Cocoa (Theobroma cacao L.) is a crop that is widely cultivated across West Africa with Côte d’Ivoire, Cameroon, Ghana and Nigeria contributing about 70% of the global production. In Ghana cocoa contributes significantly to the national economy as over 20% of the world’s cocoa production comes from the country, making it the world’s second largest producer with an annual production level of over 700,000 metric tons, and an estimated cultivation area of ca. 1.6 million ha. Cocoa is mostly cultivated by smallholder farmers either as a monocrop or in association with other food crops, tree crops and under the cover of shade trees – cocoa agroforestry.

This thesis hypothesizes that canopy cover of shade trees in low input (low-to-no fertilizer application) cocoa growing systems can contribute to cocoa yield improvements. The main theme deals with shade trees diversity and its effects on cocoa production and how they can be used in the management of areas bordering protected forests. Methodologically, the thesis comprises botanical (diversity) analysis, yield assessments, various kinds of interviews and a range of methods for statistical analyses. Results show that gender of farmers influence shade tree density and diversity and that within tree species, diameter can be a simple measure of its crown cover. Cocoa yields were found to increase with increasing crown cover, contrary to the widely held belief that shade trees reduce cocoa yields. Besides, moderate fertilization increase yields. On the other hand, effects of shade trees on temperature and nutrient compositions are minimal. The thesis also shows that cocoa agroforests can be used as buffers to connect fragmented forests when farmers are given premiums on various environmental services provided by shade trees on cocoa farms. The findings have a potentially strong impact on the way cocoa is cultivated across West Africa, as they contradict the current tendency in countries like Ghana where full sun cocoa systems are increasingly applied. The thesis concludes that in low input cocoa systems, where fertilizer and pesticides are used in small quantities, shade trees can modify the environment, making cocoa trees less vulnerable to different types of stresses, thus rendering shaded systems more economically favorable compared to full sun cocoa systems.