High tonnage harvesting and skidding for loblolly pine energy plantations
The southeastern United States has a promising source for renewable energy in the form of woody biomass. To meet the energy needs, energy plantations will likely be utilized. These plantations will contain a high density of small-stem pine trees. Since the stems are relatively small when compared with traditional product removal, the harvesting costs will increase. The purpose of this research was to evaluate specialized harvesting and skidding equipment that would harvest these small stems cost efficiently. The feller-buncher utilized was a Tigercat 845D with a specialized biomass shear head. The skidder was a Tigercat 630D equipped with an oversized grapple. This equipment was evaluated in a 4-hectare stand with characteristics of a southern pine energy plantation. During the study, the feller-buncher achieved an average production rate of 47 green tonnes/productive machine hour (gt/PMH) and the skidder had an average production rate of 112 gt/PMH. A before-tax cashflow model was used to determine a cost per ton for each machine. The feller-buncher costs were $3.85/gt over a 10-year life span, whereas the skidder costs were $1.95/gt over the same 10-year life. The results suggested that the current system working in a southern pine energy plantation could harvest and skid small stems for approximately $5.80/gt.