engleski

Optimization of Timber Forwarding from Pedunculate Oak Stands after Salvage Thinning

The secondary productivity in forestry is also called technical productivity. It depends on inputs of forest operators and used machinery, and it is especially significant in the investigation of forest operations. The aim of a high quality organization of wood assortment production is to increase the yield and reduce costs. This can be achieved by the optimization of the work process. In the area of the Croatian lowland forests, which are even-aged, forwarders are mainly used for the extraction of roundwood. The use of forwarders implies the assortment method of wood processing, so that after motor-manual felling and processing by chainsaws, wood assortments are scattered on the ground of the felling site. Apart from forwarding timber from main felling and late thinning, these vehicles are also used for forwarding timber after salvage thinning. The research involved comparative analyses of data collected during monitoring timber forwarding at two working sites (A and B). Both felling sites had similar terrain and stand characteristics – they were 100-year old pedunculate oak stands. Salvage thinning was carried out (damaged, dead and decayed trees). Felling density was 11.10 m3/ha at both felling sites. When marking the trees for felling, they were located with the help of a GPS device, and their DBH was measured. After felling and processing, time study was performed during roundwood forwarding by snap-back chronometry method. The characteristics of the forwarded roundwood have been taken over from the IT system of the company that keeps records of the processed assortments. Vehicle travel was recorded by a commercial GPS with the external antenna installed on the vehicle cabin. In the first case (working site A) the driver of the forwarder had no information on tree locations, while at the working site B, guidance was provided to the marked trees (expected timber loading points) with the aim of shortening the vehicle travel and reducing soil damage. The results are in favor of the work system applied at the working site B. In this case, the vehicle travel distances were shortened and on average higher load volumes per work shifts were recorded. The above said resulted in lower time consumption required for travel during loading as well as in lower time necessary for the loaded vehicle travel. Considering the results of this research, it can be concluded that in conditions of lower harvest intensity (salvage thinning), by an adequate work preparation (and namely locating all marked trees and informing the forwarder driver of these locations), the area of the forest stand soil exposed to damage can be reduced, the forwarder productivity can be increased and unit costs can be lowered.

forwarder; productivity; costs; salvage thinning; pedunculate stands

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