Volume 65 (2019): Issue 1 (March 2019)

Global climate change also influences the forest damaging agents occurrence and thus a forest health. Forest trees that are damaged by agents are in managed forests processed by salvage felling. The amount of an annual salvage felling represents the occurrence of a damaging agents occurrence in a certain year. In 2015, the area of forests in Slovakia reached 2.014 mil. ha. Within the 20 years (from 1998 to 2017), the total felling reached 162.52 mil. m³, out of this 47.99 % were ascribed to a salvage felling. Abiotic agents were the most damaging agents (42.28 mil. m³ of damaged wood), out of it a wind was the most important one. Biotic damaging agents were the second important group (32.165 mil. m³), whereas bark beetles on spruce were the most important. The third group and the less damaging one was anthropogenic agents group (3.555 mil. m³) with an air pollution as the most important damaging agent. There was no statistically significant difference in the volume of processed trees within salvage felling caused by abiotic and biotic damaging agents. However, these two groups caused significantly higher damages than the third group of anthropogenic damaging agents. There were two major wind damages, Alžbeta in 2004 and Žofia in 2014 with damaged wood 5.3 mil. m³ and 5.2 mil. m³, respectively. They occurred in southern, central and northern part of Slovakia. As damaged wood was not processed from strict nature conservation areas, the secondary damaging agents, mostly Ips typographus on Norway spruce reproduced as much that after some years it cumulatively reached or even exceeded damages from those two major windthrows episodes.

The incidence of salvage felling is a significant indicator of stands‘ health and stability. Health is mainly indicated by biotic and anthropogenic factors, while abiotic effects are primarily an indicator of a stand’s stability. All these factors influence each other and subsequently they can result in salvage felling. For the Czech Republic, there have been relevant data for the period since 1964. Actually, recent data cover approximately 70% of the Czech Republic´s area in the twenty-year period assessed in this text. During this period, the volume of salvage felling amounted to 89.2 million m³ which represents 28.4% of total felling in this period. The largest share is caused by abiotic effects (18.6%), next by biotic agents (9.6%) and anthropogenic are only responsible for 0.2%. In the last two years, the volume of salvage felling caused by biotic agents was higher than the volume of salvage felling caused by abiotic and anthropogenic agents for the first time. In terms of biotic agents, almost the whole volume is represented by bark beetle wood as a result of spruce stands infestation by the European spruce bark beetle – Ips typographus (L.) and double-spined bark beetle – Ips duplicatus (Sahl.), and to a small extent also by other species of bark beetles on spruce, pine and occasionally other wood tree species. In the last three years, mainly the incidence of the Ips typographus L., has concentrated in North Moravia and Silesia. Currently, it is also spreading in South Moravia and Bohemia and in districts along the state borders with Austria and Germany, with the most serious situation in this region being the one in the Bohemian-Moravian Highlands.

The negative effect of air pollution on mountain spruce stands culminated in the 70s – 90s of the 20^th century, when an extensive dieback and disturbance of stands occurred in the Krkonoše Mts., the Czech Republic. Dendrochronological analysis was used on ten permanent research plots established in 1976–1980 to document the dynamics of radial increment of Norway spruce (Picea abies [L.] Karst.). The objective was to determine the effect of SO₂, NO_X and O₃ concentrations and precipitation and temperatures on spruce radial growth in climax forests, waterlogged forests and cultivated forests. The results document the strong depression of diameter increment in the period 1979–1991 caused by synergism of climatic extremes and high SO₂ pollution in the 80s and 90s of the 20^th century. After 2000 climate had prevailing effect on radial growth. Spruce increment was in positive correlation with temperature, particularly with temperature in the growing season and annual temperature of the current year. In general, temperature had a more significant effect on increment than precipitation, mainly in climax and peaty spruce stands. Diameter increment was in significant negative correlation with SO₂ and NO_X concentrations in all types of stands. Overall, peaty spruce stands were the most vulnerable to air pollution stress. Low radial increments were caused also by climate extremes, historically by strong frosts and winter desiccation in early spring, nowadays in time of climatic changes by extreme drought. Spruce stands have the ability of quickly responding by tree-ring width to both negative and positive impulses related with air pollution and climate.

Numerous prognoses indicate that climate change will manifest itself in extreme climatic conditions. Therefore, it will be of high importance to know in what extent can plant communities and certain species adapt to altering environmental conditions. Our examinations were implemented in stands of sessile oak common in the Carpathian Basin. The reason behind it has been that, according to climatic models, the realized niche of this species can be reduced by 80% in some regions by 2050. Examinations were made in 3 points of an approximately 400 km long (East-West) transsect crossing the Carpathian Basin: 3 submontane regions of a subatlantic, a continental and a subcarpathian mountain were involved with 5 age groups in each regions. Health status examinations of sessile oaks have been completed by using FAKOPP 3D acoustic tomograph. Among the three venues trees of the subatlantic area were the healthiest; here, the 100 years old age group showed the lowest deterioration, only 0.68%. The most severely deteriorated stands occur in the continental region where the value in the 60 years old age group reached 4.24%. It seems that, besides annual precipitation, the method of planting also influences the health status of stands, since considerable differences could be observed between coppice and seedling stands.

In the system of logging machines, a factor such as the density of wood affects all components of the system. However this dependence can be more noticeable in the performance of wood felling, where logging machines have approximately the same saw body, such as a chain saw. In this regard, the problem of determining the dependence of the chainsaw on the density of wood, substantiation of effective options for the number of chainsaws in the assortment and whiplash method of logging is quite relevant. In the Far East of Russia, in particular, in the Amur region, the forest growth conditions are different from the western ones and therefore the properties of the woof differ from the generally accepted ones. The article describes forest growth conditions that influence the properties of the wood in areas of the Amur region. Using the method of density determination, the density of larch, pine and birch were studied first time in the areas of the region. The dependence of the density on humidity, age, species, season of the year and the area of growth was found out. The research results showed that in the Amur region at a humidity of 70% the density of larch varies from 745 to 1 089 kg m⁻³, pine from 435 to 1 081 kg m⁻³, birch from 403 to 878 kg m⁻³.

Heterogeneity in the tree trunks’ shapes and quality is not often reached fully using raw material potential in grading processes of tree and stand and the following sawmill processing.

Therefore, optimization of given processes is a current topic of research and is part of the operational practice. In the contribution we submit a survey of solving the given problems in the European and Slovak conditions. A significant impulse for solving problem at a new level is a significant progress in the field of industrial computed tomography. New and fast CT scanners have been developed and they enable to increase valuation by 15% in coniferous trees and by 24% in broadleaf trees. In the contribution we analyze period of returns of CT scanner’s implementation into the sawmill process within Slovak context for small, medium-sized and big sawmills. Results show that period of returns for big sawmills is approximately for years, for medium-sized sawmills is eight years when processing coniferous softwood or three to eight years in case of broadleaved processing. In the final synthesis we present a concept of interlinking the 3D scanner and technologies of laser woodcutting with the outcomes allowing to optimize stand grading and maximize profit of the given raw wood in the sawmill processing.

The paper deals with sawmilling and timber processing capacities in the territory of the Czech Republic. Selected operations are sawmills with the annual processing capacity over 10,000 m³, further divided into groups by the annual volume of processed raw material. In total 35 companies, which were chosen at random, were compared based on the indicator of value added per employee. The results show that the value added considerably differed not only among the groups but also within the individual groups of sawmill establishments.