meghdad jourgholami

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.

The duration of vegetation restoration in the skid trails after logging operations is crucial and fundamental for preserving forests. The purpose of this research is to evaluate the long-term vegetation restoration of the skid trails in Kheyrud forest after logging operations. Therefore, 54 sample plots (1×1 m) were randomly positioned. This included 27 plots on the skid trails with ages of 5, 10, and 15 years at three traffic intensities (low, medium, and high). Additionally, 27 sample plots served as controls with a distance of 10 m from the skid trails parallel to these trails. All the plants in the plots were identified, their abundance was counted, and their species and families were identified. The results of the current research showed that among the three investigated treatments, traffic intensity alone had a significant effect on the recovery of vegetation along the skid trails. However, the age after harvesting and the interaction of traffic intensity and age after harvesting did not have a significant effect. The results also showed that traffic intensity significantly affected the abundance of species. Furthermore, in all three factors (traffic intensity, age after harvesting, and the interaction of traffic intensity × age after harvesting), tree species were more affected by soil changes compared to herbaceous species. Therefore, traffic intensity can significantly affect the variety of species and number of plants in the skid trails, with a greater effect on tree species than herbaceous species.

This study was conducted to investigate the effect of degradation due to traditional forest exploitation on runoff and sediment following the change of some soil characteristics in the Zagros vegetation area in Manesht and Qalarang protected areas in the north of Ilam. Based on the objectives of the study, the treatments of degraded forest, intact forest (control) and agricultural lands in the region were considered in three slopes (15, 25 and 35%) and each in three replications. In this study, runoff and sediment due to rainfall were considered. Analysis of variance test was used to investigate the effect of vegetation cover on runoff and sediment, Duncan's test was used to compare means, and Pearson's correlation method was used to determine the significance and extent of each variable measured in the soil on runoff and sediment. The results showed that with increasing the slope, the amount of water infiltration in the soil decreases and as a result, more runoff and sediment is produced. The results showed that the amount of runoff, sediment and runoff coefficient in degraded forest lands is higher than the treatment of intact forest (control) and agricultural lands. In degraded forest lands, the amount of runoff is 5.43 mm and sediment is 0.3671 tons per hectare and in untouched forest lands (control), the amount of runoff is 0.33 mm and sediment is 0.0019 tons per hectare, respectively, and in agricultural lands, the amount of runoff, and sediment were calculated as 22. 0.00 mm and 0.004 t / ha, respectively. The results of correlation coefficient showed that the parameters of acidity, clay percentage, silt percentage had a positive correlation and sand percentage had a negative correlation with runoff and acidity parameters, silt percentage had a positive correlation and sand percentage had a negative correlation with sediment content. According to the results of this study, it can be concluded that eliminating or changing the use of vegetation, especially forest cover reduces the amount of soil permeability and thus increases the amount of soil runoff and sediment. Therefore, by preserving, rehabilitating and developing forest trees and shrubs, as well as preventing the change of use of these lands to agriculture, especially in sloping forest lands, runoff and sediment production can be prevented.

Forests and the environment play important role in providing income, food, energy, medicines and genetic resources, and a variety of essential materials for the well-being and living conditions of the people and the preservation of culture. In this research, an attempt has been made to elucidate the functions of forests and the environment in Iran and their links to food security and nutrition by reviewing documents and referring to statistics and data of national and international organizations. Direct forest and environment ecosystem services include the sale of wood products, fuel wood or firewood and by-products or   non-wood products. In this study, the statistics related to Iran's forests were briefly pointed out, which include revenues from the harvesting of wood and non-wood products, energy obtained from firewood in cooking for optimal use of food and the direct role of some  non-wood products in direct provision in the food system. Indirect forest and environment ecosystem services play a major role in the “availability” and “stability” components of food systems, including biodiversity, climate change, water regulation and quality, and soil and nutrient cycling conservation. Biodiversity makes production and livelihood systems more resilient to shock and stress including climate change. Climate change and climate diversity threaten the provision of a wide range of important products (timber and         non-timber) and forest environmental services. In this study, while examining the relationship between global environmental changes and food security, the strategies for overcoming the current situation were enumerated.

Various engineering measures, such as mulching, have been applied to skid trails to suppress the negative effects of surface runoff and flood hazards. However, study on the effectiveness of such treatments to restore soil properties is scarce. In this study, the effect of organic mulches including leaf litter, rice straw and sawdust on the recovery of physical properties of compacted soil of skid trails (i.e., soil bulk density, porosity, resistance to penetration and soil texture) was evaluated and tested two years after skidding operations compared to untreated trails and undisturbed (control) area. The results showed that the treatment of leaf litter mulch, rice straw and sawdust had a significant effect on the recovery of soil bulk density, porosity and soil penetration resistance, but had no significant effect on soil texture. The results showed that litter mulch has the greatest effect on the recovery of soil physical characteristics compared to straw and sawdust mulch. However, for two years, the soil texture was not affected by the type and amount of mulch. Also, in the surface depth, the effects of mulch are more significant. We can conclude that the applying different organic mulches increased levels of each mulch moderately ameliorated soil physical properties, after mechanized operations over a two-year period, compared to the untreated treatment; however, the values of soil properties were still lower than those in the undisturbed (control) area, indicating that two years is not long enough to restore the soil properties to pre-harvest levels in the study area.

