A new study based on detailed field measurements in West Africa shows cocoa agroforestry to be less drought resilient than previously thought. The strong El Niño event of 2015/2016 bringing hot winds with temperatures up to 44 ˚C and severe water limitations wiped out cocoa in agro-forestry systems.
The findings call for a rethinking of the climate adaptation options in the most important cocoa production region of the world.
The study was conducted by doctoral student Issaka Abdulai of the Tropical Plant Production and Agricultural Systems Modelling (TROPAGS) division of the University of Göttingen. It was published in the scientific journal Global Change Biology.
Over 70 percent of the world cocoa supply comes from West Africa, a region known to be vulnerable to climatic change and experiencing more frequent agroclimatic extremes in recent years.
El Niño events affect the region and have occasionally resulted in severe and long-lasting droughts with considerable yield penal-ties for cocoa, which is very sensitive to water deficits.
In West Africa and elsewhere, cocoa-agroforestry systems often have been promoted as a silver bullet for sustainable farming, generally but also in view of their modification of the micro-climate as an adaptation strategy to prevailing climate risks.
Abdulai assessed the resilience of cocoa plants under agroforestry and full sun systems to drought.
He conducted experiments using sophisticated sapflow, micro-climate and soil water measurement techniques.
“The study demonstrated that in extreme drought situations, cocoa under full sun appears to be more climate-resilient than systems with shade trees”, says Abdulai. Soil water competition under agroforestry was identified to override the benefits of micro climate moderation by shade trees during the extreme drought periods. The agroforestry systems recorded complete cocoa plant mortality while those under full sun survived and recovered.
“Under extreme climate with severe drought conditions, the role of the widely grown shade trees on cocoa plants became critical as competition for soil water with cocoa plants had been intensified”, explains Prof. Dr. Reimund P. Rötter, Head of TROPAGS division and supervisor of Abdulai.
“The importance of these results is underlined since other researchers reported that climate change is projected to cause over 50 percent of the current cocoa production areas in West Africa to face marginal climate conditions by 2050”, says Dr. Munir Hoffmann, a Postdoc of TROPAGS division.
Rötter adds: “These findings will have considerable policy implications and demand for a rethinking of the climate adaptation options in the most important cocoa production region of the world.”
The study was conducted within within the project “Trade-offs and synergies in climate change adaptation and mitigation in coffee and cocoa sys-tems in Ghana and Uganda”, which was funded by the German Federal Ministry for Economic Cooperation and Development.
Original publication: Abdulai, I. et al. Cocoa agroforestry is less resilient to sub-optimal and extreme climate than cocoa in full sun. Global Change Biology. Doi:10.1111/gcb.13885.
