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.

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.

In Haiti, uncontrolled urbanization is increasing pressure on agricultural landscapes, compromising both their ecological integrity and productivity. This study examines spatio-temporal land-use changes across three agricultural plains, Cul-de-Sac, Maribahoux, and Léogâne, between 1997 and 2024, using Landsat imagery and landscape metrics of composition (percentage of landscape, PLAND) and configuration (largest patch index, LPI). The findings reveal a rapid expansion of built-up areas, primarily at the expense of farmland. In the Cul-de-Sac plain, built-up areas and bare soil grew by 152%, from 41.26 km² to 104.11 km², while agricultural land became highly fragmented (LPI dropping from 94.51% to 57.63%). In Maribahoux, urbanization was more moderate, partly offset by a temporary rise in woody vegetation that peaked at 20.04% in 2022 before declining. The Léogâne plain experienced a 17.38 km² increase in built-up areas and bare soil, alongside a slight decrease in woody vegetation. Population density showed limited differences in Maribahoux and Léogâne, but marked disparities in Cul-de-Sac, where landscape transformation was more pronounced. These findings highlight increasing fragmentation of agricultural landscapes, threatening ecological connectivity and functionality, and stress the urgent need for land-use planning that curbs urban growth, protects farmland, and safeguards biodiversity.

Montane forests of Kahuzi-Biega National Park (PNKB), located in the Albertine Rift, represent a major reservoir of biodiversity and carbon, yet they are increasingly affected by anthropogenic disturbances despite their protected status. This study aimed to assess whether these disturbances are spatially heterogeneous and organized into non-random regimes; whether they simplify forest structure, reduce aboveground biomass, and alter floristic diversity; and whether they influence community composition both indirectly through forest structure and directly as ecological filters. Nine transects, each 1 km in length and comprising seven 0.25 ha plots spaced approximately 100 m apart, were established in the high-altitude zone. Each transect represented a disturbance gradient ranging from more accessible areas to more remote locations. Disturbances were characterized using field-based indicators and analyzed through similarity indices and hierarchical clustering, while their effects were assessed using non-parametric tests and multivariate analyses (NMDS, PERMANOVA, dbRDA). Similarity analyses revealed a non-random organization of disturbances, dominated by the co-occurrence of logging, charcoal production, and agriculture. Disturbed plots exhibited significant reductions in tree density (−42%), basal area (−54%), and aboveground biomass (−51%; 53 vs 109 Mg ha⁻¹, p < 0.001). Species richness was lower (p = 0.047), and floristic composition differed significantly among disturbance categories (PERMANOVA, p < 0.01). Disturbances independently explained 10% of the variation in floristic composition, while the full model accounted for 31%, indicating both structural and directional effects on plant assemblages. These findings demonstrate that diffuse but cumulative disturbances can act as major structuring forces, capable of durably reshaping the ecological trajectory of tropical montane forests, even within protected areas.