Maximizing Tree Diversity in Cocoa Agroforestry: Taking advantage of Planted, Spontaneous, and Remnant Trees

Abstract

Cocoa production stands as the primary driver of biodiversity loss in West Africa. In response to this challenge, agroforestry emerges as a promising solution to restore forest cover and preserve biodiversity in agricultural landscapes. Despite distributions of millions of trees to farmers through various sustainability initiatives, survival rates of planted trees have been disappointing in cocoa fields. However, many non-planted trees currently exist in cocoa fields, including trees from spontaneous regeneration and remnants from previous forests. Our study aims to explore the origins of tree biodiversity in current Ivorian cocoa fields and identify the key socio-environmental determinants. Across 150 cocoa fields, more than 10,000 trees were botanically identified, allowing estimation of diversity and complementarity levels between planted, spontaneous, and remnant cohorts, linked to socio-environmental variables within a Bayesian modelling framework. Results revealed that remnant and spontaneous trees exhibited much greater diversity than planted trees, with the latter showing important complementarity with the other cohorts. Moreover, the diversity of each tree cohort was influenced by a distinct set of environmental factors such as climate and soil composition, highlighting the need to consider the unique history and location of each cocoa field to support agroforestry development. Effective biodiversity maximisation thus relies on preserving remnant trees, vital sources of propagules for natural regeneration, while carefully selecting spontaneous trees and complementary introducing planted trees. Furthermore, recognizing the farmer's identity as a key factor shaping observed biodiversity underscores the importance of raising awareness among farmers and offering tree recognition training, particularly for young trees.