Logging OPERATIONs is an engineering system with the aim of maximizing efficiency and minimizing negative effects. This study was carried out in two compartments including 220 and 225 in Namkhaneh district of Kheiroudkenar watershed. In this study, damages resulted from SKIDDING OPERATION by Timber jack 450C were evaluated. The results of this study showed that in two compartments 220 and 225, 80.6% and 72.7% of scars resulted from SKIDDING OPERATIONs was happened in low parts of the tree (root and stump area) and more than 40% of scars are with the area of lower than 200cm2, but 57% of scars are accompanied with cambium damage. The results of study showed that with regarding to lower logging intensity in compartment 225 compared to compartment 220, the average size of scars in compartment 225 (10.43cm) is more than compartment 220 (9.06cm) that this important note is referred to more skid-trail turns in compartment 225 compared to compartment 220 (around 2 times more). Also, the results of analysis of variance showed that the wound-stem ratio is significant difference between two compartments in 1% level (F=9.01, P=0.003, df=1). Generally, concluded that increasing number of turns in skid-trails have more degradation effects in comparison with harvesting intensity on edge trees.

The development and deployment of harvesting systems aims to provide physically feasible, environmentally sound and economic solutions. The data of residual stand damage was collected from a mixed broadleaved stand in Kheyrud forest following the cut-to-length harvesting system using Timberjack rubber-tired skidder. After finishing the harvesting OPERATIONs, damage to the bole, roots, extent of the damage, scars patterns, size and distribution was evaluated for all trees using stratified systematic sampling with a random start and fixed area plots. Results showed that scars occurred on 16.4% of the remaining trees, but the severity of scars varied significantly by species. Forty-six percent of scars for all species was considered as small size (>500cm2). The greatest average amount of damage to the bole occurred along the first 1 m up from the ground (93%) and also within 3 m of the skid trail centerline (86.4%). Gouges were present on 79% of all scars. The stratification of the study unit would effectively improve the accuracy of stand damage surveys.

Using modern machinery for logging will entail considerable pressure to the soil and cause serious damage to the soil and reduce the carbon sequestration. Many studies show the long-term recovery of soil physical and chemical properties. The aim of this study was to investigate the effects of SKIDDING slope, traffic, and place of the wheel on the carbon stocks and estimate the economic value of these reserves to obtain the information needed for comprehensive decision-making about the management of forest resources. The treatments included two slope classes (>10% and £10%), each class includes three traffic levels (low, medium and high), and in each group, on the wheels route, middle route, and control area, four samples were taken in three replicates. The economic valuation of the carbon sequestration function was determined using the shadow value method. The results showed that with increasing the slope path, the number of traffic and on the wheel route, the amount of carbon sequestration decreased significantly. The value of each hectare of the study area in terms of soil carbon sequestration and organic layer up to a depth of 10 cm was estimated about 1798.8 $ per hectare. On the other hand, reducing carbon sequestration in skid trails costs an average of 5, 166 $ per hectare annually. Awareness of these costs will help the policymakers in the conservation and allocation of financial resources, especially in the context of budget constraints.

Assessment and management of the environmental impacts of forest harvesting OPERATIONs have become increasingly critical factors in practicing commercial forestry. This study investigated soil disturbance from a forest logging system OPERATION on an 8-hectare mixed broadleaved stand in compartment no. 309 in Gorazbon district in Kheyrud educational and research forest. The objective of this study was to assess soil disturbance from ground-based SKIDDING system OPERATION contribute to statistically significant changes in bulk density and penetration resistance at various depths below the soil surface and changes in bulk density and penetration resistance related to different traffic intensities. A systematic predetermined grid that was laid out prior to harvesting to measure soil disturbance, and pre-and post soil disturbance were recorded by a visual assessment. Soil compaction and penetration resistance were measured by using a double sampling method consisting of a hammer driven hand corer and a hand-held soil penetrometer. Bulk density and soil strength measurements were taken at three depths: 10, 20 and 30 cm. Detrimental compaction was recorded for the soil bulk density results. Detrimental compaction was recorded for the soil penetrometer after medium and intense machine passes. Post-harvest detrimental soil disturbance wasn’t exceeded the USFS maximum allowable area that can be detrimentally impacted. Soil resistance results demonstrated no detrimental compaction in area to the skid trail center and wheel ruts.

