Cocoa agroforest multifunctionality and soil fertility explained by shade tree litter traits

Manipulating plant functional diversity to improve agroecosystem multifunctionality is a central challenge of agricultural systems worldwide. In cocoa agroforestry systems (cAFS), shade trees are used to supply many services to farmers, yet their impact on soil functioning and cocoa yields is likely to vary substantially among tree species.
Here, we compared the impact of five shade tree species (Canarium schweinfurthii (Canarium), Dacryoides edulis (Safou), Milicia excelsa (Iroko), Ceiba pentandra (Kapok tree), Albizia adianthifolia (Albizia)) and unshaded conditions on the functioning of poor sandy savannah soils within eight cocoa farms in Central Cameroon. We assessed the effects of plant functional traits, leaf litterfall and fine root biomass on a range of soil functions and on cocoa yield.
Shade trees generally improved soil pH, NH4+, NO3- and Olsen P content, biomass production of bioassays, and soil total C and N content, while leaving cocoa yields unchanged. However,  ...