Mechanized Pollarding For The New Agroforestry Plantations

Pollarding is an ancient agroforestry practice that offers many benefits but is slowly becoming extinct because traditional pollards lack financial and social sustainability. 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 machines 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 machines restored productivity and safety to pollarding as a modern practice. Tree topping incurred a cost around 1 € tree-1, or 250-350 € ha-1. That 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 meters above ground level, so that the trunks of the pollarded trees may yield valuable timber when they are eventually harvested. Both machines on test performed well, but the disc-saw seemed preferable, especially if installed on a compact excavator.