dr Marc Van Goethem
Reading the soil before the desert arrives
Across Africa’s drylands, the signs of desertification are usually recognised only after they become visible.
Vegetation thins out. Bare patches of soil expand. Water becomes harder to retain. By then, restoring degraded land can take years and require substantial investment.
For researcher Marc Van Goethem, a finalist for the 2026 Jennifer Ward Oppenheimer Research Grant, the challenge is not simply understanding desertification. It is detecting it before these visible changes begin.
His proposed research starts beneath the surface, among the microbial communities that live in the soil.
These microscopic organisms play a role in nutrient cycling, water retention and the processes that help ecosystems function. According to Van Goethem, they may also provide an earlier indication of environmental stress than the plants growing above them.
The project, titled Invisible Sentinels: Predicting Desertification Tipping Points Using Microbial Functional Signatures Across African Drylands, seeks to investigate whether changes in microbial communities can reveal when an ecosystem is approaching a critical threshold.
To answer that question, Van Goethem plans to study soils across some of Africa’s major dryland regions, including the Kalahari, Namib, Sahel and Sahara. Rather than focusing on which microbial species are present, the research will examine how well these communities continue to perform functions linked to ecosystem health as environmental stress increases.
Using genomic sequencing and computational modelling, the project aims to identify points at which microbial systems begin to lose their capacity to support key ecological processes. The underlying hypothesis is that these biological shifts may occur before vegetation decline becomes visible.
If such thresholds can be identified, the research could contribute to the development of a new monitoring tool. Van Goethem proposes creating a Functional Resilience Index that would indicate how close an ecosystem is to ecological collapse.
The long-term goal is to provide land managers, conservation agencies and governments with earlier warning signals than those currently available through conventional monitoring systems.
In practical terms, this could allow interventions such as grazing management, restoration efforts or water conservation measures to be implemented before degradation becomes difficult to reverse.
At a time when climate change and water scarcity are placing increasing pressure on dryland ecosystems, the project asks whether some of the earliest warnings of desertification may already exist beneath our feet.
The question is whether scientists can learn to read those signals in time.
About the researcher
Dr Marc Van Goethem is a 35-year-old microbial ecologist at the University of Pretoria. His research explores how microbial communities adapt to extreme environments, from Antarctic deserts to hyper-arid drylands, and how these microorganisms can contribute to ecosystem restoration and resilience in a changing climate.
His fascination with these harsh environments began in childhood. Growing up, he frequently wondered why deserts were so vast in Africa compared to other continents. He would ask himself, “Will deserts continue to expand? What is the lifespan of a desert?” This curiosity ultimately drove his professional career to study the ingenious ways plants, animals and microorganisms survive persistent heat and water stress.
Van Goethem’s academic journey has spanned Belgium, the United States of America and Saudi Arabia, exposing him to world-class supercomputing facilities. Returning to South Africa’s more limited infrastructure could have been a frustrating setback, but it instead forced him to become highly efficient, designing collaborative experiments to maximise the resources at his disposal. He credits his mentor, Prof. Thulani Makhalanyane, for shaping his understanding of what it means to be a researcher and championing science communication.
Outside of his research, Van Goethem is an avid chess player, indoor wall climber and proud father. He also enjoys cooking with his wife, Amy, which he jokes keeps his “wet lab skills” current, and grows Portulacaria afra (spekboom) at home, with his oldest plant now being 18 years old. And his son, Mateo, now four years old, often wakes him up at 5 a.m. with maths questions and dreams of becoming a scientist.
2026 Jennifer Ward Oppenheimer Research Grant finalist Marc Van Goethem is investigating whether soil microbes can provide early warning signals of desertification across Africa’s drylands.