A sensitivity analysis based on numerical simulation is presented, in order to investigate the anchorage resistance of root systems. The form and mechanical characteristics of roots used in the models were derived from experimental results found by previous authors. Finite element models were developed to analyse the mechanical process of uprooting. The analysis of local phenomena occurring during uprooting was performed using 2D models, whereas the anchorage of complete tree root systems used 3D models. The principal parameters which determined root shape and material properties were varied so that their influence could be evaluated. The design of experiments method (DOE) was used to generate an optimal number of root / soil configurations. It was possible to determine the influence of each of these parameters, therefore the modelling carried out provided a broad overview of the interacting mechanisms taking place during uprooting.