The aim of the study was to characterize repetitive cycles of harvester operation. The study was conducted in thinning, mature and post-disaster pine stands. The sequences of the activities characteristic of harvester operation were described as time series. In order to detect the cyclic variable structure of the analysed time series, the methodology of the single spectrum Fourier analysis was applied. In standard stands, post-disaster late-thinning stands and mature stands, the existence of stable operational cycles with the length of three activities was discovered while in post-disaster mature stands additional five-activity operational phases were noted. Described in this way, the lengths of the operational cycles of harvesters working in post-disaster areas were higher by about 55% and 30% respectively, as compared to standard thinning and mature stands.

The aim of the present work was to estimate the productivity and costs of timber harvesting and forwarding during the first commercial thinning of a Scots pine stand. Three harvesting models were introduced and compared: narrow trail, wide access trail, and schematic extraction. The analyzed harvesting equipment consisted of a track mini-excavator (34 kW) with a stroke harvester head (gripping range 4–30 cm), and a farm tractor coupled to a logging trailer with a hydraulic crane. Merchantable timber (roundwood with a minimum diameter of 5 cm inside bark) was harvested from a 25-year-old planted Scots pine stand growing on a grid of 1.4 m × 1.8 m. The study showed the productivity of the mini-harvester ranged from 3.09 to 3.47 m³/PMH₁₅ (productive machine hours plus 15 min), and that of the forwarding equipment to be 4.07 m³/PMH₁₅. The analyzed model of productivity as a function of tree volume and thinning intensity was statistically significant, but the intensity parameter was significant only on plots located along wide access trails (3.7 m) and insignificant on plots located along narrow access trails (2.5 m). The distance between trees was not found to be significant. The calculated net machine costs for the forwarding equipment and track mini-harvester were EUR 36.12 and 52.47 per PMH, respectively. An increase in the usage rate of the harvesting equipment to 80% would reduce the harvesting and forwarding costs to EUR 22.07/m³.

Aim of study: The aim of this research was to analyze the workload of the operators while logging at the motor-manual level in coniferous stands undergoing two tending treatments (early and late thinning). The technologies under the investigation employed a power chainsaw, tractor equipped with a cable winch as well as delimbing and cross-cutting Hypro 450W processor.Area of study, materials and methods: The research areas were located in lowlands and in a mountain range of the Western Carpathians. In the analysis it was assumed that the heart rate at work, expressed in beats per minute, would be an indicator of the workload affecting the human organism. Based on the heart rate, three indicators were calculated: relative heart rate at work (%HRR), 50% level of heart rate reserve, ratio of working heart rate to resting heart rate.Main results: The lowest average workload (typical for light work, %HRR40%) was for the chainsaw operator in early thinning, working with a processor. Cumulative distribution function of the workload at the work station of the skidder operator was characterized by bimodality – an occurrence of two extreme, high and low, workload values.Research highlights: The workload in early thinning was higher by about 7% than in late thinning at the work station of both, the processor operator as well as the chainsaw operator working with a processor.Keywords: logging; tractor processor; heart rate; workload; cardiovascular strain.

Within the majority of forest areas where timber is harvested for industrial and energy purposes, working technologies using highly efficient multi-operational machinery and equipment are employed. The situation is different in fragmented, privately owned forests. In such forests, timber harvesting is mainly based on motor-manual technologies with a high proportion of manual labor, both at the stage of felling and timber processing and at the stage of its transport. The study aimed to characterize the work time structure of the ATV unit driver and his helper, to determine the productivity of this team, and to estimate the risk of injury during manual loading and unloading. Based on the data collected during the field research, the theoretical work time structure, work productivity and costs, and injury risk were estimated as a result of using a professional small trailer equipped with a hydraulic crane for timber forwarding, designed for aggregation with the ATV. The average, calculated productivity of timber forwarding (over an average distance of about 500 m) with manual loading and unloading was almost twice as low as the estimated average productivity of forwarding with mechanical loading and unloading using a hydraulic crane. The total unit costs (including labor costs) of forwarding with manual loading and unloading were almost threefold higher than those of forwarding using a trailer with a hydraulic crane. The use of small forest trailers equipped with a hydraulic crane not only ensures higher productivity and cost effectiveness but also allows reducing (even by several percent) the inconvenience of manual timber handling and the risk of strain of the musculoskeletal system.

Under investigation three deadwood landing yards were established - two with pine wood and one with spruce wood. Three measuring baskets were placed on each landing yard. In each basket round timbers were arranged in three test layers. In each test layer, 7 round timbers were arranged. Two cross-sections were photographed on each roller. Photographs obtained during successive trials were analyzed with the MultiScan program. Measurement work was conducted 12 times, at the beginning (month 0) and then at intervals of 6, 9, 12, 15, 18, 24, 30, 36, 42, 48 and 54 months. It was found that blue stain became invisible on the cross-sections of pine round timbers after 12 months and in spruce after 6 months. On the cross-sections of pine round timbers, it was observed that hard rot appeared only after 9 months. In spruce wood, the presence of hard rot was already evident from the month 0. In most cases, the largest areas of hard rot were found in the upper layers. In the case of soft rot on pine wood, only after 12 months were isolated cases of its occurrence recorded and in spruce wood after 6 months. After 24 months did the number of cross-sections with this rot increase sharply. Natural depreciation processes of wood raw materials due to long storage cause negative changes in its quality. However, these changes are not significant, meaning that after 54 months of the raw material being in storage, it is still mostly a full-value raw material.