Harvesting techniques for non-industrial biomass plantations

Two harvesting systems especially designed for non-industrial short-rotation forestry (SRF) plantations on farmland were evaluated. Both systems were based on versatile forest technology commonly used for conventional logging operations. They differed especially in where chipping was performed: in the field (terrain chipping) or at the field's edge (roadside chipping). Both systems were tested on two of the most common SRF poplar clones in Italy, namely: AF2 and Monviso. Results were encouraging: harvesting cost varied from 16.3 to 23.2 EUR t-1, and was lower for terrain chipping and for the most productive clone (Monviso). Energy consumption varied between 147 and 212 MJ oven-dry tonne-1, following the same trends as for harvesting cost. Resulting energy output-input ratios varied from 94 to 139. Life cycle impact assessment showed that the global warming potential (100 yr) was in the range of 2.4-3.4 kg CO2 eq. oven-dry tonne-1. Despite its higher cost, roadside chipping was preferred for its better terrain capability and for the superior storage quality of uncomminuted biomass. Both systems were suboptimal in their current configurations. They could offer a better performance with minor improvements.