Aerosolized particulate matter (PM) is a complex mixture that has been recognized as the greatest cause of premature human mortality in low- and middle-income countries. Its toxicity arises largely from its chemical and biological components. These include polycyclic aromatic hydrocarbons (PAHs) and their nitro-derivatives (NPAHs) as well as microorganisms. In Africa, fossil fuel combustion and biomass burning in urban settings are the major sources of human exposure to PM, yet data on the role of aerosols in disease association in Africa remains scarce. This review is the first to examine studies conducted in Africa on both PAHs/NPAHs and airborne microorganisms associated with PM. These studies demonstrate that PM exposure in Africa exceeds World Health Organization (WHO) safety limits and carcinogenic PAHs/NPAHs and pathogenic microorganisms are the major components of PM aerosols. The health impacts of PAHs/NPAHs and airborne microbial loadings in PM are reviewed. This will be important for future epidemiological evaluations and may contribute to the development of effective management strategies to improve ambient air quality in the African continent.

Leaf morphological traits vary along climate gradients, but it is currently unclear to what extent this results from acclimation rather than adaptation. Knowing so is important for predicting the functioning of long-lived organisms, such as trees, in a rapidly changing climate. We investigated the leaf morphological warming responses of 18 tropical tree species with early (ES) abd late (LS) successional strategies, planted at three sites along an elevation gradient from 2400 m a.s.l. (15.2 °C mean temperature) to 1300 m a.s.l. (20.6 °C mean temperature) in Rwanda. Leaf size expressed as leaf area (LA) and leaf mass per area (LMA) decreased, while leaf width-to-length ratio (W/L) increased with warming, but only for one third to half of the species. While LA decreased in ES species, but mostly not in LS species, changes in LMA and leaf W/L were common in both successional groups. ES species had lower LMA and higher LA and leaf W/L compared to LS species. Values of LMA and LA of juvenile trees in this study were mostly similar to corresponding data on four mature tree species in another elevation-gradient study in Rwanda, indicating that our results are applicable also to mature forest trees. We conclude that leaf morphological responses to warming differ greatly between both successional groups and individual species, with potential consequences for species competitiveness and community composition in a warmer climate.

The native vascular flora of Rwanda is currently the subject of ongoing study aimed at producing a comprehensive and up-to-date national checklist. The discovery of Diospyros abyssinica forms part of the Flora of Akagera National Park project, a focused initiative designed to document and synthesise the vascular plant diversity of this protected area in Rwanda’s Eastern Province. The ultimate objective of this project is to generate a complete and authoritative checklist of the Park’s vascular plant species, incorporating current taxonomic treatments, verified distributional data and conservation status assessments. The checklist is being developed through the integration of systematic field observations, the assembly and analysis of a comprehensive database of herbarium specimens and a critical review of relevant published and unpublished botanical literature. A new country-level record of a native vascular plant species previously unrecorded in Rwanda emerged during 2023 fieldwork inventory in the Eastern Province. Diospyros abyssinica is reported as new to the Province, where it is represented in a relict population of only 15 individuals in less than 20 hectares. Due to the species having many uses, it has been prioritised as a species for indigenous tree planting programmes.