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International audienceGiven the complexity of intercropping systems, models can be especially helpful to analyse them comprehensively. The present work puts forward a modelling approach based on an extension of sole crop models, considering the system to be composed of two species instead of one. The chosen sole crop model is STICS and its adaptation to intercropping relies first on a simplified definition of the complex agronomic system, which is subdivided into three sub-systems: the dominant canopy, and the shaded and sunlit parts of the understorey canopy. It is assumed that no inversion of dominancy occurs during the cycle of the shorter duration crop. Each of the sub-systems is embedded in a different light microclimate, estimated from a radiative balance module, assuming that a simple geometric shape can represent the dominant canopy. This radiative balance pilots the differential behaviours of the sub-systems in terms of growth, LAI dynamics, water and nitrogen uptakes and stress indices. The estimation of the water requirements for both crops relies on light partitioning coupled to a resistive scheme and applied at a daily time-step. In the soil, the horizontal differentiation is neglected in favour of the vertical one. As far as below-ground competition for water and nitrogen is concerned, it is assumed that the interactions between the two root systems result from the influence of the soil on each crop root profile through its water content dynamics. Data sets from three different intercrops, two annual and one perennial systems grown in French Antilles, were used for parameterisation of the model and verification of its consistency. The intercrop-specific modules of the model are described and discussed in comparison with the other existing models

Agroforestry, the intentional integration of trees with crops and/or livestock, can lead to multiple economic and ecological benefits compared to trees and crops/livestock grown separately. Field experimentation has been the primary approach to understanding the tree–crop interactions inherent in agroforestry. However, the number of field experiments has been limited by slow tree maturation and difficulty in obtaining consistent funding. Models have the potential to overcome these hurdles and rapidly advance understanding of agroforestry systems. Hi-sAFe is a mechanistic, biophysical model designed to explore the interactions within agroforestry systems that mix trees with crops. The model couples the pre-existing STICS crop model to a new tree model that includes several plasticity mechanisms responsive to tree–tree and tree–crop competition for light, water, and nitrogen. Monoculture crop and tree systems can also be simulated, enabling calculation of the land equivalent ratio. The model’s 3D and spatially explicit form is key for accurately representing many competition and facilitation processes. Hi-sAFe is a novel tool for exploring agroforestry designs (e.g., tree spacing, crop type, tree row orientation), management strategies (e.g., thinning, branch pruning, root pruning, fertilization, irrigation), and responses to environmental variation (e.g., latitude, climate change, soil depth, soil structure and fertility, fluctuating water table). By improving our understanding of the complex interactions within agroforestry systems, Hi-sAFe can ultimately facilitate adoption of agroforestry as a sustainable land-use practice.

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