi-arid lands is a good nature-based solution for sequestering atmospheric carbon. The major challenge to this simplistic linear thinking is that there is lack of understanding on the mechanisms driving the Net carbon sequestration (plant + soil) and the sustainability of this carbon pool under changing climate compared to that of grasses, which are reportedly more resilient to climate extremes.

Caroline Mashau - Doctor of Philosophy Candidate
My research interests cover evolutionary history (phylogeny) and ecology of grasses in Africa. The aim of my project is to understand the range size and dispersal of grasses in Africa with the purpose of quantifying differences between genera and functional types and determining the floral traits that are associated with fire and grazing. I will assess how plant height, evolutionary history and lifespan drive range sizes, and whether this can help to explain which grass species have become invasive outside their native ranges. I am working under supervision of Prof. Sally Archibald and co-supervised by Dr Caroline Lehmann from University of Edinburgh (UK) and Dr Maria Vorontsova from Kew Herbarium (UK).

Mthokozisi Moyo - Doctor of Philosophy Candidate
My project focuses on the ecophysiological and biogeographical evidence for the onset of wet-dry seasonality in Africa. The aim of my project is to detect when wet-dry seasonality began in Africa in the late Miocene. I am also looking at the traits that are important for plants and animals to survive in seasonal environments. I will use past fossil records and other paleobotanic evidence to see when these traits evolved in the past. These traits will be used with phylogenetic and paleo-ecological data to test alternative hypotheses on the timing of the spread of seasonally arid systems in Africa. Lastly, I am interested in creating a model of all the factors that control seasonality in Africa. With a changing climate, understanding how plants responded to changes in the past will help us to understand how they may change in the future.

Evalt Lebese - Master of Science Candidate
I am currently doing my MSc under the supervision of Prof Bob Scholes and co-Supervision of Prof. Sally Archibald and my interest lies in the growth response of plants to rising temperatures and elevated Carbon Dioxide as a result of Global Change. It has recently been noted that the tree Leucosidea sericea is encroaching into formerly treeless high-altitude C4-dominated grasslands of the eastern escarpment; the expansion of high-altitude patches of the C3 grass Festuca costata has also been observed. Could these observations be explained to be due to rising CO2, rising temperature, both, or an interactive effect? To try to answer these questions, my MSc research is set out to test the effect of elevated CO2 and rising temperatures on Themeda triandra (C4 grass), Festuca costata (C3 grass) and Leucosidea sericea.

Londiwe Mokoena - Master of Science Candidate
Becoming a biologist came natural to me, although I strayed at some point but my heart has always been linked to biology from an early age, I find my interests to be vary from global change and sustainability to ecosystem resilience and fire pattern in Savannas. I completed my degree in biological sciences in 2018 at Wits University and I am currently doing my honours degree in Animal, Plants and Environment. My project is on the different drought strategies of perennial C4 grasses in South Africa and how that links to flammability. The project is supervised by Prof Sally Archibald.

Edith Singini - Doctor of Philosophy Candidate
My research interests include climate change ecophysiology and ecology of C3 and C4 plants in savanna ecosystems. For my PhD, I am working with Sally, Brad Ripley (Rhodes University) and Colin Osborne (University of Sheffield) to assess how C3 tree seedlings and C4 grasses respond differentially to water availability and elevated CO2 and how this changes across a rainfall gradient. This will help us understand the interaction between elevated CO2 and water availability as global drivers of woody plant encroachment.

Célia Gomes - Doctor of Philosophy Candidate
I am a PhD student at FCUP/CIBIO-InBIO - Faculty of Sciences of the University of Porto/Research Center in Biodiversity and Genetic Resources, Portugal. My main interests are wildlife and ecosystems' conservation and applied ecology.
I am working under the supervision of Dr Martim Melo (CIBIO-InBIO & Percy FitzPatrick Institute of African Ornithology) and co-supervised by Professor Sally Archibald. The aim of my project is to understand the impact of fire on Angola's Afromontane forests. The objectives are to determine de state of Angola's Afromontane forests, review their importance for conservation and, for the first time, provide a clear picture of the impact that fire has on them. The data to address the objectives of this project will be collected along to main axes: 1) analysis of the role and physical impact of fire on the remaining Afromontane forests of Angola and 2) ecological studies evaluating the impact of fire on forest-dependant biological communities (forests' seed banks and birds).

postdoctoral fellows

Gareth Hempson
My research interests lie in understanding how large mammal herbivores and fire shape vegetation patterns, and vice versa. For my current postdoc in the Archibald Lab, I am collecting field data to understand how grass traits and life histories are distributed across broad environmental gradients in both burned and grazed landscapes. This will allow us to test ideas on how ecosystem drivers and potential ecosystem states vary across these gradients, how communities are assembled, and to delve into the evolutionary history of these ecosystems. This has important implications for managing fire and grazers in these grassy ecosystems, with consequences for food security, sustainability, biodiversity, tourism – and more!

