Performance of two shear heads for harvesting biomass in hardwood stands in France

Abstract

The increasing demand for energy wood in Europe is accompanied by the development of new harvesting tools to mobilize forest biomass, notably hardwood biomass. Two logging operations are targeted more specifically: the first thinnings in regular high forest, and the clear cuttings of traditional coppices and of high productive short rotation coppices. The challenge is to find efficient and sustainable harvesting tools for hardwood trees that are very common in central and southern Europe.Two French manufacturers have recently developed shear heads dedicated to hardwood: Jacquier C360 and Sève S350. Nowadays, many logging companies are investing in these tools, as they are relevant to the whole tree system that has been adopted for harvesting woody biomass.The performance of these shear heads was determined on 3 logging sites in the North East of France. A regression analysis was run in order to evaluate models for cutting productivity of each machine, considering significant factors influencing productivity: tree size and stand type (high forest/coppice).The two shear heads were more productive at high forest than at coppice. The stand type had a significant effect only on the C360’s productivity. At high forest sites with small diameter trees, the C360 was 11.8% more productive than the S350. However, at coppice site, the S350 was 15% more productive than the C360 for harvesting big clumps. Results showed that working in coppice forest requires a head that must be very powerful and have a wide opening.