The potential of native tree species for forest restoration in the Central Congo Basin

Abstract

Decades of deforestation and unsustainable land use have created extensive areas of degraded and deforested land across the central Congo Basin, contributing substantially to climate change and biodiversity loss. Recently, nature-based solutions have gained increasing interest, particularly those focusing on forest restoration for long-term carbon sequestration and additional societal benefits for human well-being. Thus, forest restoration, especially with native species, offers a viable pathway to address environmental and social challenges while supporting local communities. However, both technical and scientific knowledge about many native species' performance in large-scale plantations, which could serve the current and future needs of central African countries, is currently lacking. To address these knowledge gaps, we established an experimental plantation in Yangambi, Democratic Republic of the Congo, to evaluate the potential of native tree species in comparison with the fast-growing exotic species Acacia auriculiformis, which is often planted in monoculture at a large-scale in the central Congo Basin. From 37 promising native species initially selected, the seeds of 19 were successfully harvested from the natural forest. Among these, 16 species yielded sufficient seedlings in the nursery and were planted in the field. After five years, five native species (Pachyelasma tessmannii, Piptadeniastrum africanum, Irvingia smithii, Ongokea gore, and Canarium schweinfurthii) demonstrated growth, survival, and carbon sequestration performance comparable to Acacia auriculiformis. This illustrates that local tree species are promising alternatives for exotic species. Nevertheless, further research is necessary to optimize the large-scale production of native seedlings, including improving seed conservation and nursery techniques. Drawing on the ongoing forest restoration initiatives in Yangambi, we emphasize the importance of integrating local knowledge and actively involving local communities to ensure the successful implementation and long-term sustainability of tree-planting efforts, benefiting both nature and human well-being.