Spruce-fir-beech mixed forests cover a large area in European mountain regions, with high ecological and socioeconomic importance. As elevation-zone systems they are highly affected by climate change, which is modifying species growth patterns and productivity shifts among species. The extent to which associated tree species can access resources and grow asynchronously may affect their resistance and persistence under climate change. Intra-specific synchrony in annual tree growth is a good indicator of species specific dependence on environmental conditions variability. However, little attention has been paid to explore the role of the inter-specific growth asynchrony in the adaptation of mixed forests to climate change. Here we used a database of 1790 treering series collected from 28 experimental plots in spruce-fir-beech mixed forests across Europe to explore how spatio-temporal patterns of the intra-and inter-specific growth synchrony relate to climate variation during the past century. We further examined whether synchrony in growth response to inter-annual environmental fluctuations depended on site conditions. We found that the inter-specific growth synchrony was always lower than the intra-specific synchrony, for both high (inter-annual fluctuations) and low frequency (mid-to long-term)

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.

The development of technology and the means of labour in the technological process of forest harvesting in FBiH mainly depends on the factors related to the specific manner of forest management. The dominant share of mixed tall forests with natural regeneration, the selective manner of management and rather difficult natural conditions have resulted in the application of the cut-to-length method and to a lesser extent, the tree-length and semi-tree-length methods. On the basis of expert classification of the development phases in forest harvesting, it can be noted that wood assortment production in FBiH is currently partially mechanised. With the aim of defining measures for increasing productivity, lowering the costs and a greater humanisation of work, there has been an analysis of the current state of the means of work in all three phases of forest harvesting. The analysis included the following parameters: number of means in different phases, the type, the average age, ownership and technical planned obsolescence. All the data were collected through a survey which included all stakeholders (cantonal forest companies and private contractors). The results showed a satisfactory state only when chainsaws are concerned, i.e. the rather cheap tools. Other equipment (adapted tractors, skidders, trucks, etc.) has largely reached planned obsolescence. Their old age results in a low level of utilisation, i.e. an insufficient amount of working hours per year which eventually leads to a decrease in productivity and increase in expenses. Based on the data, it can be concluded that it is necessary to begin the process of new mechanisation procurement and the replacement of existing, time-worn and technologically obsolete machines with new ones. At the same time, it is clear that, in the conditions of low availability of investment capital and cheap labour force, this has to be a gradual process. In relation with this, the process should start in the most expensive phase - timber extraction, i.e. the phase in which the economic efficiency is unquestionable.

No abstract

Mechanisation used in forest utilisation has an impact on the occurrence of damage in stand and on forest land. The research in this work had the objective of determining damage on fir trees and other tree species during felling and processing of trees and their skidding using the forest cable-skidder. The research wasconducted in mixed beech and fir forests in the area of FMA “Glamočko”, M.U. “Hrbinje-Kujača”. The following data were gathered on damaged trees: tree type, breast height diameter, economic importance of the tree, amount of damage, location of damage, cause of damage, types of damage. Damage was recorded on a total of 305 trees, 133 trees of silver fir (Abies alba), 130 trees of European beech (Fagus sylvatica), 33 trees of European spruce (Picea abies), 8 trees of rowan/mountain-ash (Sorbusaucuparia) and one tree of sycamore (Acer pseudoplatanus). The overall damage intensity was 18.7%, but together with the old damages, the overall number of ‘wounds’ is 496. According to this, when the old damage isalso considered, then the intensity of damage amounts to 30.6%. The largest amount of damage is in the diameter sub-class ranging from 10 to 14.99 cm. According to the cause of damage, the largest amount of damage occurred during the wood extraction phase (217 trees), while during the felling phase, 88 trees or 29% were damaged. Since the wood extraction phase is divided into the winching and skidding phases, the total number of damaged trees during the winching phase amounted to 157 or 52%, while during the skidding phase, the number of damaged trees was 60 or 19%. To reduce damage to the trees during following operations in forest utilisation, it is necessary to perform more frequent training of all employees working on forest utilisation, to increase controls in execution of operations during forest utilisation, modernise machines used during forest exploitation, and in quality manner open compartments with forest road infrastructure.