Harvesting Biomass to Improve Low-Value Beech Dominated Hardwood Stands in Maine
Feller-buncher productivity and residual stand damage were evaluated for a mechanical whole-tree harvest removing pulpwood and non-traditional biomass (energywood) from natural hardwood stands dominated by small diameter, diseased, beech (Fagus grandifolia Ehrn.) in central Maine. Two trail spacings (18.3 m and 12.2 m) were tested to determine if modified harvesting practices could improve the productivity of a tracked, swing to tree, feller-buncher. Residual stand damage was evaluated following the harvest to assess the relative impact of harvesting and skidding operations at both spacings. Time studies were conducted on the feller-buncher to assess the influence of small-diameter stems and narrower trail spacings on the harvesting operation. Feller-buncher productivity did not differ significantly (p = 0.48) between the two trail spacings. Mean productivity (green tonnes per hour) was 74.2 using an 18.3 m spacing and 57.4 using a spacing of 12.2 m. Time study elements did not differ significantly between the two trail spacings (p-values > 0.05). The proportion of residual trees receiving one or more injuries (x¯ = 34% at 18.3 m, x¯ = 43% at 12.2 m) also did not differ significantly (p = 0.12) between the two trail spacing treatments. Based on the results of this study there seem to be no advantages to selecting one of the two trail spacing over the other.