Improving the Sustainability of Pollarding in Multifunctional Agro-Forestry Plantations

Pollarding is an ancient agroforestry practice that greatly contributes to the sustainability of farming but is slowly becoming extinct because traditional pollards are not viable from a financial and social viewpoint. In particular, the cutting of pollards is too slow, expensive and dangerous for modern farmers to apply. This study presents the first test of mechanized pollarding, performed with two different devices: a set of shears and a disc saw. Both devices were fitted to the boom tip of a tracked excavator and were tested on poplar rows in a typical alley-cropping system. The introduction of those simple devices restored productivity and safety to pollarding as a modern practice. Tree topping incurred a cost around 1 € tree−1, or 250–350 € ha−1. This cost would need to be balanced against the revenue obtained from the treetops sold as biomass and the increased yields of the alley crop, prolonged for several years. Mechanization also allows cutting the treetops several metres above ground level, so that the trunks of the pollarded trees may yield valuable timber when they are eventually harvested.