mehrdad nikooy

Chainsaws, which are widely used in tree felling operations, create vibrations. Long-term and intense exposure to vibration may lead to the development of vascular, neurosensory, and musculoskeletal disorders in the upper limbs of chainsaw workers, known as Hand-arm vibration syndrome. This study investigates the vibration levels during tree bucking operations on poplar trees with the MPTMGS5803 chainsaw model, one of the most widely used chainsaws in forest operations in the western part of Guilan province. Simultaneous vibration measurements in three directions (x, y and z) were carried out using the SVANTEK 106A vibration meter, aiming to determine the total amount of chainsaw vibration and the daily exposure period. The results show that the highest amount of vibration was measured in the x (1.61±0.62), (2.01±0.90) direction and the lowest in the y (1.48±0.17), (0.73±0.09) direction both in the rear handle and front handle of the chainsaw. The rear handle of the chainsaw had a higher overall vibration acceleration (3.05±0.54 m/s2) compared to the front handle (1.94±0.53 m/s2). In terms of the daily exposure period, the level of vibration exposure inflicted on the chainsaw operator during a  three-hour and 70 second working period amounted to 1.19 m/s2 in the front handle and 1.87 m/s2 in the rear handle, with both values falling within the permissible vibration range.

Nowadays, chainsaws remain the primary main tool for wood harvesting in the world due to their multifunctionality and the relatively low requirements in financial investment. Another reason is that chainsaws provide high workability, enhancing efficiency and productivity, at reduced felling costs. The felling of poplar stands in the west of Guilan Province is carried out semi-mechanically using chainsaws within a clear-cutting silviculture system. Productivity and cost are two main factors that affect the selection of wood harvesting systems, whose tree felling consists an element of paramount importance, most notably its duration. The purpose of this study was to assess the productivity and cost of clear-cutting operations in a poplar plantation located in the western part of the Guilan Province, using the MASHOUF PSI 9700, a short-bladed chainsaw model with a bar length of 50 cm.

The research was conducted in the Tanyan district, which is located in the western part of Guilan province. A work team, consisting of a chainsaw operator and a helper, was used during the study. The selected work team was chosen as representative of the average skill level of the workers in the region. The chainsaw selected for this research, the MASHOUF PSI 9700 model featuring a cylinder displacement of 54 cm3 a power output of 2.2 KW, and a weight of 5.1 kg excluding equipment, had been in operation for about 2000 hours, which is the average life span of a product of this category. Over the years, the research on consumption time has focused especially on establishing the relationship between work efficiency and productivity carried out considering various equipment and wood harvesting factors. Analysis of work time consumption and productivity in chainsaw operations is an important concern of sustainable harvest management. A time study was performed to calculate the hourly productivity rate. Felling time was classified into two categories, namely effective time and delay time. Effective time consisted of (a) Moving towards the tree, (b) Felling preparation, (c) Under cut, (d) Back cut and (e) Refueling. Moreover, the delay times fell into (a) Rest time or personal time, (b) Operational delays, and (c) Technical delays. The total fixed cost was obtained considering the chainsaw purchase value, the sum of the annual investment, the depreciation, the insurance and taxes. Variable costs were also calculated considering the hourly expenditure on fuel cost, maintenance as in the cases of chain and sprocket replacement, etc. The sum total of costs included fixed, variable and labor costs. The data was initially processed using Excel 2013 software and then analyzed using the SPSS statistical software version 18 to determine the distribution and ratio of work interruption time according to the factors affecting it. Regression analysis was conducted to explore the relationship between the factors affecting the total cut-off time.

