Assessing forest fragmentation and biodiversity impacts in sub-Saharan Africa : methodological challenges and conservation strategies for small-scale agricultural landscapes

Abstract

Tropical forests in sub-Saharan Africa (SSA) harbor around one-third of the world's species but are becoming more fragmented due to the expansion of human settlements and small-scale agricultural (SCA) areas. This study systematically reviewed the approaches and methods used to analyze forest fragmentation and its impact on biodiversity in SSA, with a focus on their suitability in SCA landscapes. The main findings revealed that most studies in SSA employed generalized approaches to assess fragmentation, failing to account for the distinct contributions of various land cover changes. The other key findings indicate that the majority of studies (i) depended on low-resolution remote sensing imagery, (ii) neglected to assess landscape metrics accuracy, and (iii) had limited focus on socioeconomic aspects. These limitations impede precise and thorough evaluation of SCA's contribution to forest fragmentation. To address these gaps, we recommend the following: (i) adoption of high-resolution images, (ii) integration of socioeconomic data, and (iii) rigorous validation of landscape metrics. Concerning biodiversity implications, 55.2% (21 out of 38) of the reviewed studies reported negative impacts, and 68.2% (26 out of 38) exhibited a taxonomic bias toward avian and tree/plant species. We recommend the following: (i) enhanced utilization of remote sensing data for biodiversity monitoring, (ii) greater emphasis on neglected taxa (e.g., small mammals and amphibians), and (iii) focused conservation initiatives for small forest fragments, which are essential for biodiversity conservation, and reducing emissions from deforestation and forest degradation in SSA.

PLAIN LANGUAGE SUMMARY The study found that small farm growing larger is the main reason animals and plants are disappearing in parts of Africa. We wanted to find ways to measure how these small farms break up forests and hurt wildlife, plants, and other living organisms. We learned that many studies have used poor-quality pictures from space and other general methods which miss important details found in small agriculture farms. Additionally, most studies on plants and animals in Africa have only focused on birds and trees. They ignore other types of creatures such as bees and frogs. Therefore, the study recommends (i) using better pictures from space and including information about people to understand how small farms affect nature, (ii) studying animals that are not often looked at, such as rats, rabbits, and frogs. Moreover, small patches of forest left between farms are important. They give birds, frogs, and rabbits a place to live and provide oxygen to breathe.