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Abstract: For woody biomass to make a significant contribution to the United States' energy portfolio, harvesting contractors must economically harvest and transport energywood to conversion/processing facilities. We conducted a designed operational study in the Coastal Plain of North Carolina, USA with three replications of three treatments to measure harvesting productivity and costs when utilizing woody biomass. The treatments were: a conventional roundwood only harvest (control), an integrated harvest in which merchantable roundwood was delivered to mills and residuals were chipped for energy, and a chip harvest in which all stems were chipped for energy use. The harvesting contractor in this study typically delivers 2200–2700 t of green roundwood per week and is capable of wet-site harvesting. Results indicate that onboard truck green roundwood costs increased from 9.35 $ t−1 in the conventional treatment to 10.98 $ t−1 in the integrated treatment as a result of reduced felling and skidding productivity. Green energy chips were produced for 19.19 $ t−1 onboard truck in the integrated treatment and 17.93 $ t−1 in the chip treatment. Low skidding productivity contributed to high chip costs in the integrated treatment. Residual green biomass was reduced from 18 t ha−1 in the conventional treatment to 4 and 3 t ha−1 in the integrated and chip treatments, respectively. This study suggests that until energywood prices appreciate substantially, loggers are unlikely to sacrifice roundwood production to increase energywood production. This research provides unique information from a designed experiment documenting how producing energywood affects each function of a harvesting system. [Copyright &y& Elsevier]

Abstract: Loblolly pine plantations are the most important source of forest products in the US and the slash remaining after conventional harvest represents a significant potential source of bioenergy. However, slash removal in intensive harvests might, under some circumstances, reduce site productivity by reducing soil organic matter and associated nutrients. Two complimentary studies in the Gulf Coastal Plain of the southeastern US were designed to test whether harvest intensity (level of biomass removal) could have a negative long-term impact on site productivity. Harvesting tree crowns in addition to the merchantable bole had a negative impact (18%) on pine biomass accumulation by age 7–10 years on 15 of 19 research blocks. Sites at risk of harvest-induced reductions in productivity were relatively unproductive prior to harvest and had low soil phosphorus (P) concentrations. Intensive harvesting, fertilization, and chemical control of non-crop vegetation were all energy efficient; the additional biomass energy gained through these practices was two-orders of magnitude greater than the energy needed to conduct the activities. Harvest of slash for bioenergy in the Gulf Coastal Plain of the southeastern US has the potential to reduce productivity on infertile soils, but fertilization has the potential to restore and even improve productivity on those sites in an energy-efficient way. [Copyright &y& Elsevier]