No abstract

Does body posture during tree felling influence the physiological load of a chainsaw operator? Ann Agric Environ Med. 2017; 24(3): 401-405. doi: 10.5604/12321966.1235177 Abstract Introduction and Objectives. Holding determined body postures during work is connected with muscles activity. The more forced the posture, the larger the number of muscles taking an active part in holding and stabilizing the work posture. During logging, the greatest share of awkward (forced) working postures occurs in tree felling by chainsaw. Materials and Method. A group of 10 experienced fellers aged 47.5±7.3 (37 -59-years-old) was studied. Heart rate (HR) was measured during simulation of felling activity in 4 working postures: back bent forward with straight legs (stoop), back bent forward with bent legs (flexed-stoop), squat and kneeling on one knee (half-kneel). Results. The lowest value of HR was noticed for squatting -114.1 bpm, then for kneeling on one knee -116.3 bpm. HR during felling in a standing posture with straight legs amounted to 121.5 bpm and for standing with bent legs 125.3 bpm. For all studied postures the differences in average HR values were statistically significant at p<0.01. Conclusions. A working posture during tree felling by chainsaw has influence on the level of physiological workload of an operator. Standing bent forward body postures cause higher heart response than squatting and half-kneeling.

The aim of this study was to investigate the effect of season of the year on the frequency and degree of damage to residual trees caused during winter and summer timber harvesting operations in young alder stands. Analyses were conducted in pure black alder (Alnus glutinosa Gaertn.) stands aged 38 and 40 years, located in north-eastern Poland. Chainsaw logging was performed in the cut-to-length (CTL) system, while timber was extracted using an agricultural tractor with a trailer with manual timber loading and unloading. Damage caused in the stand as a result of early thinning operations was evaluated in terms of: (1) damage location, (2) wound size, (3) wound depth, and (4) the distance of the damaged tree from the skid trail. Timber harvesting caused damage in 8.3% of trees remaining in the stand. Both the total number of damaged trees (p = 0.001) and the number of trees damaged during felling (p = 0.01) and extraction of timber (p < 0.001) were greater in summer than in winter. Irrespective of the season, two-thirds of all cases of damage were caused during timber extraction, with 67.7% of damage recorded on trunks or root collars and 32.3% on roots. Irrespective of the season and the technological operation, slightly over 50% of cases of damage were small wounds of max. 10 cm 2 . The proportions of medium-sized wounds (11-100 cm 2 ) and large wounds (over 100 cm 2 ) were comparable. The majority of damaged trees (85.1%) were found in the vicinity (<1 m) of the skid trails. The frequency of tree damage near the skid trail was twice as large in summer as in winter (p < 0.001).

Accurate log processing by harvesters during bucking is of great importance if round timber is to be fully exploited for maximum value recovery. Logs that exceed the target length can cause difficulties in further processing (e.g., in the pulp industry), while logs which are too short may not be of further use (e.g., boards for pallets). It can be difficult to achieve accurate log lengths due to irregular tree trunk shapes or errors in the measurement system in the harvester head. The objective of the research was to investigate how tree species and log diameter affect bucking length accuracy. The research was carried out in a premature broadleaved stand of birch and aspen in the third age class in the Zaporowo Forest District, northern Poland (54°24′47″N, 20°8′50″E). The thinning operation was carried out in early spring before the start of the growing season and after the snow cover had melted. Trees were cut using a UTC 150-6LS harvester, equipped with a CTL 40HW harvester head designed for hardwood. Pulp wood was harvested from the trees with an intended length of 2.50 m and a tolerance of ±0.05 m. The on-board harvester computer was set to a length tolerance of between 2.46 m and 2.54 m. More than 80% of the thicker birch and aspen logs (d1/2 > 14 cm) met the target length (2.50 ± 0.05 m), while only 70% and 50% of the thinner birch and aspen logs (d1/2 ≤ 14 cm) reached the target. For top logs, a different length tolerance should be applied compared to butt logs in order to achieve higher efficiency in length accuracy.

Warmer winters may lead to changes in the hibernation behaviour of bats, such as the barbastelle Barbastella barbastellus, which prefers to hibernate at low temperatures. The species is also known for its large annual fluctuations in the number of wintering individuals, so inference about population trends should be based on long-term data. Prior to 2005, analyses indicated stable or even increasing barbastelle population in Poland. We analysed the results of 13 winter bat counts (2005-2017) of the species from 15 of the largest hibernacula, and additional site of 47 small bunkers, in Poland. The total number of wintering individuals remained stable during the study period, because the barbastelle is not a long-distance migrant, this likely reflects the national population trend. On the basis of mean winter air temperatures we divided the country into four thermal regions. Analyses of barbastelle abundance in hibernacula in the four regions revealed a 4.8% annual mean increase in numbers in the coldest region, where mean winter temperatures were below-2˚C, annual mean declines of 3.3% and 3.1% in two warmer regions of western Poland, but no trend in the region of intermediate mean winter temperatures of between-1˚C and-2˚C. Overall, there was a significant, but weak, negative correlation between the abundance of hibernating individuals and the mean winter temperature. On the other hand, the number of individuals hibernating in small bunkers increased, even though the site was located in one of the warm regions. The results indicate a warming climate will likely reduce the use of large, well-insulated winter roosts by species that prefer colder conditions-and that this is already

