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Traditional cacao agroforestry in Central Africa can provide both respectable yields and levels of ecosystem services

Saj S., Jagoret P.. 2017. In : Proceedings of the International Symposium on Cocoa Research 2017. Lima : ICCO, 8 p.. International Symposium on Cocoa Research (ISCR 2017), 2017-11-13/2017-11-17, Lima (Pérou).

Since it moved toward-and tried to apply-intensive production patterns, cacao cultivation in Sub-Saharan Africa represents a major driver of deforestation. In Cameroon, most cacao is still cultivated in low-input traditional agroforests (C AFS). Such systems are still criticised for their presumed low cocoa production and seemingly economic and ecological inefficiency of their associated tree community (ATC). Yet, these household systems proved to be sustainable on the long run and marginally threaten forest land when compared to other producing regions or agricultural systems. We studied a cAFS' 100-year chronosequence and checked for three ecosystem services they provide: (i) cacao production; (ii) carbon (C) storage in tree biomass and (iii) tree species conservation. Within this chronosequence we also studied a large array of associated trees densities (ATD) to better appreciate the role of competition on the services studied. We used, among other variables, basal area (BA) of the different components of the systems to gauge interspecific competition, functional group dynamics and cacao trees productive abilities. Yields were highly depending on the age of the plot, the BA of the ATC and the structure of the cacao stand. Very long-term production seemed achievable if the BA of the cacao stand remained under 40% of CAFS' total BA. High accessible yields underlined a good production potential which was mitigated by interspecific competition. Yet, for a given level of competition some associated functional groups of the ATC were consistently related to higher cacao yields. Furthermore, CAFS were able to combine high levels of tree species richness with long-term conservation abilities and C storage. However, tree species conservation potential depended on ATD and remained difficult to appraise. C storage was highly dependent on large trees and not systematically mitigated by ATD - underlining the possible ¿uncoupling¿ of tree species conservation and C sequestration in those systems. ATD reduction emphasised consistent shifts of functional traits / groups that are to alter CAFS functioning and ATC diversity of uses. Thus, a ¿rough simplification¿ - as regularly advocated to alleviate the competition between cacao stands and ATC ¿ is mos t likely to impair traditional CAFS ecosystem sustainability. We argue that cacao productivity in these systems can be raised combining consistent rejuvenation and densification practices with site-specific intensification in terms of inputs and/or manpower. Such intensification would not compulsorily include ATD reduction and therefore would, at least partly, facilitate the preservation of some of the ecosystem services supported.

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