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In Africa's main cocoa producing countries, rehabilitation of old cocoa orchards is increasingly debated but rarely adopted. In Central Cameroon, rehabilitation practices are regularly set up in old cocoa-based agroforestry systems (cAFS). To better understand the impact of such practices we built a chronosequence of 40 cAFS. We carried out specific surveys with farmers on each plot in order to check for rehabilitation effects on cocoa stands and associated woody species (AWS). We found that cocoa trees represented on average 88.2% of woody individuals and increased with age (from 84.7 to 91.5%). The cocoa stand basal area (BA) share significantly increased with age and reached up to 40.2% in the oldest systems. Cocoa, fruit and forest trees mean BA increased with aging. They were on average of 6.5, 5.7 and 10.7 m2 ha−1 respectively. Six different architectural types, different from the theoretical architectural evolution of cocoa trees over time, were identified. Among them, type 4 characterized by several orthotropic suckers of differing ages, was found typical of farmers' cutting back practices. Type 4 cocoa trees density increased over time and its BA represented on average 60% of cocoa stand BA in the oldest systems. Concomitantly, farmer's management of AWS led to continuous evolution of the systems both in terms of density and species composition. Our results show that (i) permanent densification and cutting back practices (type 4) allow the rejuvenation of cocoa stands while increasing cocoa stands BA share; (ii) the continuous management of AWS by farmers is undertaken to favour cocoa trees share over time by limiting inter-specific competition and promoting complementarity between cocoa trees and AWS. We argue that such practices explain a fair part of the long-term sustainability observed in cAFS from Central Cameroon and represent a model from which new rehabilitation schemes could be inspired. (Résumé d'auteur

In order to cope with current challenges facing world cocoa production and the obvious lack of sustainability of the intensive model proposed to farmers, more ecologically efficient cocoa cropping systems must be developed, based in particular on a higher cultivated biodiversity level. The performances of cocoa multispecies systems, which involve multiple and hard to quantify interactions, are, however, more complicated to assess than that of monospecies systems. Despite this hurdle, we carried out a study in 48 cocoa agroforests located in three zones in central Cameroon where we conducted an analysis of cocoa yield components and agroforestry system structural characteristics that are likely responsible for observed yield variations. For the first time, we adapted the regional agronomic diagnosis method to demonstrate that the basal area per cocoa tree (mean 61.6 cm 2 ) and the unproductive adult cocoa tree rate (mean 21%) are key factors when assessing the productive performance of the surveyed systems whose average cocoa yield was 737 kg ha −1. From a methodological standpoint, the assessment approach we set up succeeded to overcome the specific obstacles linked with the features of agroforestry systems, especially their complexity (number of species and heterogeneity), by (i) determining relevant indicators and easily measurable variables, (ii) considering the associated tree communities as an environmental component, and (iii) analyzing interactions between cocoa stands and associated tree communities. From an operational standpoint, we showed that farmers can intervene on the structural characteristics of their cocoa agroforests to improve cocoa yields, in particular by eliminating unproductive cocoa trees whose basal area is less than 19 cm 2 to enable the other ones to grow.

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