A total of 133 trees were felled amounting to a volume of 109.06 m3. The total work time consumed for felling operations was 500.21 minutes. Of the total working time, 41.42% was allocated to main work tasks. Supplementary work, such as moving between trees and driving wedges, accounted for 8.84% of felling time, while preparatory tasks, including moving between workplaces and preparation activities, constituted 15.29%. Repair time accounted for 9.60% of the total time, while delays and downtime occupied 15.74%. Additionally, 9.09% of the time was spent on non-workplace activities. The majority, 71% of the delays were linked to personal delays, of which 80.7% were related to lunchtime breaks and 19.93% to other personal delays. Operational and technical delays accounted for 10% and 19% of total delays, respectively. Increases in the diameter of the felled trees, resulted in increases to both the net felling time and the net production of the felling team. Furthermore, an increase in the diameter decreased the production cost. The results showed that the average time consumed per tree for felling were 2.73 min of effective time vs 3.75 min of gross time, and net hourly productivity amounted to 17.28 m3 per hour vs 13.44 m3 per hour found for the gross hourly productivity, and the unit cost of net production was 0.25 USD vs 0.32 USD for the gross production, respectively. The statistical analysis exhibited a highly significant correlation between work element times (measured in minutes) and various factors, including the diameter of the tree at breast height, tree volume (measured in m3), and the distance between trees (measured in m).

By developing mathematical models of working time for various chainsaw models, chainsaws, the performance of the felling teams can be increased, and a more equitable remuneration of the forest workers is made possible. The results of the present study can support decision making regarding the work rates, work schedules, and cost estimation. The models and results presented in this study can generally assist forest managers to better understand the factors affecting productivity and cost during different work elements with the aim to reorganize and plan forest work to meet economic concerns.

Several methods have been proposed to evaluate soil quality in line with its management and provide suitable management solutions. Visual assessment method of soil disturbance provides a quick and effective tool for cheap evaluation of the quality of the soil in the field. The method of visual evaluation of soil degradation provides a quick and effective tool for cheap evaluation of soil quality in the field. The aim of this study was to visually assessment of soil disturbance due to forest operation by short wood and full tree methods in western plantations of Guilan province. For this purpose, 625 plots were measured in each method based on visual soil assessment method. The results showed that the studied operation methods destroyed different proportions of field areas so that 79.36 and 69.92% of the total area were destroyed in the short wood and full tree methods, respectively. Logging residuals in short wood method was more than in full tree method. The results showed that soil compaction in the short wood method (18.72%) was higher than in full tree method (14.08%). Logging residuals, shallow disturbance and soil compaction were the most common types of soil disturbance cause by logging methods, therefore the highest amount of disturbance in both methods was related to the logging residuals class. The results of Mann-Whitney U test showed that there was a significant difference between the two forest logging methods. In general, the results showed that the type of timber removal method in logging operations and skidding has a significant effect on forest soil disturbance.

In the current study, the quantity, quality, and bole form of trees were investigated in three parcels of selectively logged, protected, and recreational areas in the mixed beech (Fagus orientalis) stands in Nav-e Asalem forests. The quality and bole form of trees were measured and evaluated through systematic plot sampling. The results of the research showed that the abundance of live trees in the selectively logged parcel (268 trees ha-1) and recreational parcel (210 trees ha-1) was lower than that in the protected parcel (389 trees ha-1). The abundance of beech, maple (Acer cappadocicum), and alder (Alnus glutinosa) species in the selectively logged parcel, and the abundance of beech and alder species in the recreational parcel were significantly higher than their abundances in the protected parcel. The abundance of snags in the protected, selectively logged, and recreational parcels was 18, 9, and 8.4 stems ha-1, respectively. The average abundance of stem deformity in the protected, selectively logged, and recreational parcels was 18.3, 9.4, and 8.4 stems ha-1, respectively. Logging operations, although increased the frequency of leaning and bending stems, decreased the frequency of conical and decaying stems. In general, the abundance of high-quality trees and boles in the selectively logged and recreational parcels was higher than in the protected parcel. Regular and long-term monitoring of the quantity, quality, and form of tree trunks may be a good approach to align ecological and economic goals in forest management.

Despite progress in full mechanization, motor-manual logging technologies still dominate in many countries, including in North plantation forest of Iran. Motor-manual timber harvesting is considered to be one of the most dangerous working operations. The physical demands of work are still one of the crucial workload factors in most jobs in the forestry sector, especially those connected to manual loading. The aim of the study was to investigate the physiological workload of a worker during manual loading in a poplar plantation stand in the north of Iran. Physiological responses were assessed on a sample of 12 workers manual loading during a normal working shift. Polar heart rate monitors were fitted over a period of a week in order to record ‘working’ heart rates. The collected data were used for the calculation of heart rate indices that determine the strain of the subjects. The average mean heart rates during work time, rest time, and maximum heart rate were 132.42, 79.42, and 175.16 bpm respectively. The results showed that the mean level of physical workload was 55 which correspond to very heavy work. The study results also showed that age and body mass index of workers is significantly effective on HRw and weight of workers on HRw and HRmax, respectively. The results revealed high physiological demands of manual loading. Increasing the mechanization level with investment in modern equipment may be proving beneficial in enhancing workers health and safety.

