Royal Museum for Central Africa

In mountainous regions, intense rainfall can trigger thousands of landslides within hours. The drivers that control the occurrence of such landslides, and the methods for predicting the zones susceptible to their initiation have been extensively studied. Yet, for many of the most severe disasters associated with these landslide events, the main impacts on local communities occurred far from the source areas where most modelling efforts are focused. Sediments mobilized high on slopes by rainfall-triggered landslides can be transported many kilometres downstream, causing significant impacts along their path, while also feeding river systems with large amounts of sediments and consequently increasing flood risks. Such chain of cascading hazards significantly increases the destructive potential of landslides as well as their impact zone. Effective risk mitigation must therefore address not just susceptibility to initiation but also landslide mobility and hazard interactions – yet such studies remain rare. With this work, we emphasize the importance of capturing what we refer to as the landslide–debris-rich flood continuum (landslide source, runout and related debris-rich floods) for accurate inventory, susceptibility and exposure mapping when landslide mobility is high – as it is often the case for extreme rainfall events. We apply this approach in two districts of eastern Zimbabwe (> 8000 km2), severely impacted by Cyclone Idai in March 2019. Using simple, replicable methods, we mapped over 14 000 (mostly) shallow landslides and 94 km2 of debris-rich flood-affected zones. These data informed detailed susceptibility and exposure models that distinguish between the processes involved. Our results show that around 226 000 individuals live in areas of moderate to high susceptibility to landslide or debris-rich floods – closely matching official figures of those affected by the cyclone. Notably, landslide sources account for only about one-fifth of this total exposure. This highlights the need to consider the entire hazard continuum. Our approach also exemplifies how simple, open-access tools and data can be highly effective for hazard and risk analyses across of the globe.

The Karagwe-Ankole Belt (KAB) in the Great Lakes region of Central Africa comprises metasedimentary stratigraphic units, metamorphic complexes and magmatic intrusions mainly of Mesoproterozoic age, but also hosts Paleoproterozoic and Neoproterozoic rocks. The Mesoproterozoic units are relatively well known in Rwanda, and, to a lesser extent, in Burundi, where they have been mapped at the 1/100.0000 scale. Instead, in the Kivu and Maniema regions of eastern DRC, they are known locally but in disconnected areas and detailed geological maps are not available.Based on recent investigations in Kivu and Burundi, together with new insights from the revised geological map of Rwanda, this paper reexamines the geological evolution of the Kivu region by proposing new lithostratigraphic correlations between the Eastern and Western sides of Lake Kivu. East of the lake (in Rwanda & Burundi), the Mesoproterozoic formations are assembled in the Akanyaru Supergroup, and West of the lake (North and South Kivu, DRC), in the Kivu Supergroup. The Neoproterozoic Itombwe Supergroup, well defined in Kivu, is also present in Rwanda, showing that its extension is not limited to the Itombwe ‘syncline’, and it was deposited over a wider region.The present paper also revises the geochronological framework based on recently published and new 40Ar/39Ar and U-Pb ages. Altogether, we propose an updated chronology for the stratigraphic, magmatic, metamorphic and tectonic evolution of the Karagwe-Ankole basin from Rodinia amalgamation and breakup to Pan-African reactivations.

Introduction: Agroecological farming has emerged as a promising approach for managing crop pests, including the 'true' fruit fly (Diptera: Tephritidae), in cucurbit production. Cucurbits are importantfor both nutrition and income generation, making effective pest management critical to ensure sustainable yields and improved farmer livelihoods. Despite the growing promotion of agroecological practices as alternatives to synthetic pesticides, evidence on their economic benefits remains limited. Methods: This study was conducted in Morogoro Region, Tanzania, through field experiments, to compare the economic impacts of agroecological and conventional management practices in cucurbit crop production. Discussion: Results showed that management practices significantly (P < 0.05) influenced both marketable fruit weight and production costs. For squash, agroecological plots yielded significantly higher marketable fruit weights compared to conventional plots, while for watermelon and cucumber, yields were comparable across the two practices. Production costs were consistently higher under conventional management for all three cucurbit crops. Furthermore, the net profit and cost-benefit ratio were significantly higher (P < 0.05) in agroecological systems. Conclusion: The findings indicate that agroecological pest management presents significant economic benefits compared to conventional methods. This approach offers a sustainable and cost-effective alternative for reducing reliance on synthetic pesticides in cucurbit production systems and agriculture.

Secondary forests are becoming an increasingly dominant component of tropical landscapes. They play a critical role in the global carbon cycle by removing atmospheric CO 2 during regrowth after disturbance. Yet, their capacity to sequester carbon and the time needed to recover carbon stocks comparable to those of nearby old-growth forests remain poorly understood – particularly in sub-Saharan Africa, where forest clearing for smallholder agriculture is accelerating. Here, using ground-based data from 983 secondary forest plots across 32 sites in 12 African countries, we show that natural regeneration delivers substantial aboveground carbon gains within the first two decades (11–109 Mg C ha -1 ). These gains are substantially overestimated unless remnant biomass left on abandoned fields is accounted for. The median time to recover 90% of old-growth carbon stocks ranged from 36 to 92 years across sites, albeit with considerable uncertainty. Early carbon accumulation followed identifiable environmental gradients – increasing with precipitation, whereas the time needed to reach old-growth stocks decreased with the maximum climatic water deficit and remained poorly predicted. By combining field-derived biomass recovery trajectories with spatial environmental predictors, we map carbon recovery potential across Afrotropical secondary forests. Because full carbon recovery takes many decades – far longer than the timescales required to meet global climate targets by 2050 – secondary regrowth cannot reliably compensate for the loss of old-growth carbon, making the conservation of remaining old-growth forests essential.

Schistosomiasis, a neglected tropical disease, affects people of all genders and ages. However, few studies have examined how communities in endemic areas perceive gender roles as factors influencing infection and control. This study explored the perceptions of farming (Kyaterekera) and fishing (Ndaiga) communities along Lake Albert in Uganda's Kagadi District regarding gender roles and their role in schistosomiasis infection. Using an ethnographic design, we conducted 10 key informant interviews and 18 focus group discussions with 150 participants. Data were analysed thematically. Participants from both settings recognised that gender roles influence infection risk differently for men and women. Societal expectations and gender stereotypes were seen as contributing factors. Farming men often perceived bilharzia as a lake-side issue. Drug side effects were a shared concern, but women in fishing communities preferred using herbs and prayers, while men favoured hospital visits. Gender roles and perceptions of schistosomiasis risk vary by gender and location. Common themes include societal expectations, stereotypes and concerns about treatment. Gender-specific interventions, such as gender-sensitive campaigns and inclusive decision-making, could help effectively control the disease.