Modelling agroforestry systems

Agroforestry can be defined as ‘the practice of deliberately integrating woody vegetation (trees or shrubs) with crop and/or animal systems to benefit from the resulting ecological and economic interactions’ (Burgess and Rosati, 2018). In the Oxford English Dictionary a ‘system’ is defined as ‘a set of things working together as a mechanism or interconnecting network’. Hence, for the purpose of this chapter we assume that an agroforestry system is an interconnecting network of woody vegetation with crops and/or animals that work together. There are large temporal differences in the growth and development of the woody component in an agroforestry system and the crop and/or animal component. The time frame between planting a tree and it reaching maturity can be 20–100 years whereas an annual crop and some animals can reach maturity in months. Hence the growth periods for the trees and the crops and livestock in agroforestry systems are substantially different. This diversity in the range of time, and also spatial, scales and the typically non-linear ways in which the components interact mean that agroforestry is a ‘complex’ system (Boulton et al., 2015).