In this study, the physical, chemical and biological characteristics of compacted soil due to tracked skidding (LTT-100A) after 35 years (from 1986 to 2021) of clear cutting operation were investigated in an even aged mixed deciduous stand in Masal forests, Guilan province, northern Iran. Three levels of machine traffic intensity (TI) (low, LT; medium, MT; and high, HT), two levels of skid trail slope (SC) (Gentle, <10%, GS; and steep, ≥10%, SS), two sample locations(SL) (Between track, BT; and On tracks, OT), and two soil depths (SD) (0-5 cm, and 5-10 cm) were considered as independent variables affecting the process of soil profile recovery. The values measured from the abandoned skid trails were compared with those of undisturbed areas to estimate the soil profile recovery rates. Results showed that TI had significant effects on all soil physicochemical (except for soil moisture) and biological properties (i.e., leaf litter, above-and below-ground biomass); all physicochemical and biological properties (except for soil moisture and leaf litter) were affected by SC; the effect of SL on soil texture, density and moisture was significant; and soil texture and density were the only characteristics affected by SD. The values of soil bulk density and penetration resistance on the skid trails were 35% and 49% higher than those of the control area, respectively, while total porosity value was 17.5% lower than that of the control area. Furthermore, soil organic carbon on the skid trails was 20% less than that of the control area. The amount of soil biomass on the skid trails was not recovered after 35 years, so the above and below ground biomass on skid trails were 42% and 46% less than the control area, respectively. The value of leaf litter on the skid trails was 31% less than that of the control area. Overall, the results of this research revealed that the soil of the studied forest is sensitive to the activity of timber harvesting machines. Thus, sustainable forest management needs to reduce the impact of logging within the context of best management practices (BMPs).

Manual loading of logs consists of dangerous, heavy and tedious work tasks. The involved workers have to lift and carry heavy loads during the day, which has been associated with physical fatigue, muscle pain, as well as a high risk of work accidents. The objectives of this research were a) to analyze log loading worker and b) calculate the Postural Risk Index (PRI) during manual loading activities in a poplar plantation by means of the ErgoFellow 3.0 software and the Ovako Working Posture Analyzing System (OWAS) ergonomic method. Field measurements and data collection were carried out in the summer of 2020 and consisted of video recordings during the effective work time. The snapshot method was used in the recorded material and a total of 34 mixed body postures were identified based on the effect of body posture on the musculoskeletal system. Study of the frequency and percentage of mixed body posture revealed that 7 code values are in action level 1and do not need to be corrected while in 6 code values, corrective action required in the near future, 11 code values require faster correction, and 10 code values require immediate correction. The PRI of the loading operations was 276, suggesting a strong need for ergonomic improvements. Health hazards as a result of manual loading of logs are, largely, unknown to the workforce in rural areas despite their connection to physical and mental exhaustion, and can expose workers to musculoskeletal disorders resulting in reduction of their work capacity..

Undoubtedly, log smuggling is one of the most significant factors in quantitative and qualitative reduction of the Caspian forests in north of Iran, while it has received less attention in forest studies. This study was conducted to identify the causes of log smuggling in Guilan Province, Iran. A team of 24 experts from Forest Protection Department, Natural Resources and Watershed Management Organization, Guilan Province was selected, and the study was carried out in three phases by questionnaire and Delphi method. According to the frequency of responses to the first open-ended question in the first stage of Delphi method, number of 24 various specialists’ ideas were identified as the causes of log smuggling. Greed of profiteers, unemployment and the need for income especially among young people, lack of planning in each forest area, poverty in forest communities, easy access to forest areas through forest roads, and closure of forestry plans had the highest frequency among responses. Based on the results from phase two of Delphi method, unemployment and the need for income especially among young people was the notable cause of log smuggling. Systematic corruption, greed of profiteers, poverty in forest communities, failure to deal effectively with log smuggling agents, buying and selling smuggled wood without any trouble are ranked second to sixth, respectively. The Kendall's W test showed no concordance between experts on the questions in relation to the comparison between the ranks among the variables. The results of the tests also showed that the “unemployment and the need for income especially among young people” factor was the first rank, while the “timber industry dependency on certain types of wood” was the last one. The summary of interviewee's opinions after the Kendall's W test illustrated that the most principle log smuggling causes are as follows: unemployment and the need for income especially among young people (94%), systematic corruption (89%), greed of profiteers (86%), and poverty in forest communities (84%), and failure to deal effectively with log smuggling agents (82%). By identifying the factors affecting log smuggling, the necessity of using a strategy to deal with these factors in Guilan Province is felt more than ever.