Monique Botha
I have a keen interest in the determinants of woody vegetation structure and function in savanna systems and the factors affecting grassland-savanna boundaries in South Africa. My work currently focuses on assessing the response of savanna and forest tree seedlings to fire, frost, herbivory and shading, which have been recognized as major limiting factors to tree seedling establishment and persistence in open grassy systems.

Chao Wu
I am interested in fire modeling and how fire-induced biogeochemical cycles respond to climate change. I received my dual PhDs from Tsinghua University and University of Exeter where I studied wildfire dynamics and the impacts of fire on the global carbon cycle, vegetation distribution, and feedbacks to the climate system. Working with Sally and Carla Staver (Yale), I will use remote sensing and numerical simulation methods to improve global fire models, specifically in their representations of fire size and duration to better understand extreme fires.

Anabelle Cardoso
I am interested in the ecology of savanna ecosystems, specifically in fire-vegetation interactions and the landscape-scale drivers of fire behaviour. I received my PhD from The University of Oxford where I studied how fire and forest elephants affect forest-savanna boundaries in a mosaicked landscape in Gabon in Central Africa. I am currently a postdoc in the Archibald lab, and jointly appointed by Yale University in the lab of Carla Staver. During my postdoc, I am working on modelling the processes determining fire size distributions, and specifically investigating the limitations to fire spread.

Mathieu Millan
My research interests lie in understanding the mechanisms underlying plant growth forms and how they influence plants performance in different ecological contexts. I joined the Archibald Lab to work with Nicola Stevens (Oxford), Sally and Guy Midgley (Stellenbosch University) on landscape sterility and ontogenetic dead ends in the Lowveld region. My research focuses on the relationships between tree architecture, developmental stage and flowering ability in common savanna tree species. I’m trying to understand how high disturbance regimes (both in the past and present) influence tree saplings’ ontogeny and architecture and its consequences in terms of population dynamics.

Past students and Postdoctoral Fellows

Busisiwe Jaxa (Hons) 2020 - 2020: Currently a MSc student at the University of the Witwatersrand
Emma Wright (Hons) 2020 - 2020: Currently a MSc student at the University of Cape Town
Tamryn Hamilton (PhD) 2018 - 2020: Currently a PhD candidate at the North West University
Caitlin Ransom (MSc): Currently an intern at SAEON
Dylan Beukes (MSc) 2017 - 2019: Currently an NRF intern at the University of Pretoria
Swanni Alverado (Postdoc) 2018 - 2018: Currently a postdoctoral research fellow at Universidade Estadual do Maranhão
Margaret Parrish (MSc) 2017 - 2018: Currently a data manager at Indigo Consulting In Santa Fe
Michael Voysey (MSc) 2017 - 2018: Currently a PhD candidate at Harvard University
Liakae Ramasimong (MSc) 2017 - 2018: Currently working as a consultant
Jason Donaldson (PhD) 2015 - 2015: Currently a postdoctoral fellow at Wake Forest University
Felix Skhosana (MSc) 2015 - 2016: Currently a PhD studentship at the CSIR
Basand Nondlazi (MSc) 2012 - 2016: Currently a PhD studentship at the CSIR
Zoey Luhdo (MSc) 2013 - 2015: Currently a reserve manager at Stevensford Game Reserve
Nthambeleni Masia (MSc) 2012 - 2015: Currently a senior research technician at Agricultural Research Council in Mpumalanga
Drew Pollard (MSc) 2013 - 2014: Currently a reserve manager at Karingani Game Reserve
Melissa Howes-Whitecross (PhD) 2012 - 2014: Currently a program manager at BirdLife International
Sajith Vezhapparambu (Postdoc) 2012 - 2013: Currently a researcher at Amrita University

ADMINISTRATION assistant

Thando Twala
My research interests include ecological biogeography and ecophysiology of savanna and forest tree species. I am currently working towards my PhD with Dr Jolene Fisher and Dr Kelsey Glennon in order to investigate and highlight how environmental factors, dispersal and physiology influence the distribution of South African podocarps. This will enable us to understand how South African podocarps are able to persist in their current distribution and to predict how they will respond to climate change.
In addition to my research, I am working with the Archibald lab as an administration assistant trying to make sure the lab runs smoothly.

affiliates

Dr Caroline Lehmann

Prof Kate Parr

Dr Nicola Stevens

Dr Abraham Dabengwa

Field technicians

Happy Mangena
Amanuel Abraha