Aboveground Biomass and Carbon content of a cocoa –Gliricida sepium agroforestry system in Ghana

S Owusu,S Abugre,L C N Anglaaere

doi:10.4314/gjas.v53i1.4

Abstract

To help overcome the challenge faced in re-establishing cocoa in degraded lands, some agroforestry trials were established with exotic leguminous tree species to determine their suitability for cocoa cultivation. However, our understanding of biomass accumulation and carbon sequestration in such specific agroforestry practices is still limited. In this study, the above-ground biomass and carbon storage and partitioning in a gliricidia-cocoa agroforestry system was investigated. Above-ground biomass accumulation and carbon stock varied significantly between the components of the system, with the gliricidia shade trees having the highest values and the cocoa trees having the lowest. The inclusion of the gliricidia shade trees in the system increased above-ground biomass and carbon capture of the system by some 60%, a greater proportion of which was contained in the branches of the shade trees. This pattern of dry matter distribution makes the species appropriate for use as a biomass producing species in agroforestry systems and demonstrates the potential of cocoa agroforestry systems for capturing and storing more atmospheric carbon than sole cocoa systems.

Highlights

Cocoa (Theobroma cacao L.) agroforests are a common farming system in the humid zone of West and Central Africa, in which forest trees provide shade and other environmental services as well as marketable products (Oke & Odebiyi, 2007)
It consists of cocoa planted at a regular spacing of 3m x 3m, with Gliricidia sepium as the shade tree planted at a spacing of 6 m x 6 m
This may be due to the higher stocking densities of both cocoa and G. sepium in the later study, which would have resulted in competition between the trees for light resulting increased height growth compared to our stand

Summary

Introduction

Cocoa (Theobroma cacao L.) agroforests are a common farming system in the humid zone of West and Central Africa, in which forest trees provide shade and other environmental services as well as marketable products (Oke & Odebiyi, 2007). Small holder cocoa farmers establish their farms by removing the forest under-storey and thinning the forest canopy so that cocoa seedlings can grow into productive trees (Duguma et al, 2001). In Ghana, for instance, it is estimated that 80 % of the forest area has disappeared since cocoa trees were introduced (Cleaver, 1992). Re-establishing cocoa in these areas has proven difficult due to low soil fertility, bush fires, diseases and pest, and inappropriate vegetation cover to provide shade for young cocoa (Adams, 1962; Ayanjala, 1983).

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Results

Discussion

Conclusion