Leaf functional traits and farmer knowledge predict decomposition of shade-tree leaves in Colombian cacao agroforestry

van der Vrande M.; Fremout T.; Lohbeck M.; Campos-Melendez A.; Pulleman M.; Thomas E. · Agroforestry Systems (2026) · DOI: 10.1007/s10457-026-01642-0

Resumen

Poor soil fertility is a major cause of low productivity in smallholder cacao (Theobroma cacao L.) plantations. In cacao agroforestry, both cacao trees and associated shade trees can influence soil fertility via the decomposition of leaf litter or pruning residues. These organic inputs can increase soil organic matter content and nutrient availability, yet their contribution varies widely among tree species. This highlights the importance of selecting appropriate shade tree species, which can be informed by farmers’ knowledge. We measured leaf decomposition rates of shade trees commonly used in cacao agroforestry in Colombia to examine whether species functional traits can predict these rates and evaluated how these findings align with farmers’ perceptions. A common garden experiment was established to assess leaf decomposition of 15 shade tree species and cacao, with leaves collected from 46 cacao agroforestry systems across the country. For each species, we measured or compiled data on 12 functional traits, including leaf nitrogen-, phosphorus-, potassium-, carbon-, calcium-, and chlorophyll content, specific leaf area, and carbon-to-nitrogen ratio, along with maximum height, wood density, deciduousness, and nitrogen-fixing ability. Farmers were asked to free-list shade tree species based on their perceived leaf decomposition rate and contribution to soil fertility. Our results show that leaf nutrient contents predict leaf decomposition rates and that farmers’ knowledge closely reflects these experimental results. This study emphasizes the role of fast-growing, resource-acquisitive species in enhancing nutrient cycling and highlights the value of farmers’ ecological knowledge in guiding shade tree selection in cacao agroforestry. © The Author(s), under exclusive licence to Springer Nature B.V. 2026.