Logging operations in pine stands in Belgium with additional harvest of woody biomass: yield, economics and energy balance.

Abstract

Due to the enhanced demands for woody biomass, it is increasingly relevant to assess possibilities to harvest forest residues in addition to logs. Here, eight strategies for whole tree harvesting from clear-cuts and early thinnings of pine (Pinus nigra) stands in northern Belgium are evaluated. A detailed cost analysis using the machine rate method was conducted along with scenario and sensitivity analyses of the variables affecting the harvesting cost. On average, we found a much higher revenue for logs than for wood chips from forest residues. In clear-cuts, a mobile chipper was more profitable than a road-side chipper. In early thinnings, on the other hand, the harvesting cost of logs was higher than for clear-cuts. However, the revenue remained higher than for chips, making the separate harvesting of logs and chips more cost-effective than chipping whole trees. In the latter case, an excavator, a forwarder and a road-side chipper were more cost-effective than a harvester, a tractor with trailer and a mobile chipper, respectively. Harvest of additional woody biomass required limited energy input compared to processing and intercontinental transport of wood pellets. However, at present we find very small profits from local additional biomass harvests. The low and fragmented forest cover and important sustainability issues further impede the development of a viable production sector in this region.