One of the causes of instability of sloping hillsides is the construction of forest roads, which leads to soil erosion and its effects. The purpose of this study was to study the effects of litter cover and residuals on runoff and sediment in the cut slope and fill slope of forest roads in the forests of Guilan province. For this purpose, four cut slopes and fill slope were selected and in each of them, four plots (2 m2) with four litter cover and residuals including without cover, 30%, 60% and 90% and with a fixed slope of 30% was measured. Samples were measured after each rainfall with an approximate intensity of 80 mm/h. The results showed that the mean of runoff in the cut slope were 759.3, 748.6, 372.6 and 196 ml/m2, in the fill slope were 216.6, 156.6, 77.1 and 69.5 ml/m2, respectively. Mean of sediment in the cut slope were 1.08, 0.96, 0.13 and 0.07 g/l, in the fill slope were 1.51, 1.06, 0.27 and 0.08 g/l, respectively. The results of analysis of variance showed that there was a significant difference between the amount of runoff and sediment created in the litter cover and residuals classes (P<0.05). The mean of runoff produced in the cut slope was significantly (P<0.05) higher than their mean in the fill slope in all cover percentages. Results of the study showed that litter cover and residuals had a significant effect on reducing runoff and sediment in forests roads.

It is necessary to find solutions for soil recovery of skid trail. Water-bar construction is one of the ‎best management practices to improve the compaction and prevent the erosion of skid trail soil. ‎Recovery of soil physical properties 11 years after water-bar construction on skid trail was ‎investigated on 40 square meter sample plots in two slope (0-10% and 10-20%) and three traffic ‎classes (Low, Medium, High) in the forests of Nav district in the west of Guilan province. The ‎studied variables included soil bulk density, total porosity, penetration resistance and rutting depth. ‎Soil bulk density, penetration, and rutting depth were measured by steel cylinder, pocket ‎penetrometer, and a 5-m leveling rod. The parameters in each treatment were studied in three ‎replications. The effect of slope and traffic variation on soil physical properties was performed on 72 ‎sample plots. The results showed that the effect of slope, traffic and their interaction were ‎significant on soil bulk density, total porosity, penetration resistance, and depth of rutting. The ‎value of soil bulk density, total porosity, and penetration resistance in LSLT (Low Slope-Low ‎Traffic) class was recovered, and there was no significant difference between this class and the ‎control area. The results of the study showed a positive effect of water-bar construction on the ‎recovery of soil properties in skid trail with low slope and low traffic.

Protective measures are needed to reduce the negative impacts of soil compaction. Water diversions are one of the management tools to reduce the negative impacts of ground skidding and helping soil recovery. In this research, the effects of constructed water bar were studied on the process of soil physical properties recovery in skid trail in west of Guilan. Seven years after logging completion and conservation of skid trail by constructed water bar, changes in soil physical properties were evaluated in two slope classes and three traffic classes in 40 m2 sample plots at wheel tracks and between them. Control samples were selected within 30 m from the edge of the skid trail. Soil samples were collected using a cylinder to a depth of 10 cm. Soil penetration resistance and rut depth were measured by analog hand-held soil penetrometer and rut 5 meter leveling rod, respectively. Influence of slope and traffic changes on soil physical properties was investigated in two treatments, three replications, and 72 samples. The results showed that the slope of the skid trail, traffic intensity and their interaction have significant effective on bulk density, total porosity, penetration resistance and rut depth. Mean bulk density, total porosity and penetration resistance in slope below 10% and low traffic treatment were not significantly different from control area. Overall, the results of study indicated that after log skidding, water bar construction had positive effects on soil physical properties of low slope and traffic trails.

