Multifunctional agroforestry parklands support tree diversity, carbon stocks, and threatened native species conservation across landscape gradients in semi-arid West Africa

Agroforestry is a sustainable agricultural land-use practice that can reduce greenhouse gas emissions and mitigate climate change by sequestering carbon, among other ecosystem services. However, there is a lack of scientific data on some aspects of its multifunctionality in semi-arid West African production landscapes, especially in Ghana. Hence, this study examined the impact of agroforestry parklands on tree diversity, conservation, carbon stock, and ecological importance value across a landscape gradient in the northern savanna of Ghana. We hypothesised that these metrics would increase near (village periphery) and at intermediate (<5 km) distances from villages, compared to farther distances (5–10 km). Tree inventory data using the point-centred quarter technique were subjected to multiple analyses, including rarefaction, linear regression, and non-metric multidimensional scaling, to address our hypothesis. Our findings revealed that farms located near and at intermediate distances tend to have higher expected tree species richness (based on rarefaction) and a greater number of ecologically important species than those farther away. We argue that farmers' decisions to retain more native tree species of high economic value on their farms, rather than exotic or introduced species near villages, may be a response strategy to declines in the availability of tree products in the surrounding landscape. This strategy directly supported the conservation of globally threatened native species, which comprised 17% of the total landscape composition (e.g., Pterocarpus erinaceus Poir. and Khaya senegalensis (Desr.) A. Juss), while globally threatened exotic species constituted a small fraction of the 21% of the total threatened species identified. The estimates of carbon stocks in the study area indicate the potential of agroforestry to sequester carbon in production landscapes. Our findings underscore the importance of agroforestry parklands in enhancing carbon stocks and supporting conservation efforts by promoting the retention of trees on farms for sustainable use, particularly when economically threatened native species are involved.