The tree species diversity – Soil macrofauna nexus in cocoa-based agroforests in Cameroon: A biophysical assessment

Cocoa-based agroforests are vital for biodiversity conservation, supporting diverse tree species and soil macrofauna, which play key roles in ecosystem functioning and productivity. Limited understanding of how tree species diversity influences soil macrofauna hampers the optimization of agroforestry practices for sustainable cocoa production and biodiversity preservation. This study investigates the nexus between tree species diversity and soil macro-fauna in cocoa-based agroforests in the littoral region of Cameroon. The methodology used included standardized quadrat sampling (40 × 40 m²) across 50 farms for tree species and 100 quadrats (20 × 20 m²) for soil macro-fauna. Diversity indices and relative abundance metrics quantified species richness and ecological importance. Findings reveal that cocoa-based agroforests harbor significant tree and macro-faunal diversity, contributing to ecosystem services such as nutrient cycling and pest regulation. The dominance of functional species, like nitrogen-fixing Albizia spp. and decomposer earthworms, underscores their ecological value. Tree inventories conducted on cocoa farms identified 33 tree species, with Theobroma cacao , Cola acuminata , Persea americana , Musa spp. , and Dacryodes edulis exhibiting the highest frequencies and densities. The Shannon-Wiener Diversity Index for tree species was 2.321, highlighting substantial diversity. Soil macro-fauna surveys revealed 13 functional groups, including termites, ants, earthworms, millipedes, and spiders. Notable species, such as Lumbricus terrestris (earthworm) and Coptotermes formosanus (termite), displayed high frequency and density. In conclusion, cocoa agroforests in Cameroon represent biodiversity hotspots essential for sustainable agroecosystem management. Enhancing tree and soil fauna diversity through farmer education and agroforestry practices is recommended to ensure long-term productivity and resilience.