It is necessary to review and evaluate the OPERATION of the system and determine appropriate methods forests due to topographic conditions are significant OPERATIONal activities, products, transportation, and the road making the destructive activities of the Forest as the most expensive. In this study, Economic Evaluation to be considered LTT-100A SKIDDING system upward. After field OPERATION and time study, using the regression model, the model is proposed to predict SKIDDING time. Among the components of each cycle SKIDDING in Zetor, moving with load and moving empty most of the time per cycle and in the form of delays, technical delays included the most time. The model predicted the SKIDDING time Zetor have meaningful SKIDDING distance and slope. hourly production rate of 12.5 cubic meters per hour and the cost of producing these systems is achieved 119, 795 rials per cubic meter. Because of the speed and its efficiency Zetor is low, thus in long intervals and in places where travel time is limited, use of this system is not recommended for SKIDDING OPERATIONs. But since the power of this machine is its high and rapid stabilization is done, the application of this system, is recommended to be combined with other systems.

Background and Aim: Different surgical techniques have been proposed for crown exposure among patients under orthodontic treatment. The aim of this study was to investigate periodontal indices in closed flap OPERATION technique used for impacted teeth crown exposure.Materials and Methods: In this descriptive study (2001-2003) 20 patients (15 females and 5 males), age ranging from 15 to 20 years, were participated. Following the performance of closed flap OPERATION technique, in 12 patients impacted canine and central incisors were exposed and treated orthodontically. Periodontal parameters including sulcular depth, width of keratinized gingiva and attachment loss were recorded. Results: The mean of gingival sulcus depth was 1.50±0.43, the means of keratinized gingival in central incisors and canines were 3.07±0.53 and 2.30±0.42, respectively. In one patient, attachment loss was reported.Conclusion: Considering the optimal sulcular depth and keratinized gingiva, the closed flap OPERATION technique seems suitable.

The optimum road spacing has been studied by many researches. It is an important step of forest road network planning. The goals of this study are determining the optimum road spacing in Kheiroudkenar forest of Nowshahr in Northern Iran and study of effect of kind of skidder on SKIDDING cost and road spacing. Continues time study method was used to determine the production rate of TAF and Timberjack 450 C skidders in two districts of Kheiroudkenar forest. The production models were developed using stepwise regression method with 46 working cycles for TAF and 44 for Timberjack. The total road construction and SKIDDING cost were calculated for different road spacing for both skidders in one-way and two-way SKIDDING. Based on minimizing the sum of the road and SKIDDING costs, the optimum road spacing was estimated as 1714 m and road density of 5.8 m/ha for two-way SKIDDING by Timberjack and estimated optimum road spacing of TAF was 1600 m and road density of 6.25 m/ha. For one-way SKIDDING, the optimum road spacing of Timberjack was 1143 m and road density of 8.8 m/ha, for SKIDDING by TAF, the optimum spacing was estimated as 1114 m and road density of 8.97 m/ha. The existing road density of Timberjack and TAF SKIDDING sites was 28.16 and 17.11 m/ha respectively which are higher than optimum density. The study of variants method is applied to find the optimal network for existing network in Namkhaneh district.

The effects of traffic frequency and skid trail slope on dry bulk density, litter mass and rutting are examined. Treatments included a combination of four different traffic frequencies (3, 7, 14, and 20 passes of a rubber skidder) and three levels of slope (<10%, 10%-20% and>20%.) The results showed that dry bulk density, rut depth and soil displacement increased with the increase of traffic frequency and slope, but floor coverage decreased. Within each traffic treatment soil compaction raised with the increase of skid trail slope, so that significant differences in dry bulk density were observed between slope of<20% and those one >20%. Bulk density has become quite close to the critical value after 14 cycles. With increase of the skidder cycles from 14 to 20, bulk density remained approximately constant. We observed soil displacement on the treatments with 7 cycles: rutting on the treatments started with 7 cycles and slope of>20%. Soil disturbance increased significantly on slopes with>20 % inclination with a dry bulk density of 1100 kg m-3 after 3 cycles compared to 830 kg m-3 on slopes<10 %. In addition the forest floor mass on the treatments with 7 cycles and slopes of>20% (437.6 kg/ha) was significantly (p<0.05) lower than treatments with 14 cycles and slopes of<10% (841.4 kg/ha.) Data suggest that disturbance increased earlier in the steep treatments than in less sloping conditions. The dramatic increase of soil disturbance on treatments with slopes of>20% may be associated with increasing load on the rear axle combined with slipping on steep slope trail.