The purpose of this study was to evaluate the effect of road distance and age on roadside vegetation cover on  Nav district forest roads in the west of Guilan province.Therfore required data in 240 Systematic random plots on linear transect in two road age classes were collected. Percentages of vegetation were calculated using Brown Blanket combination scales. Then, the values ​​of richness, evenness, Shannon-Wiener, and Simpson indices were calculated for each age class of road. Relative importance index was used to determine the distribution of species abundance. The results showed that the relative importance and presence of dominant tree species in the newly constructed roads were higher than the old ones. In both age groups, the relative importance of beech (Fagus orientalis), hornbeam (Carpinus betulus) and alder (Alnus subcordata) saplings was higher than other species. Also, the relative importance of tree species decreased with increasing distance from forest road. Also at different distances of the road, beech and maple regeneration were the most frequent. The highest values of diversity and richness were observed at 0-30 m distance from the road and its value was significantly different from other distances.

Indicator species are one of the important components in vegetation classification, and studying and determining them on the roadside of old roads is very important for maintaining the habitat for rare and endangered plant species. Awareness of the road age can be effective in preserving and developing the plant communities, as the road effect can be helpful in optimal management of vegetation when constructing or maintaining new roads. The purpose of this study was ecological classification as well as identification of indicator species in roadside of forest roads with different ages in Nav-e-Asalem area, west of Guilan province.

Data were collected by random sampling, as in the seven forest areas of Nav-e-Aslam, Guilan, a number of 28 transects (150 m in length) perpendicular to the road from roadside to the inside of the forest using line transect method, linear transect method was used and 28 transects (150 m in length) perpendicular to the road were taken. The distance between the transects was 100 m, Five sample plots (30 × 5 m) were taken for sampling trees and shrubs with a distance of 30 m from each other. In 4 m2 sample plots herbaceous species were identified using vegetation flora and vegetation percentage was recorded in different strata (tree, shrubs and herbaceous) using Braun-Blanquet scale. Also, indicator species analysis was performed using ecological group sample in PC-ORD for Win. Ver 5 software.

The results of indicator species analysis showed that 146 species were found in the roadside of roads with several years’ age. The presence of tree and regeneration species was higher on old roads compared to new ones. In this research, newly constructed roads (10 years) occurred in two groups of second and fourth ecological species, roads with medium ages (10-20 years) in the third ecological group and older roads (>20 years) in the first ecological species group. By using two-way indicator species analysis (TWINSPAN), vegetation cover was classified into two groups: Viola alba Besser, Carpinus betulus L. and Brachypodium sylvaticum, Carex divulsa Stokes. In this research, the presence of Alnus subcordata CAMey and Acer velutinum Boiss species was higher in the sample plots near the road compared to inside forest. The diversity of these tree species and their relative frequency decreased by increasing the distance from the roadside and moving to inside forest. In this research, Carex divulsa Stokes was identified as a rare species and Fagus orientalis Lipsky as a species with high frequency.

The results of this research emphasize the importance of road age not only in determining the ecological species group, but also in identifying the indicator species in the area as well as in improving the classification results of tree, herbaceous and regeneration species in roadside area. Determination of the indicator species is effective not only in determining the extent of the ecological groups classified on the roadside, but also in improving the classification results of plant groups as well as identifying the factors affecting ecological groups seems to be useful for proper management and sustainable exploitation of forest ecosystems.

This study explored the effect of tree shadings on a number of destruction indices for forest road pavement. Therefore, selective sampling was conducted within three various elevation classes in the Chafroud watershed in the west of the Guilan Province. Pavement distress indices of improper cross section, inadequate roadside drainage, corrugations, potholes and ruts dimensions, and loose aggregate were measured. By surveying the road, the plots with a canopy cover > 50 % and a paired plot beside each plot on the road were selected for measurements. Based on mentioned indexes, 12 distress variables were measured and compared among plots under the shadow of the trees and opened plots in three classes of traffic level. Results of analyses in low elevations showed that distresses of an improper cross section, number and area of potholes of plots with canopy cover > 50% were significantly more than plots with canopy cover < 50 % (p < 0.05). In middle elevations, no differences were observed between the plots, while in high elevation (i.e. with low traffic) the distresses of improper cross-section, area of ruts, and loosing aggregate plots with canopy cover > 50% were significantly higher than plots with canopy cover < 50 % (p < 0.05). No difference was observed in other variables. The results of this study showed significant differences in about half of the studied indices between shaded and non-shaded regions, yet the change in traffic variable did not determine any decreasing or increasing trend of shadow effect on road pavement quality.

