جستجوی مقالات مرتبط با کلیدواژه "soil compaction" در نشریات گروه "جنگلداری"

Assessment and management of environmental impacts imposed by forest harvesting activities are one of the key factors that are increasing important. The purpose of this study was to investigate the effect of ground-based system on soil physical and chemical properties and the recovery process of these properties over the course of seven years. Hence, the compartments no. 316, 318, 310, and 309 of the Gorazbon District in the Kheyrud educational and research forest were selected. In this study, a completely randomized factorial design was applied and the treatments included duration (years) from timber extraction (one, two, five, and seven years), three traffic intensities (low, medium, and high) and soil depths (0-10 and 10-20 cm). The soil bulk density after seven years has not yet returned to the original state. There is still a significant difference between the control area and the skid trail. The amount of organic matter after seven years showed a recovery process compared with the first year after timber extraction, so that in the seventh year no significant difference was observed between the amount of organic matter in the control area and timber extraction track, while the amount of organic matter in the first year of timber extraction track is much lower than that of adjacent control areas. The recovery of some soil properties such as organic matter occurs faster than other ones like bulk density and porosity.

Using machinery wood extraction in steep slope in the Hyrcanian forests can increase the soil bulk density and soil compaction, decrease the infiltration water into soil of skid trail, which results in an increase runoff and soil loss and has detrimental effects on soil nutrients loss and sedimentation into the downstream infrastructure. The aim of this study was to investigate the optimal distance of water diversion in skid trails to mitigate sthe ediment and runoff in compartments 315 and 316 of Gorazbon district in Kheyrud forest. In this study, 9 plots with length of 20, 30 and 40 m and slope gradient of 15, 25 and 35% were established along the longitudinal slope of the skid trails. A tank was installed to collect runoff at the outlet of each plot. Also, runoff in each rain event as well as soil bulk density, moisture content, organic matter, and soil texture of the plots were measured. The results revealed that the optimal distance among water diversions in the skid trails to suppress the runoff was 30 m and the most appropriate slope for mitigating runoff on the skid trails was up to 25% slope gradient. Runoff had a significant relationship with plot length. The results showed that the amount of rainfall was significantly correlated with runoff at different lengths and slopes. Therefore, it should be avoided to plan the skid trails on steep slopes for mitigating runoff, and some engineering measures such as the installing water diversion structures (by length of 30 m and slope gradient of 20-25%) to decrease the runoff should be done.

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.

The role of forest engineering is crucial for restoring and reclaiming of skid trails, one of these being to reduce sediment yields along the trails. This study aimed to measure sediment yield in the skid trails covered by different organic mulches and to compare it with an untreated trail and control plot (i.e., undisturbed forest). This research was conducted for 13 months (from September 2017 to October 2018) in the Namkhaneh district, Kheiroud forest, Nowshahr under the natural rainfall condition. Six-square-meter plots were used in three replications to determine the amount of sediment. Three natural mulch treatments were used in this study, including sawdust, leaf litter, and straw, and there were mulched at three different rates (based on material weight). The highest and lowest amount of sediment was obtained in the untreated skid trail and undisturbed forest, respectively. Our results demonstrated that the application of sawdust, straw, and leaf litter mulches reduced the sediment yield by 13.1, 10.2, and 7.3 times compared to the untreated trail, respectively. Overall, it can be concluded that the application of mulches, especially sawdust, has a significant impact on sediment reduction.

Although livestock grazing is known as a historic disturbance in forest ecosystems, but we still need more understanding about how it can affect soil properties. The purpose of this study was to investigate the effect of grazing intensity and type of livestock on the physical and chemical properties of soil in the Armardeh forests, Baneh County in the Kurdistan Province. Therefore, five areas were selected with different grazing intensity and livestock types. In total, 68 soil samples from 0-10 cm depth were taken and the most important physical and chemical soil factors including N, P, K, SOM, soil texture, and compaction were measured. Redundancy Analysis (RDA) method and CANOCO software were used to analyze the data. The results revealed that environmental variables are able to interpret 58.9% of the total variation. Four variables including stocking rate in grazing season, (Maraz goat+Mo goat+ sheep and cow), Mo goat+sheep, and finally Q. libani-Q. infectoria forest-type were selected as the most important variables in forward selection of RDA and responsible for 42.1% of total variation. Soil properties showed the most similarity between control and second treatment (Maraz goat with low-density grazing) and with generally lower soil compaction and higher SOM, N, K and P. On the contrary, the fifth treatment had the highest soil compaction and the lowest soil nutrient level. In conclusion, Maraz goat associated with low-intensity grazing rate caused lower effects on physical and chemical properties of soil in the study area and it can be recommended to local herder as a better adapted livestock to the Zagros oak forests.

