dr Olivier Jean Leonce Manzi
Will Central Africa’s forests withstand a warming climate?
African tropical forests have, so far, not shown the dramatic climate-driven dieback seen in the Amazon. But scientists are still uncertain whether this reflects true resilience, or whether these forests are simply yet to reach a critical tipping point.
For Dr Olivier Jean Leonce Manzi, a finalist for the 2026 Jennifer Ward Oppenheimer (JWO) Research Grant, answering this question is both an ecological and a social imperative.
“Climate change is already reshaping ecosystems, and tropical forests are among the places where those changes matter most,” he says, noting their role in regulating climate, storing carbon and sustaining millions of livelihoods. Yet, he points out a glaring blind spot in global conservation: much of the evidence on tropical forest responses comes from South America.
"In Africa, comparable datasets are sparse, geographically limited, and often generated by researchers based outside the continent," Manzi explains. "This means that some of the regions experiencing the fastest climatic change have the least empirical evidence on how their forests will respond."
His proposed research seeks to address this by examining how close African tree species are to their physiological limits under increasing heat and drought stress. Working with long-term forest plots across Central Africa, Manzi realised that while existing monitoring networks like AfriTRON are vital, they only tell half the story. “Plot data can show us that forests are changing, but not why particular species survive, grow or decline,” he notes.
To bridge the gap between detecting change and understanding its physiological drivers, Manzi’s project aims to generate the first continent-scale dataset on hydraulic and thermal thresholds for Central African tree species. This open-access dataset will link tree physiology, field observations and ecosystem modelling to definitively answer whether these forests are truly resilient or simply operating dangerously close to their physiological limits.
But for Manzi, the science is only part of the mission; the other is dismantling the structural hurdles African scientists face. During his PhD, severe administrative and visa issues left him stranded in Rwanda for almost a year, bringing his fieldwork and academic progress to a grinding halt.
“It was a stark reminder of the structural barriers that many African researchers still face, even when they are part of international research programmes and have done everything correctly,” he recalls.
Rather than defeating him, the setback reinforced his commitment to building supportive, Africa-led research networks. If awarded the JWO grant, he plans to use the resources to train the
next generation of African scientists, involving students directly in fieldwork, laboratory work and advanced modelling so they can collaborate without facing the same mobility barriers he did.
"Knowing that my research can strengthen local scientific capacity and inform better conservation decisions reminds me that science can have real impact beyond academia," Manzi says. "It motivates me to keep going, because the effort I put in today can help create better opportunities and a more resilient planet for those who come after us."
About the researcher
Dr Olivier Jean Leonce Manzi is a 33-year-old plant ecophysiologist and research fellow at the University of Rwanda. Manzi’s work examines how tropical forests respond to climate change, particularly the effects of heat and drought on tree physiology, resilience and carbon storage across African ecosystems.
Surprisingly, his journey into science was entirely unplanned; he originally intended to become a priest before discovering ecology by accident and realising how deeply forests matter for people’s lives. He notes that understanding and protecting African forests gives him a profound sense of purpose and desire to help make the world a better place for people and for nature.
His academic journey has required immense perseverance, and he credits his mentor, Dr Eric Dusenge Mirindi, for showing him that despite the limited resources and administrative barriers African researchers face, it is still possible to excel and contribute to world-class science. Working with Mirindi taught him the value of “resilience, discipline and scientific integrity” and proved that African scientists can lead important research on the global stage.
Having experienced his own severe administrative hurdles, such as a visa issue that stranded him in Rwanda for nearly a year and halted his PhD fieldwork, Manzi is deeply committed to breaking down these structural barriers. He hopes his research will not only inform conservation decisions but also strengthen local scientific capacity, building supportive, Africa-led networks so the next generation of scientists can collaborate freely.
2026 Jennifer Ward Oppenheimer Research Grant finalist Dr Olivier Jean Leonce Manzi is generating the first continent-scale dataset to understand how Central African tree species respond to heat and drought.