Quality assessment of pine wood harvesting by residue inventory using line intercept cluster sampling

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ABSTRACT Inadequate wood harvesting can lead to a loss of marketable biomass for energy purposes and affect subsequent forestry operations. Therefore, woody residue inventory tools are essential for guiding forest managers and ensuring operational wood harvest quality. In this study, we aimed to propose and evaluate the line intercept sampling in systematic clusters to inventory wood cutting and chipping residues. The study was carried out in a 15-year-old Pinus taeda L. stand under clearcutting by a full-tree harvesting system. This wood harvesting system was composed by a directional feller, a skidder and harvester machines, followed of a forest chipper which produced the residual biomass for energy purposes, in which residue pieces with small-end diameter equal to or greater than 4 cm were considered for commercial energy purposes. Residue inventory was carried out after wood harvesting and chipping operations through 10 clusters composed of four lines with 15.71 m each. These clusters were randomly distributed in which the residue diameters and lengths were measured. The number of woody pieces per hectare and their volume estimations were performed aiming at 20% sampling error. Confidence intervals with a 95% significance level were from 21,054 to 37,978 woody pieces per hectare, and from 16.03 to 26.12 m3 per hectare, in which only 13% of the woody pieces were above the commercial limit diameter. Line intercept sampling in clusters has proven to be efficient for quality control of wood harvesting and chipping operations.