In order to investigate the factors affecting damage caused by early snow in the compartment no. 10 in Patom district of Kheyrud forest research station, the sampling was conducted on a random grid (100 × 100 m) with 46 m 1000 circular sample plots. In each plot, effective factors including slope gradient of the plot, aspect, altitude (elevation), soil depth, diameter at breast height, and height of all tree species greater than 7.5 cm were recorded. Damages to trees were classified into four types including uprooting (tree throw), trunk fracture, crown fracture, and bending. The results showed that 28.1% of the trees were damaged, with damage of 3, 4, 10 and 11% for each type including uprooting (tree throw), trunk fracture, crown fracture, and bending, respectively. The results showed that there was a significant difference between the types of tree damage and some factors including aspect, slope, elevation, and soil depth. The highest percentage of tree damage occurred in the northern aspect, slope less than 15%, altitude of 330-380 m, and shallow soils depth, and the lowest occurred in the southern aspect. The damage on the eastern and western slopes was approximately similar. The highest and the lowest percentages of damage were related to alder and maple tree species, respectively. Thinning treatments affected the horizontal and vertical structure of the stands by reducing the slenderness coefficient of trees, which has a key role in reducing the severity of snow damage on trees, and improves tree and stand stability.

Forest machinery traffic on forests causes significant changes in increasing the bulk density, reducing porosity, ventilation and reducing water infiltration rate which resulted in an increasing surface runoff. According to the results of previous studies on the effect of mulch on reducing runoff in laboratory conditions, The aim of the present study was to determine and compare the amount of runoff produced in untreated skid trail, undisturbed forest (control area), and the skid trail plots covered by sawdust, under natural conditions in Namkhaneh District, Kheyrud Forest to find useful strategies to reduce the effects of forest utilization in order to maintain the function of forest water protection and reduce runoff. In this study, the runoff plots (6 m2) were triplicate established and runoff collected by pipes in the outlet plots were measured based on natural rainfall conditions. The results revealed that applying sawdust mulch to the skid trail decreased runoff compared to the untreated skid trail, and the runoff amount in undisturbed forest, untreated skid trail and sawdust mulch treatments were 0.40, 1.44 and 0.71 mm, respectively. The highest and the lowest amount of runoff were found for untreated skid trail and undisturbed forest treatments, respectively. Also, by application of sawdust mulch, the amount of runoff produced reduced by 48.4%, while the amount of runoff before the use of mulch in skid trail was 72.2% higher than the intact forest. Also, the runoff produced in skid trail control treatment was 51.1% higher compared to sawdust treatment.

Land use changes can significantly affect the hydrology of a forest watershed. Ground cover is important to protect the soil against erosion. Timber harvesting has been changed the canopy cover and forest soil was exposed to the wind and water. Soil compaction and removing the forest floor in the skid trails was reduced the capacity of water absorption in mineral soils and thus reduced water infiltration, increased runoff, which caused to soil erosion. In order to measure the rate of sediments in two slopes and to study the effect of skid trails on the amount of sediments, the plot-level study was carried out in the Gorazbon district in Kheyrud forest in the control area and skid trail after skidding operations in the sample plot. The results showed that the most sediment value was 1.938 g. liter-1 in the skid trail with a 20-40 percent slope in the autumn and the lowest deposition was 0.103 g. liter-1 in the control area with a slope of 20-40 percent in the autumn. Type of Coverage (skid trail and control area), the season and the interactions between the cover and the season statistically have significant effect on the sediment yield, but the slope and the interactions between the slope and cover, as well as the interactions between the slope and season have no statistically significant effect on the sediment yield. Duncan’s test showed that there was a yield statistically significant difference between sediment yeild in different seasons and the autumn had the highest sediment

In close to nature silviculture system knowing the amount of forest stocking is critical issue to management, optimal and sustainable utilization of forest and its production. This research was done in compartments of 305, 306, and 309 with total area of 88 ha. Volume increment calculated using direct method by full calipering inventory. Current stocking volumes (2014) were acquired 431.6, 457.6, 455.7 m3ha-1 for 305, 306 and 309, respectively. The volume growth results showed that the gross annual volume increments were 3.3, 4.6, and 3.8 m3ha-1 for 305, 306 and 309, respectively. Furthermore, the percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 2.54, 2.03 and 0.96 in compartment 305 respectively. Moreover, the percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 2.58, 3.1 and 1.55 in compartment 306, respectively. The percentage of the annual volume growth rate compared to beginning of period (2004) for small, intermediate and large diameter trees were 7.08, 3 and 1 in compartment 309 respectively. The maximum amount of volume growth was occurred in 35 and 40 cm diameter classes while the growth rate was gradually reduced diameter classes greater than 75 cm.