Utilization, Cost, and Landowner Return from Whole-Tree Chipping Young Loblolly Pine Thinnings

Abstract

In the southern US thinning loblolly pine to produce whole-tree and clean chips for energy is likely to compete with thinning for roundwood pulpwood as bioenergy markets expand. Since chip harvests have higher yields per hectare and can tolerate smaller tree size, comparisons between harvesting costs and associated landowner returns are difficult to make. We completed a gross and continuous timing study on a 67 hectare whole tree chip harvest (skidder, 2 feller-bunchers, disk chipper, and tracked loader) in southern Alabama in order to compare production rates, harvest costs, and landowner returns. The stand was 12 year old loblolly pine established on retired crop land with an average total biomass volume of 195 green tonnes (gt) ha-1 and average stem volume 0.22 gt tree-1 and 0.19 gt tree-1 for harvested trees. The whole-tree pine chip harvest totaled 98 gt ha-1 compared to estimated roundwood stem volume of 48 gt ha-1 and clean chip volume of 73 gt ha-1. Machine production averaged 49.8 gt PMH-1 for felling and 61.7 for skidding and 72.8 for loading, but loader production was limited by transportation and market availability. On average the crew produced 332 gt each 10 hour shift and skidding would have limited production at 392 gt. Simulations generated from continuous timing data were used to compare harvest costs and potential landowner revenue from the site for whole tree chips, clean chips and roundwood pulpwood.