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

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 clearcuts and early thinnings of pine (Pinus nigra Arnold) 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 much higher revenue for logs than for wood chips from forest residues. In clearcuts, a mobile chipper was more profitable than a roadside chipper. On the other hand, the harvesting cost of logs was higher for early thinnings than for clearcuts. 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 roadside 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 with processing and intercontinental transportation 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.