Diversity and ethnobotanical use-value of trees outside forests on the agricultural landscape of the Mongala Province, Democratic Republic of Congo

Trees outside forests on agricultural land (TOF-AL) are essential for the livelihoods of rural communities in the Democratic Republic of Congo, yet their diversity, use, and management are poorly documented, particularly in Mongala province. This study aimed to characterize the diversity of TOF-AL species, quantify their ethnobotanical use values, and analyze the management strategies of local communities. We conducted ethnobotanical surveys and tree inventories in 900 agricultural plots across 45 villages in the three territories of Mongala province. The data were analyzed using diversity indices, the total ethnobotanical use value (TUV_s) index, and hierarchical clustering analysis to classify species based on their use values. We identified 136 TOF-AL species on agricultural land in Mongala, with a Shannon diversity index of 3.544. The results show that more than 62% of the total abundance is concentrated in ten most common species. The clustering analysis revealed three distinct clusters of 23 privileged species: Cluster 1 (high value for energy and construction), Cluster 2 (high value for commerce and crafts), and Cluster 3 (multifunctional species with high value for food, medicine, and commerce). The high abundance of Cluster 3 species and the rarity of Cluster 2 species indicate that use value directly influences the conservation status of the species. Our results show that the diversity and abundance of TOF-AL are the result of specific management choices guided by local ethnobotanical knowledge. Species that provide continuous and non-destructive benefits are actively conserved by farmers, while those with high commercial value are threatened by intense harvesting pressure. This study calls for the adoption of differentiated management strategies to ensure the sustainability of resources. It suggests targeted reforestation programs and economic incentives for threatened species (Cluster 2) and the strengthening of existing management practices for abundant species (Clusters 1 and 3), underscoring the importance of integrating traditional knowledge into agroforestry conservation.