The impact of a small forwarder with the wheeled chassis, tracked-wheel chassis, and tracked chassis traveling on the soil profile was studied. The three chassis types were assessed for the influence of the loading of forwarder cargo space and the degree of tire inflation on induced specific and actual pressures of tires on the soil surface. Penetrometric resistances of soil profile and rut depths in the forwarder driving track were measured. The effect of a layer of logging residues in the forwarder driving track on the size of induced actual pressures was determined. The practice of determining the impact of forest machines on the soil surface by means of a specific tire pressure does not have a full informative value. In the forwarder wheeled chassis, maximum values of actual pressures exceeded specific pressures established numerically by up to 203%. Average values of actual pressures could be reduced by 45% by reducing the pressure of tire inflation, by 70% with the use of tracks, or by 49% by traveling on the layer of logging residues. As compared with the wheeled chassis type, the tracked type of the forwarder chassis induced actual pressures to lower by 81% and the rut depth after ten forwarder passes was smaller by 50%.

Logging residues offer a significant contribution to the economical profitability and sustainability of forest-based resources. It is always desirable to optimise the harvesting and extraction method to improve the economy of the process along with ensuring sustainability from an environmental point of view. This study compares two harvesting methods, i.e., conventional cut-to-length (CTL) followed by harvesting residue extraction for energy and an integrated harvesting method combining CTL with harvesting residue pre-piling by the harvester followed by the extraction of both timber and logging residues for energy. The study was carried out in spruce stands (Picea abies (L.) Karst.) in South Moravia (Czech Republic) at Pozořice and Kuničky. Two methods utilized by harvesters and forwarders were compared. The first case was a conventional CTL method when trees are felled, delimbed, and cross-cut by the harvester. The resulting logs are pre-piled and then transported by the forwarder. In this case, the harvesting residues remain in the stand. The method does not involve utilizing harvesting residues such as brash mat on striproads but rather extracting them in an independent step as an energy source. In the second case, the resulting harvesting residues are piled up by the harvester to be later extracted by the forwarder. Such extracted harvesting residues are stored at the roadside for seasoning and future comminution. The aim was to obtain input data for internal analysis of a private entity contracting in a logging operation. The client demanded that the increase in time needed for the production of one timber unit with simultaneous harvesting residue preparation be measured. By our estimates, the integrated harvesting method required 33% more (harvester) and 16% less (forwarder) time compared to the alternate method for the extraction of harvesting residues, which in turn results in approximately 8% longer total operational time for the complete operation.

The work of chainsaw operators in the forest environment is a hazardous activity associated with great physical effort, inappropriate posture and significant strain on individual body parts. The aim of this study was to gather and evaluate data on the fatigue of individual body parts of professional chainsaw operators felling trees in the forest. The research focused on twelve body parts (eight in the upper half and four in the lower half of the body), each divided into the right and left parts. Based on the questionnaire method, 170 professional chainsaw operators working in the Czech Republic participated in this research. The questions in the questionnaire were divided into two sections, and the answers were used to draw diagrams that were consecutively analysed and quantitatively characterised based on descriptive statistics. The research results indicated that the most stressed part of the operator’s body at the end of a shift was the lumbar region. The second most stressed body parts were the wrist and hands. In contrast, the neck was the least stressed part of the operator’s body.

The work of tree climbers is a hazardous activity during which many risks of occupational accidents must be faced. Numerous injuries happen during the performance of this professional activity. This is why our research was conducted, and the principle of which was to gather and evaluate, on the basis of the questionnaire method, injuries occurring to tree climbers during their work. An anonymous online questionnaire was prepared in order to obtain data about the rate of accidents recorded amongst tree climbers working in the territory of the Czech Republic. There were 121 tree climbers participating in the collection of data. The questionnaire was divided into seven sections, each section including questions focused on possible injuries related to the work of tree climbers and first aid. Answers of respondents indicated that the highest number of injuries were caused by cutting with the manual saw. Burns caused by the power saw and damage to eyes by sawdust or dust during sawing followed. The results also showed that nearly 30% of tree climbers work alone, and 47% of tree climbers collaborate with a ground worker who is not able to rescue them from the tree in the case of an exceptional unexpected situation. The research also revealed surprising results as to carrying first aid kits. Only 62% of tree climbers have a personal first aid kit on them in the tree crown. However, a positive finding appears in the fact that 75% of tree climbers are graduates of some medical course.

Open access peer-reviewed chapter

Results obtained from the research study focused on the functional parameters of five saw chains tested on a test bench equipped with an electrically driven chain saw brought a number of findings. One of the most important of them is the significant difference between the cutting rates of round and square chains. The cutting rate of square chains R = 27.9 cm 2 •s-1 is about 12% higher than the cutting rate of round chains. The influence of the chain construction on the chain cutting rate was conclusively demonstrated-the cutting rate of chains with a square profile is higher than the cutting rate of round-profile chains. It was further found out that although the specific energy E m = 77.8 Ws•cm-2 is by ca. 7% lower in the square chain than in the round chain, Student's t-test did not reveal any statistically significant difference in the data on the specific energy consumption of round and square chains, i.e. the influence of the chain design on the specific energy consumption of the chain at cutting was not clearly demonstrated. Other findings, for example, showed that working with a loose saw chain on the guide bar impairs parameters of the chain operation or that energy demands of cutting with the saw chain are directly proportional to wood density (hardness) and increase with the decreasing wood moisture. Yet another finding was learning the energy flow structure, which indicated that 46% of total power input is consumed by the electric motor alone for its operation while only about 7% goes for driving the chain movement along the bar (without cutting) and power input required for cutting is approximately 46%.