Productivity and Costs of Three Harvesting Methods

Abstract

Three stands were harvested by either clearcut, shelterwood, or single-tree selection methods. The single-tree selection method consisted of a light thinning in an even-aged stand as the initial basal area reduction cut required to convert the stand to uneven-aged structure. The contractor used two skidders (one grapple, one choker) and production chain saws to harvest all three tracts. Harvested sites were all similar in slope (10-15%), average dbh (12-14 in.), and preharvest number of stems by dbh.In the felling study, fell, walk, and limb-top time were all greater for the single-tree selection method. Time to process a tree was lowest for the clearcut, intermediate for shelterwood, and highest for single-tree selection method.For skidding, bunch building time was highest for the single-tree selection and lowest for the clearcut method. Average volume per cycle was consistently higher for the grapple skidder than the choker skidder; volume per cycle was lowest for the single-tree selection and highest for the clearcut method for both skidders. Time per cycle was consistently lower for the grapple skidder than the cable skidder. Time per cycle was lowest for the clearcut and highest for the single-tree selection method.Factors that affected felling productivity (in decreasing order) were: dbh of harvested stems, intertree distance, and method of harvest. Factors that affected skidding productivity (in decreasing order) were: skidder type, pull distance, average volume per cycle, and the method of harvest.Costs of felling and skidding were highest on the single-selection stand and lowest on the clearcut stand. Total percentage of stand area trafficked was lowest for the single tree stand. However, the total area disturbed to meet a wood procurement budget was lowest for the clearcut and highest for the single-tree method. South. J. Appl. For. 18(4): 168-174.