The purpose of this study was to establish the impact of season on productivity, labour consumption, and working time structure during timber harvesting from young alder stands (Alnus glutinosa Gaertn.). An early thinning process was performed in summer and winter in pure alder stands (38 and 40 years old) in the Płaska Forest Division (NE Poland). The felling and processing operations were performed by experienced loggers using the cut-to-length (CTL) system, and forwarding with manual loading and unloading involved the use of a Zetor 7045 (65 HP) farming tractor and trailer. In both summer and winter, the loggers spent most of their labour time on felling trees (approx. 23%) and bucking (approx. 36%). Assistant loggers spent most of their time stacking logs (49.2% in summer and 58% in winter). The most time-consuming activities in forwarding were loading, unloading, and transportation. The average time consumption of tree felling and processing amounted to 0.36 ± 0.11 h/m3; that of forwarding was lower, at 0.24 ± 0.07 h/m3. No statistically significant differences in the labour consumption of tree felling were identified between winter and summer (p = 0.863). For forwarding, labour consumption was significantly higher in winter (0.28 h/m3) than in summer (0.19 h/m3, p = 0.001). Average productivity was 3.02 ± 1.09 m3/h for tree felling and 4.76 ± 1.80 m3/h for forwarding. The productivity of felling was similar in winter (2.83 m3/h) and in summer (3.22 m3/h). For forwarding, productivity was significantly higher in summer (5.70 m3/h) than in winter (3.81 m3/h, p < 0.01).

Wood properties have an influence on the safety around the tree itself as well as on actual possibilities of using wood. The article focuses on the wood properties of the Norway spruce (Picea abies (L.) Karst.) in reference to the time since the tree has decayed. The study was conducted among mature tree stands of spruce in Białowieża Forest, where over the last 10 years there has been a weakening of spruce tree stands due to water deficiency which has contributed to the gradation of the European spruce bark beetle (Ips typographus). The study focused on spruce wood of living and healthy specimens as well as the wood of standing trees which has decayed between one and five years before the sample was collected. The findings indicate a gradual decrease in wood properties as time passed since the physiological decay of the tree. Significant differences in the decrease of mechanical wood properties have been observed in trees which had been decayed for 3 years and they should be considered life and health hazard for people and animals.

In 2012 because of increasing transport problems the Ministers of the Environment and of the Economy announced the regulation concerning the wood density in transport (Rozporządzenie..., 2012). A series of technical roadside inspections showed that the total mass of vehicles together with their cargo substantially exceeded admissible limits. According to a study by Trzciński (2010Trzciński ( , 2011, the mass of trucks with timber ranged from approx. 40 ton to approx. 60 ton and the mean loading of a single axle vehicle ranged from 70 kN to 120 kN. The discrepancies resulted mainly from the diff erence in mass typical of individual wood species. Within the same species diff erences were also observed for individual sortments. Trzciński (2011) also stated that transported loads of large-sized pine timber of min. 21 m 3 exceed the admissible mass of the vehicle and cargo set. This would result in a considerable reduction of loads in relation to transportation vehicles' capacity. ABSTRACTThe aim of this analysis was to determine the mass of pine pulpwood, harvested from fresh-cutting trees. Analyses were made in four pine stands (aged 45, 47, 55 and 56). In each plot a total of 30 model trees were selected from among trees to be felled as a part of planned intermediate cutting. The average mass of one log of 2.5 m length ranged from 26.3 kg to 44.0 kg, at a mean of 33.9 kg. The total volume of timber harvested was 21.68 m 3 with a total mass of 21 222.4 kg. When converted to 1 m 3 the mass of timber was assessed at 979 kg. The ratio of actual density (979 kg/m 3 ) to tabular density (740 kg/m 3 ) was thus 1.3:1. As a result the actual mass of timber is approx. 30% higher than the mass that may be estimated based on the tabular density of wood assessed for the purpose of road transportation. At the stem profi le the mass of logs decreases (which is the result of stem diameter decreasing with height), while green density increases. The increase in green density of logs is probably the result of changes in porosity and moisture content of wood, as well as changes in the proportion and properties of bark.