Feasibility of utilizing small diameter southern pine for biomass in the Virginia Coastal Plain
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New or retrofitted wood-fired energy plants have increased demand for woody biomass in the stateof Virginia. Loblolly pine (Pinus taeda) commonly serves as a feedstock for these energy plants. Pulpwood conventionally requires a minimum diameter of 4 inches diameter at breast height (DBH) for merchantability, whereas a minimum merchantable diameter for biomass is currently undefined. A harvesting case study was completed during the first thinning of a 15 year-old loblolly pine stand in the Virginia Coastal Plain to determine production rates and costs while harvesting densely stocked small diameter loblolly pine stems (< 4 inches DBH). Pre-harvest stand attributes included a quadratic mean diameter (QMD) of 4.2 inch DBH, an average
density of 1,377 stems/acre, and an average volume of 73.7 green tons/acre. Post-harvest 34.0 green tons/ acre remained. Harvesting equipment included three Tigercat 718 feller-bunchers, two Caterpillar 535C skidders, and one Peterson 4300 chipper. Elemental time studies conducted on the feller-bunchers, skidders, and chipper determined individual machine productivity rates of 30.8, 23.4, and 83.7 green tons/productive machine hour (PMH), respectively. Use of the Auburn Harvesting Analyzer determined an on-board truck cost of $16.52/green ton and a total cut-and-haul cost of $23.46/green ton. Regional average prices for in-woods chips indicate the harvest was not economically feasible.