engleski

Productivity of chainsaw felling and processing in selective forests of Croatia

In Croatia, one-worker chainsaws were introduced in the early sixties. Felling and processing has been partly mechanized and since then trees are felled and processed into timber assortments motor-manually. Fully mechanized harvesting is used mainly just in forest cultures and plantations, but in all natural forests, including the selective ones, chainsaw is still a major means of work for felling and processing. The majority of selective forests in Croatia grows in the region of Lika and Gorski Kotar. Precisely the region of Gorski Kotar is the most afforested part of our country. Some 75% of its surface is covered with forests, so the inhabitants of Gorski Kotar are traditionally and inseparably linked to the forest and forestry. The study was conducted in selective felling site to determine the productivity of workers in the motor-manual felling and processing of timber assortments. Snap-back chronometry method was used for recording time consumptions of individual work elements (walking to the tree, felling, processing, scaling) and delays. Net volume of produced timber assortments was measured for all investigated trees. A regression analysis of dependence of individual work elements time consumptions on the trees DBH was conducted and a productivity model based on an eight-hour work-time was constructed. During the seven days of research (1944.72 min), 1109.75 min (57.06%) of effective time and 834.97 min (42.94%) of delay time was recorded. Analysis of delays provided the allowance time as 61.21% of effective time. In the structure of delay time the forefront was the delay due to rain, but the same, given the climatic characteristics of the study area, was recognized within allowance time. A very strong correlation between the DBH and time consumption for felling of trees and for processing of timber assortments was found. The projected daily output of felling and processing ranged from 9.65 m3 for trees of DBH class 17.5 cm to 45.89 m3 for trees of DBH class 72.5 cm. Based on a calculative direct daily cost of felling and processing the unit cost was determined. It ranged from HRK 13.42/m3 (€ 1.81/m3) for trees of DBH class 72.5 to HRK 63.83/m3 (€ 8.59/m3) for trees of DBH class 17.5 cm.

selective forest; motor-manual felling and processing; productivity; cost

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