Today, skeletal musculoskeletal disorders are one of the most important occupational health issues and have a high prevalence in almost all occupations, and preventing it involves evaluating and modifying working conditions. This study aims at assessing the risk factors of musculoskeletal disorders of work by QEC in forestry workers of two regions of Guilan and Mazandaran forests. In this study, statistical population included 51 workers in three jobs of felling and bucking, skidder driver, and manual loading worker were studied by census method. The Nordic questionnaire and QEC method were used for determining the prevalence of musculoskeletal symptoms and assessing the risk of these disorders, respectively. The results showed that the highest prevalence of musculoskeletal disorders was in the waist, neck and back segments, respectively. The significant relationship between weight, body mass index, work experience and smoking with musculoskeletal disorders was observed. Results of QEC evaluation showed that the 72.6 percent of worker are in risk level of 4, while these values for risk level 1, 2, and 3 were 7.8, 9.8, and 9.8, respectively. In vibration exposure, speed of operation and stress about 64.7, 62.7, and 70.6 percent of worker were in high and very high levels. The results indicate a high prevalence of disorder among workers. The main ergonomic problems in study area include inappropriate physical condition, bending and twisting of the waist, lifting and carrying heavy loads, vibration, speed during work and stress.

Chainsaw is the main dangerous equipment in forest work which has great potential damage to felling crew. Management of the risks arising from working with a chainsaw depends on the assessment of its risks. There is still no suitable method for evaluating the risk of work with this device. Generally, the risks of working with chainsaw are presented without rating. This study was designed to rank the dangers of working with this device. For investigation of dangers related to chainsaw during tree felling Job safety analysis was used. During these phase, comment of chainsaw men, felling operation supervisors, harvesting experts, and Work safety specialists working in forestry plan in Caspian forest were used. Then, the risk assessment criteria were investigated by Delphi method with help of felling workers, forest watershed managers, forestry specialist, and university professors. Results were Conclusion by forest safety experts. Finally, the risk ranking was done using the Fuzzy Topsis method. Risk assessment criteria were obtained using the Delphi method. Ranking of hazards with Fuzzy Topsis was determined. The results of this study showed that the dangerous trees, butt log and chainsaw kickback are the most important risks of chainsaw operation. This study enhanced the ability of risk detection of felling operation with chainsaw and correct risk assessment criteria identification with ranking of felling hazards. The final analysis resulted in rating the dangers of working with this device that it can reduce the incidents caused by working with this device by compiling the appropriate safety instructions.

Forest roads can create small- scale climate change. These changes can vary with the road age and topographic conditions. This study aimed to identify ecological species group as well as study the relationship between vegetation and environmental factors based on the road age. The study was carried out in three-districts of Nav- Asalem in Watershed 7 of forests of North of Iran. Therefore, 140 sample plats (rectangular in shape and150 m2 in area) with different ages and different topographic conditions were taken. Information related to tree and shrub cover, regeneration and weed cover along with slope (%) and slope aspect of sample plots, road age and elevation, as well as the amount of light receiving to forest floor, temperature and humidity at the center of the sample plots were recorded. The ecological group distribution pattern was evaluated using non-limited ordination method and classification of ecological groups was performed using Two Way Indicator Species Analysis (TWINSPAN) and CCA gradient analysis. Data analysis was carried out using Excel and PC-ORD software. The results of the analysis of indicator species showed that of 72 plant species, only 52 species were determined as indicator species that were defined as indicator species of beech communities on roadside. In this research, newly constructed roads (with age below 10 years) occurred in second and fourth ecological species groups, roads with moderate ages (10-20 years in age) in the third ecological group and older roads (with age more than 20 years) in the first ecological species group. The results of MRPP analysis (multi-response permutation procedure) showed that the ecological groups are characterized by higher distance from each other. Among the ecological groups, the abundance and presence or absence of species with environmental variables were not the same in all sample plots. The final results showed that the road age not only affects the ecological species group but it also serves as a useful factor in determining the indicator species and improving the results of the ordination of the ecological species group on the roads with age more than several years.

