Urban and peri-urban expansion significantly influences the spatial pattern of cities and surrounding zones. This study examines the spatial changes in green infrastructure components, specifically focusing on mature forests, short forests, and agricultural and grass lands from 1986 to 2021, using satellite imagery. Two landscape ecology indexes, the percentage of landscape (PLAND), and the largest patch index (LPI), were applied. PLAND provides insights into the proportion of habitat types, capturing overall extent, while LPI elucidates their spatial configuration. The research is conducted in a specific context of increasing urbanization and peri-urbanization in Kisangani city, DR Congo. The findings reveal a decline in both mature and short forests, respectively, from 1986 to 2021, and from 2006 to 2021 alongside a continuous expansion of agricultural and grass lands at the landscape scale. Moreover, the spatial pattern of mature and short forests exhibited significant variations across urban, peri-urban, and rural zones. In the context of 2021, in urban and peri-urban zones, mature forests account for less than 1% of the 2.25 km² plots, against more than 35% in certain rural plots. Similarly, larger patches of mature forest in urban and peri-urban zones cover less than 0.5% of the 2.25 km² plots, whereas they exceed 20% in rural zones. From 1986 to 2021, both mature and short forests experienced significant decline and fragmentation, particularly in urban and peri-urban zones, while agricultural and grass lands increased significantly in peri-urban and rural zones. These results raise concerns regarding the functions, services, and opportunities provided by mature and short forests in the context of global change. They also highlight the need for urban planning in Kisangani to prioritize green infrastructure preservation, focusing on maintaining forest connectivity and preventing further fragmentation. Policies should promote sustainable land use in peri-urban zones to achieve a balance between urban expansion and the provision of essential ecosystem services, thereby enhancing long-term resilience.

Biodiversity conservation is a key factor in meeting sustainable development goals. This is even more important in cities, where green spaces are becoming increasingly scarce. This study analyzes Kinshasa’s proliferating ornamental plant nurseries, known as informal horticultural sites (IHSs). The analysis focused on characterizing the profile of horticulturists, their production conditions, and the ornamental species produced. A total of 15 IHSs were sampled using the “snowball” technique, and 178 horticulturists were surveyed. Based on the socio-professional profile of the horticulturists, five groups of IHS are distinguished after a hierarchical clustering of principal components (HCPC). We found that IHSs exclusively employed men, most of whom were new to the trade, from all levels of education, and most of whom ranged from 19 to 45 years old. Production conditions are relatively similar from one site to another. However, all IHSs are characterized by permanent land insecurity, the use of phytosanitary products, plant-conditioning methods that are not very diversified and calibrated to growers’ investment capacities, and diversified seed acquisition methods. A total of 139 ornamental species, most of them exotic, were identified. Of these, 37% are phanerophytes, and 24% are considered potentially invasive. We suggest ways of professionalizing the activity and protecting the urban environment.

This study analyses the dynamics of green infrastructure (GI) in the cities of Bujumbura, Kinshasa, and Lubumbashi. A remote sensing approach, combined with landscape ecology metrics, characterized this analysis, which was based on three Landsat images acquired in 2000, 2013, and 2022 for each city. Spatial pattern indices reveal that GI was suppressed in Bujumbura and Kinshasa, in contrast to Lubumbashi, which exhibited fragmentation. Furthermore, the values of stability, aggregation, and fractal dimension metrics suggest that Bujumbura experienced rather intense dynamics and a reduction in the continuity of its GI, while Kinshasa showed weaker dynamics and tendencies towards patch aggregation during the study period. In contrast, Lubumbashi exhibited strong dynamics and aggregation of its GI within a context of significant anthropization. The evolution of the Normalized Difference Vegetation Index demonstrates a sawtooth pattern in the evolution of tall vegetation patches in Bujumbura, compared to a gradual decrease in Kinshasa and Lubumbashi. It is recommended that urban growth in these cities should be carefully planned to ensure the integration of sufficient GI.

This study maps and quantifies the green infrastructure of the cities of Bujumbura, Kinshasa and Lubumbashi. A remote sensing approach, in conjunction with landscape ecology metrics, characterized this analysis, which was based upon three Landsat images acquired in 2000, 2013 and 2022 for each city. Spatial pattern indices show that green infrastructure was suppressed in the cities of Bujumbura and Kinshasa, in contrast to the city of Lubumbashi, which was characterized by a fragmentation of its green areas. Additionally, the values of the stability, aggregation and fractal dimension metrics suggest that the city of Bujumbura underwent rather intense dynamics and a reduction in the continuity of its green areas, while the city of Kinshasa shows weaker dynamics and tendances of patch aggregation in the study period. The city of Lubumbashi, in its turn, exhibits strong dynamics and an aggregation of its green infrastructure, in a context of a high level of anthropization. The evolution of the Normalized Difference Vegetation Index shows a sawtooth evolution of tall vegetation patches for the city of Bujumbura, against a gradual decrease in Kinshasa and Lubumbashi. It is advocated that the urban growth of these cities should be planned carefully in order to integrate the presence of sufficient green infrastructure.

Urbanization’s environmental challenges have increased interest in urban biodiversity, traditionally focused on public green spaces, which are shrinking as urban growth escapes government control. This study examines the understudied role of private actors—specifically Concessions held by Catholic Religious Groups (CRGs)—in biodiversity conservation across three DRC cities (Bukavu, Kisangani, Lubumbashi). CRGs were selected due to Catholicism’s dominance and socio-economic influence in the DRC. A systematic flora inventory of 70 randomly sampled CRGs identified 220 species from 76 families and 185 genera. Although the CRG area was smaller in Lubumbashi (1.1 ha) than Bukavu (3.7 ha) and Kisangani (5.2 ha), the area did not correlate with species richness. Plant composition varied significantly within and between cities, dominated by phanerophytes and exotic species. These findings underscore the importance of including private stakeholders in urban biodiversity conservation.

Biodiversity conservation is a key factor in meeting sustainable development goals. This is even more important in cities, where green spaces are becoming increasingly scarce. This study analyzes the Kinshasa's proliferating ornamental plant nurseries, known as informal horticultural sites (IHS). The analysis focused on characterizing the profile of horticulturists, their production conditions and the ornamental species produced. Fifteen IHSs were sampled using the "snowball" technique, and 178 horticulturists were surveyed. Based on the socio-professional profile of the horticulturists, five groups of IHS are distinguished after a hierarchical classification on principal components. We found that IHSs exclusively employed men, most of whom were new to the trade, from all levels of education, and most of whom ranged from 19 to 45 years old. Production conditions are relatively similar from one site to another. However, all IHS are characterized by permanent land insecurity, the use of phytosanitary products, plant conditioning methods that are not very diversified and calibrated to growers' investment capacities, and diversified seed acquisition methods. A total of 139 ornamental species, most of them exotic, were identified. Of these, 37% are phanerophytes and 24% are considered potentially invasive. We suggest ways of professionalizing the activity and protecting the urban environment.