Comparison of productivity of standard and accumulating forwarder grapple in thinning

Abstract

The aim of the study is to evaluate the impact of the accumulating grapple on forwarding productivity in thinning in comparison to the standard grapple and to evaluate potential areas of application of accumulating grapples. Trials were conducted in 3 coniferous stands on nutrient-poor mineral soil with the total area of 15.2 ha. Two work methods are compared in the study - forwarding with a John Deere 1110D ECO III forwarder, equipped either with an accumulating grapple (first method) or a standard grapple (second method). According to the study results the use of the standard grapple results in slight increase of productivity (2.3 % per load and 1.4 % per m3 of logs). The difference is not significant, however additional trials are recommended to compare both grapples in more fertile forest stands with a larger number of assortments and extracted volumes, also in regenerative felling. According to the study results the prime forwarding cost is 9.4 EUR m-3 if the standard grapple is used and 9.5 EUR m-3 if the accumulating grapple is used. The difference is not significant. No significant difference is found between the methods also in terms of damages to the remaining trees.