The objectives of study were to compare different types of wood loss including breakage, split, slab, and high stump and also to investigate cut components such as, height and depth of undercut and back cut, notch, and width of hinge wood between the two groups of workers. Parcels no. 138 and 139 in Asalem Nav series 1 were chosen as the study area. 150 felled trees by workers paid by piece and day work method were selected randomly. The mean stump loss between the two groups was compared by Independent- Sample T- test and the comparison between the size of each components of felling and the standard felling was made by Paired Sample T-test. There was a significant difference between felling values in different groups compared with standard values except the depth of back cut in the second group (33.41 cm) and the width of hinge wood in the first group (6.78 cm). The average high stump loss for the four groups was 0.035, 0.0355, 0.0498, and 0.0438 m3, respectively. The average loss per felled tree among the four groups was 0.2915, 0.2286, 0.3775 and 0.4637 m3, respectively. There was a significant difference between mean value losses of wood in the four groups; the day work paid group had fewer losses compared the piece work paid group. The largest volume of loss in all groups belonged to breakage damage. Regarding the price of different products fabricated from the wood cut, results showed that the greatest decrease in price belonged to the groups paid by piece work contract.

Logging secondary damages on remained trees are one of the challenges in management of uneven-aged stands which have been less studied in the northern forests of Iran. In this research decay frequency and volume of bole trees after 15 years from wound occurrence were studied through systematic-random sample plots with 1000m2 plots in the Nav-e Asalem forests, Iran. The conditions of trees were registered in two types: safe and wounded, the wounds were registered in two types: open and decayed; and volume of decayed bole was calculated by Smalian formula. Results indicated that 16.1% of wounds were led to bole decay. Decay frequency and volume were estimated to 5.5 trees ha-1 and 1.7 m3ha-1, respectively, that includes 1.96% of total trees and 0.72% of total stand volume. Coefficients of decay frequency and volume on the base of frequency of logging primary damage (12.2%) were calculated 0.16 and 0.06, respectively. Decay frequency of wounded trees bole were related with tree species, wound location, diameter at breast height (DBH), situation of wounded tree in stand, and slope aspect. Decay frequency and volume in the trees of lime and oak were more than other tree species. Decay frequency was increased by decreasing wounds distance from ground. Decay frequency and volume in the high diameter wounded trees were more than low diameter wounded trees. The wounds on the trees in edge of skid trails were more decayed than the other wounds. Decay frequency of wounded trees on the northern aspect slopes were more than the southern aspect slopes. In general, minimizing of primary logging damages, reducing harvest intensity, increasing logging period, and harvesting bole-decayed trees in the next logging periods are suggested.

Single tree selection method needs to an accurate estimation of logging damage to residual stand for ecological and sustainable forest management. In this research accuracy and required time for estimation of frequency of damaged trees due to logging operation were assessed through plot and line samplings in a harvest unit of 30 ha area in Asalem Nav forest, northern Iran. In both samplings with same sampling intensity (10% of total area in plot sampling and equal total line lengths in line sampling) five samples size (plot and line sample numbers) were applied with different grid dimensions of systematic sampling method. The results showed that the sample size had significant effect (P 0.618) with actual damage (100% inventory). Adequate grid dimensions were determined 100 m × 100 m with plot areas of each 0.1 ha for plot sampling and 77.5 m × 77.5 m with sample line lengths of each 60 m for line sampling. Required time for line samplings were about 90% lower than plot samplings. These results indicate the line sampling can be used for accurate and rapid estimation of frequency of damaged trees due to selection cutting and ground skidding.

