Cocoa-based agroforestry systems make a large contribution to the livelihoods of rural populations in the Centre region of Cameroon. This region corresponds to the South Cameroon plateau, whose elevation fluctuates between 650 and 900 m. Its climate is characterized by a bimodal rainfall pattern with a small rainy season from March to June and a large rainy season from August to November. The ferrallitic soils have a low organic matter content, a variable clay content (40 to 65%) and an acid pH (4.5 to 5.5). The plant composition and structure of the cocoa-based agroforestry systems vary considerable depending on the North-South climate gradient that characterizes this zone. The choice of the Bokito and Ngomedzap zones therefore takes into account the environmental diversity that characterizes the Centre region. In the forest-savannah transition zone (Bokito), the soils are less desaturated than those in the forest zone (Ngomedzap) and the rainfall is also lower there: 1,300 – 1,400 mm as opposed to 1,700-1,800 mm.

Bokito 

A peri-forest zone with a population density of 29 inhabitants/km². This zone is characterized by a mosaic of forest galleries usually located along water courses and on hill ridges, while Imperata cylindrica savannah grasslands occupy the rest of the territory. Although considered sub-optimum for cocoa, this zone has its own dynamics marked by the establishment of cocoa agroforests on savannah, thereby restoring degraded or low-fertility zones. This process prompts the long-term evaluation of these atypical systems and of the impact of their composition and structure on soil fertility.

Ngomedzap

A forest zone with a population density of 37 inhabitants/km². This zone is characterized by a vegetation dominated by dense Sterculiaceae semi-ombrophilous forests, where the influence of the Congolese forest is strongly felt. It is an old cocoa growing zone with senescent cocoa orchards and low yields, under dense forest cover with generally extensive crop management procedures. The challenge here is to identify factors that help to improve the overall productivity of these systems based on trade-offs operated by farmers. In these two zones, the main achievements are knowledge on the composition of the tree component of complex agroforestry systems, an estimation of the relative importance accorded by farmers to the different associated species, the components of cocoa tree yield and an analysis of farmers’ practices over the long term (Patrick Jagoret’s thesis), and also the two pests of cocoa tree stands, namely black pod rot (work by Martijn Ten Hoopen, theses under way for Raymond Mahob, Virginie Mfégué, Joseph Mbarga) and mirids (Régis Babin’s thesis), especially the link between stand structure and these pests and diseases (thesis under way for Yédé Pith and Cynthia Gidoin).