DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 3-4/2020 str. 40     <-- 40 -->        PDF

damage on the stem, seedling, young growth and forest land and pollution of water during forest operations with consequences that are shown in the reduction of beneficial forest functions (Petreš 2006).
Various factors havean impact on the damage of the stand during forest operations, and the most important ones are: characteristics of the terrain and stand, types and characteristics of technical means, technology and work method and man’s attitude man toward the work.
Mechanisation which is ever more frequently used in the technological process of forest utilisation impacts larger effectiveness during utilisation. However, due to the use of mechanisation, there has been a significant increase in damage occuring in the stand and on forest land. Damage on standing trees in the stand most often appears in the felling and wood extraction phases. During the felling phase, damage occurs on surrounding trees mainly on their crown and in form of crushing of tree bark which is confirmed in the research by Danilović et al. (2015).
During the skidding phase,great damage appear that has the toughest consequences on the rest of the stand. In this phase of the extraction of wood assortments by tractors, the wood mass gets stuck to standing trees which caused bark to peel off and leaves a possibility of penetration of pathogens. This is confirmed in the research by Vasiliauskas (2001).
Stem and butt end damage is economically the most harmful because mainly the most valuable part of the stem is damaged. This was confirmed in the research by Behjou (2016).
Examination of damage, that appears during the felling and processing, extraction and transport phases of wood mass, was dealt with by many researchers (Kaminsky 1984; Dvorak and Iordache 2010; Badraghi et al. 2015).
Damage that occurs on trees is largely caused by density of roads, i.e. the distribution of the primary and secondary road network (Ostrofsky 1988).
Damage to trees of fir and other species during the skidding phaseusing the Timberjack 240C skidder in variable aged stands of Gorski kotar was researched by Sabo (2003). According to this author, a series of indicators on damage and wounds to the stand confirm the assumption that stand and terrain conditions are determining factors of damage, with equal other conditions – technology and methods, work assets and work executioners.
Martinić (1991) determined, through the analysis of damage in the stand of beech, sessile oak and oriental hornbeam, that the largest amount of damage occurs during extraction of wood mass (53%),and regarding the place of damage, most damage appears on the root collar.
Damage on tree parts was researched by Tavankar (2013),who determined that most of the damage appears on a height of up to one meter. According to the same author,a larger amount of damage appears during the extraction of wood mass (5.2-11.1%) compared to felling (1.4-3.4%).
Solgi and Najefi (2007) determined that the largest amount of damage, during forest utilisation using skidders occurs on the root (41%) in beech and horn beam forests in Iran.
During felling,crowns of neighbouring trees are mostly damaged, while during skidding of wood mass, the root system is mostly damaged. Also, during the same research it was determined that the most common width of the damage ranges from 50 to 200 cm² (Danilović et al. 2015).
According to research by Hartsough (2003), the largest amount of damage is in the lower diameter sub-class, confirmed by Zahirović et al. (2016).
According to the research by Zahirović et al. (2016), in forests of fir and spruce it was determined that trees with one damage each appear the most. It has also been determined that spruce has more damage to roots and stem compared to the crown, while in the case of fir it is vice-versa. Based on the same research, authors reached the data that say that most damage appeared on the stem (71.6%), while crown had 18.8% and root collar had 9.6%. Mentioned by the same author, in forest of fir and spruce it is determined that average size of damage on fir was 607.14 cm², and on spruce was 407.27 cm² during felling with chainsaw and extraction of wood mass using a skidder.
Damage on trees most favourably affected the occurrence of disease on those trees and represent the biggest danger to the surrounding healthy trees (Vasiliauskas 2001).
Akayet et al. (2004) propose to synchronise felling with characteristics of forest, type of mechanisation and intensity of felling, including some other factors that affect the effectiveness of work.
Erogluet et al. (2009) state that technique and technology of work have to be focused on the reduction of damage tothe remaining trees, young growth and land/soil.
During mechanised skidding of wood assortments, in addition to stand damage (standing trees and young trees) there is also damage to the environment (soil, water, discharge of pollutants, etc.). This and similar research represented the subject of study for numerous authors (Calcante et al. 2018; Ilintsev et al. 2018; Karaszewski et al. 2018; Marusiak and Neruda 2018; Solgi et al. 2018; Labelle and Lemmer 2019; Solgi et al. 2019a; Solgi et al. 2019b.).
Problems that appear during forest utilisation are present in Bosnia and Herzegovina. Wood extraction by animals is less and less present, unlike extraction by cable-skidder with