One of problems in managing of uneven-age forests is logging damages to residual trees and reducing stand quality and quantity in years after logging operation. In this research, trend of bole decay and economic loses by it, following logging damages, were analyzed at a 10 year period in a mixed beech forest in Guilan province. Volume of decayed section on trees bole was measured by Smalian formula, and volume of standing trees bole was estimated by local tree volume tables via plots of 0.1 ha area and systematic sampling design at the start and end of period. Results showed that volume of decayed bole were increased from 0.48 m3/ha at the start of period to 1.71 m3/ha at the end of period (P

Protection of forest soil is one of key factors in having sustainable productive forests. In this research extent and intensity of soil disturbance due to extraction of logs of felled trees (20.5 m3/ha) were studied in Nav-e Asalem forest in Gilan province. After finishing the skidder logging operations, soil disturbance were studied by point-transect sampling method and visual assessing. Results indicated that about 19 ± 6.2 percent of surface soils were disturbed due to winching of logs that 11.3 percent of them disturbed with shallow intensity and 7.7 percent disturbed with deep intensity. The extent and intensity of soil disturbance were decreased by increasing distance from skid trail. The extent and intensity of soil disturbance were increased by increasing of ground slope. Soil bulk density in the shallow disturbed soils (1.29 g/cm3) and deep disturbed soils (1.44 g/cm3) were increased 2.4 and 14.3 percent, respectively, than control soils. Soil bulk density of disturbed areas were increased by increasing ground slope, so in slopes greater than 50 percent soil bulk density was increased 20.8 percent more than control soils. Including ways to reducing soil disturbance during skidder logging in the study area are reduction in harvest intensity, implementation of felling direction and skidder logging limitation to slopes less than 50 percent.

Logging is one of the critical operation in forest management that causes damage to remaining trees in forest. Reducing frequency and intensity of damages during logging operation is one of the main goals in section cutting forests. The aim of this study was analysis of effective factors on damage during logging of each tree in Nav forests.
From total of selected trees to cut in the two parcels of the Nav forests, the number of 83 trees (22.7%) were randomly selected and damages to remaining trees were individual-level analyzed during felling, winching and skidding operation.
Results indicated an average 13.3 damaged residual trees per each harvested tree, which 3 trees were damaged at felling stage, 8.9 trees were damaged at winching stage, and 1.4 trees were damaged at skidding stage. Diameter at breast height (DBH) of felled trees were from 25 to 107 with average 68.4 cm, and their heights were from 12.5 to 27.3 m with average 21 m, and damaged trees were increased by increasing of DBH and height of harvested trees. Winching distance were from 3 to 47 m with average 24.5 m, and winching angle were 0 to 47 degree with average 19.1 degree, and damaged trees increased by increasing the distance and angle of winching. Damaged trees were increased by increasing of number of skidd-trail curves and by decreasing of skid-trail radius. Damaged trees due to felling of trees on suitable directions, and winching of the on suitable routes were lower 42.4 and 17.1 percent than unsuitable directions and routes, respectively. The DBH of wounded and destroyed trees at felling stage (63.5 and 34.6 cm, respectively) were more than their averages at winching and skidding stages. Average size of bole wounds was 327.1 cm2, average depth of bole wound was 20.1 mm, and average height of bole wounds from ground level was 0.86 m. The averages of the bole-wound sizes and the bole-wound height from ground level were higher at felling stage, the average bole-wound depths at the winching stage were higher than other stages.
The results reveled that appropriate management of selection cutting forests need to develop of sciences and techniques of logging operation. Implementation of tree directional felling, and limiting of winching operation to areas without standing trees, regeneration and ground slopes less than 50 percent are necessary for reducing logging damages to residual trees in these forests.

Directional felling of trees plays a key role in reducing of damages to forest residual trees and can also facilitate skidding. The aim of this study was presents a practical linear model for estimation of tree falling direction error in an uneven-aged mixed stand in northern forests of Iran. To conduct the study a number of 95 trees of four species Fagus Orientalis Lipsky, Carpinus Betulus L., Alnus Subcordata C.A. May and Acer Platanoides were randomly selected,and assumed felling direction were marked on the trunk of these trees. The trees felled by experienced chainsaw operators, and the differences between the assumed and actual direction were measured as the felling error. The results showed that among the 12 effective factors, the elements of foot slope, diameter at the breast height (DBH), horizontal and vertical angles and area of the backcut surface (HABS, VABS, BA),vertical angle and area of undercut surface (VAUS, UA) significantly correlated with the felling error, and the determination coefficient (R2) of presented linear model was 52.0 % (P