Long-term dynamics of cocoa agroforests: a case study in central Cameroon

Abstract

The sustainability of cocoa growing systems in the humid tropics is debatable. Socio-economic and technical data were obtained from 1,171 cocoa farmers and 1,638 cocoa plantations to assess the long-term dynamics of cocoa agroforests in central Cameroon since the beginning of the twentieth century. On-site, we estimated the age of the cocoa trees and measured their density in a sub-sample of 402 cocoa plantations. We inventoried associated woody species in 45 cocoa plantations from this sub-sample. Our results revealed a high Shannon index for the cocoa plantations (2.6) and showed that an average of 25 tree species per cocoa plantation had been planted with the cocoa trees at a density of 120 trees ha−1. Surveys indicated that there had been no mineral fertilization. Nearly 70% of the cocoa agroforests were over 40 years old, and all farmers continuously regenerated their cocoa tree stands. Irrespective of the cocoa plantation age, the cocoa tree density remained over 1,000 plants ha−1, and fermented dried cocoa yields were 255 kg ha−1 on average. Cocoa agroforests occupied 60% of the cultivated area on farms and cocoa sales accounted for 75% of total farm income. Almost a third of the farmers were from the area and under 40 years old. In conclusion, our results show that the farmers’ agroforestry practices, in addition to the fact that the cocoa tree stands were continuously regenerated and passed down between generations of farmers, could explain the long-term dynamics of cocoa agroforests in central Cameroon

Structural characteristics determine productivity in complex cocoa agroforestry systems

“…These values were in agreement with those obtained by Jagoret et al (2011) with a different experimental design, i.e., 1280 trees ha −1 (Bokito) to 1707 trees ha −1 (Ngomedzap). They were also in line with the findings of Bisseleua and Vidal (2008) who, for the same zones, recorded 1075 to 1600 cocoa trees ha −1 according to a cocoa stand intensification gradient.…”

“…This was higher than values usually obtained through surveys for cocoa agroforests in central Cameroon, i.e., 264 kg ha −1 (Duguma et al 2001), 255 kg ha −1 (Jagoret et al 2011), or elsewhere in Africa, i.e., 214 kg ha −1 in Côte d'Ivoire and 454 kg ha −1 in Ghana (Gockowski and Sonwa 2010). This would confirm the limits of surveys based on farmers' declarations.…”

“…Our study was carried out in a specific study network in central Cameroon located in three different cocoa growing zones: Bokito (4°35′ N; 11°8′ E), Zima (4°7′ N; 11°25′ E) and Ngomedzap (3°16′ N; 11°14′ E), representative of (i) the north-south gradient of natural conditions in this region (Santoir and Bopda 1995) and (ii) the local cocoa cropping systems in terms of structural characteristics (Jagoret et al 2011). Central Cameroon encompasses an area located between 2.1°to 5.8°N and 10.5°to 16.2°E, with a 600-800 m elevation range.…”

“…(ii) KkoAge (years), the mean age of cocoa trees calculated on the basis of the age of each cocoa tree indicated by the farmer. (iii) KkoNbT (n), the mean number of trunks per cocoa tree, which reflects cocoa stand rehabilitation practices under way in central Cameroon (Jagoret et al 2011). (iv) KkoBA (cm 2 ), the mean basal area per cocoa tree calculated on the basis of the diameters of each trunk per cocoa tree, measured 50 cm above the ground.…”

“…Third, assessing the specific yield of a given species in a multispecies system is hard because it involves taking explicitly into account the other cultivated species in the system, their place, and role . This is particularly the case in central Cameroon where most of the cocoa orchard is agroforestry based (Sonwa et al 2007;Jagoret et al 2011Jagoret et al , 2012 (Fig. 1) and presents a great intra-plot cocoa yield variation (Jagoret et al 2008), while factors cannot be accurately determined.…”