Background and Purpose: Bark thickness and its share in the volume of roundwood are the most important characteristics of the bark, particularly in the process of timber harvesting, and during scaling of processed logs. Therefore it is very important to have at disposal relatively accurate data regarding these characteristics of bark for particular tree species. The main goal of this paper is to investigate the thickness of the bark and its share in the volume of roundwood of Norway spruce. Materials and Methods: The research was carried out in the area of the Canton 10 of the Federation of Bosnia and Herzegovina and it encompassed 393 trees of Norway spruce from 10 cm to 115 cm of thickness at breast height. Measuring of the mean diameter and double thickness of bark was conducted by section method. In total, 4,647 diameters and bark thicknesses were measured in different relative lengths of stems or in average 10.6 measurements per one stem. Results: As an optimal model for the evaluation of double thickness of the bark of Norway spruce depending on mean diameter of roundwood the function with designated determination coefficient of 0.7142 was selected. The obtained results have confirmed the previously defined relations of investigate characteristics, which are as following: a) with the increase of mean diameter of roundwood (section) double bark thickness is increased from 9.26 mm (thickness class 12.5 cm) to 31.65 mm (thickness class 92.5 cm); b) with the increase of mean diameter of roundwood the share of bark in its volume decreased from 14.26% (thickness class 12.5 cm) to 6.73% (thickness class 92.5 cm). Conclusions: By the actual method of estimating bark thickness or the share of bark in the volume of roundwood of Norway spruce in the forestry of the Federation of Bosnia and Herzegovina a significant error was created which increases with the increase of mean diameter. The obtained results point to the necessity of investigation of these bark characteristics in Bosnia and Herzegovina and represent an inevitable starting point for making adequate tables of bark thickness and its percentage share in the volume of roundwood of Norway spruce.

SEEFOR - South-East European Forestry

The negative influence of timber harvesting on the forest environment is reflected through damage to the residual trees, regeneration, and forest soil. Considering that skidding, a popular extraction method, can cause substantial and severe damage to the remaining stand, the aim of this research was to determine damage to residual trees during skidding by an LKT 81T cable skidder, including oxen bunching. The research was conducted in eastern Bosnia and Herzegovina, in an uneven-aged mixed fir (Abies alba Mill.) and spruce (Picea abies L.) forest with pine (Pinus sylvestris L.) on limestone soils. Tree felling was conducted using a Husqvarna 372 XP chainsaw. Extraction operations caused damage to 6.31% of the residual trees in the stand. The most damage was “removed bark” (65.34%) and occurred on the lower parts of the tree, the butt end (55.11%) and root collar (32.39%). The average size of the damage was 197.08 cm². A statistically significant correlation was found between the damage position and the diameter at the breast height (p < 0.05) and the damage position and damage size (p < 0.01) by Spearman correlation analysis. The conducted analysis by the chi-squared test showed that there is a statistically significant difference in the proportion of damage for trees with different distances to the nearest skid road (p = 0.0487), but the share of damaged trees did not decrease by increasing the distance from the skid road.

Energy Chains Optimization for Selection of Sustainable Energy Supply | InTechOpen, Published on: 2016-06-30. Authors: Srđan Vasković, Petar Gvero, Vlado Medaković, et

The paper deals with the analysis of the fuel consumption of skidders during timber extraction from thinning of even-aged beech forest on mountain terrain. Fuel consumption research was conducted on the Ecotrac 140V cable skidder over 8 working days at the same worksite during real timber extraction work. The worksite was organized so that the empty skidder traveled uphill, and when loaded, it moved downhill. The skidder was equipped with measuring devices for collecting data from sensors, the motor, and data transfer. The key parameters measured include total fuel consumption (mL) and skidder GPS position, while slopes of skid trails and load volumes were measured directly on terrain. Fuel consumption (L, L/m³) was determined per work cycle and work cycle elements. The highest fuel consumption occurred while driving the unloaded skidder, accounting for 38% of the total. This is primarily because fuel usage during skidder movement is significantly affected by factors such as skidding distance, slope, and skid trail conditions, especially since the unloaded skidder was moving uphill. Guidelines for better and more efficient organization of work and reduction in fuel costs are presented, and the suitability of the skidder and harvesting system are considered based on the results of fuel consumption.

UDK 630*38:551.311.21 625.711.84:551.311.21 Tractor roads are often, due to un-implementation of appropriate rehabilitation measures, exposed to erosion processes of various intensity. These processes can be particularly expressed upon completion of forest harvesting works if natural conditions also have such character which favors intensification of erosion process. Intensification of erosion processes on tractor roads in post-exploitation period most often occur in cases when surface water appears on ruts. More intensive coverage occurs in cases when tree crowns do not cover tractor roads, i.e. if larger opening (of forest crop) is in close vicinity of tractor road, which enables larger presence of light and more intensive vegetation growth. This document applies erosion process intensity degree method and assessment of degree of coverage or coverage by litter. For assessment we used a scale from 1 to 5 (REBULA, 1991). Erosion intensity degree on observed locations goes from 1,86 to 3,73. Coverage of tractor roads by grass vegetation or coverage by litter is in range from 4,91 to 1,86.