Pruning affects tree functioning by removing biomass and triggering compensatory responses. Functional-structural plant (FSP) models, combining three-dimensional plant architecture with physiological processes, are suitable tools to study pruning effects. We present and evaluate the first FSP model for cocoa trees and we simulate pruning impact on young cocoa tree functioning. We performed two experiments: a parametrization experiment, assessing branching responses to pruning treatments (heading and thinning); and an evaluation experiment measuring the pruning effects on stem radius, leaf number and crown diameter of cocoa trees.

We developed a FSP model that simulates tree growth as a result of the interaction between physiological processes, tree architecture and pruning-induced changes in branching patterns. Bud break is simulated stochastically, based on bud position and pruning interventions, and was parameterized with field observations. The evaluation experiment was replicated in silico to evaluate model predictions and quantify the effect of pruning on tree functioning.

Our model captured the immediate effects of pruning on tree structure and partially simulated the compensatory response in leaf production observed in the experiment. In the simulations, pruning reduced total light interception. The simulated mean light interception per unit leaf area was increased only by the thinning treatment. However, this advantage was quickly lost due to induced branch production.

Our model is a novel tool to study the short-term impact of pruning, as it explicitly simulates tree architecture and pruning-induced responses. Results highlight the necessity of dynamic simulations to understand the long-term impact of pruning in cocoa, even though long-term evaluation data is still necessary.

Detailed description of the material and methods to produced the data described here can be found in the Material and Methods sections of Tosto et al 2025. Addition information on experimental and model design can be found in supplementary material Methods S1 Methods S2.