In this study, Nano-polymer CBR PLUS is sued for soil stabilization in forest roads. Tests were carried out to identify the texture, Atterberg limits, compaction and CBR on the control and treated soil samples with different percentage of 0.25%, 0.50%, 0.75% and 1%. In order to study the mechanical characteristics of upper layer, five plots including one control plot (untreated) and four sample plots were carried out on forest road. The results showed that the Nano-polymer reduced liquid and plastic limits. By increasing the percentage of CBR PLUS, the soil fine particles decreased in control and treated samples, in which that 1% treatment has the minimum content in weight percent of soil fine particles and maximum content in coarse particles compare to other treatments. Also soil treated with CBR PLUS, reduces the optimum moisture content and increases maximum dry density and California Bearing Capacity (CBR). Investigation of chemical properties showed that the amount of Calcium, Magnesium and Potassium increased in runoff. It was concluded that 1% of Nano-polymer CBR PLUS acted better in comparison with other treatments.

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.

Forest harvesting operations for extracting of forest products in these trails, causing extensive damage in a wide range of soil and its productivity every year, therefore it is necessary to research about degradation of soil properties should be down. The aim of this study was investigate changes in the skid trails soil physical characteristics due to wheeled cable skidder traffic by measuring soil texture, bulk density, porosity and soil penetration resistence. For this purposes, 311 and 319 compartments of Gorazbon district in Kheyrud educational and research forest were selected. This study was conducted in a completely randomized factorial design and treatments consisted of two slop (uphill and downhill), three levels of skidder traffic intensity such as low intensity (less than 3 passes), moderate (3 to 7 passes) and very large (more than 7 passes) and two soil depths (0-10 and 10-20 cm).The results showed that machine traffic intensity and skid trail slop statistically had significant effects on soil compaction. Soil compaction and penetratin resistance will increase with increasing of machine traffic, but the largest percentage increase observe in initial passes (less than 3 times) although subsequent passes change this factors, but its trend is not significant, also soil compaction is greater than in the uphill skidding of downhill skidding and in the 0-10 cm soil depth greater than 10-20 cm. Hence, we concluded that skidding operation should be planned in slope lower than 20% and uphill skidding (higher than 10%) should be excluded from ground-based logging systems.

Tractor-based logging systems are the most common type of small-scale equipments. Farm tractors equipped with a 2-wheel trailer are mostly used to perform forwarding operations of pulpwoods and fuelwoods in the Hyrcanian forests of Iran. This study was carried out in Gorazbon district of Khyrud forest. The aim of the study was to evaluate effects of slope gradient، tractor traffic intensity over skid trails and soil depth on brown soil bulk density (BD)، total porosity (TP) and penetration resistance (PR) with clayey loam to loamy texture. The trial was conducted under the completely randomized factorial design at three replicates and three treatments، including: three slope gradients (0-10% (downhill)، 10-20% (downhill) and 0-10% (uphill))، three traffic intensity classes (<5، 5-10 and >10 passes) and four soil depths (5، 10، 15 and 20 cm) on skid trails and undisturbed locations adjacent to the study area. Results indicated that mean BD was significantly influenced by slope gradient، traffic intensity and soil depth. Skid trail on the uphill tractor forwarding slopes، showed the greatest value among the other ones. Results showed that TP significantly decreased as number of machine passes increased and high level of decrease occurred after further than 10 machine passes performed (TP= 38. 6%). Skid trail on the uphill tractor forwarding slopes showed the greatest PR value among the other ones. Penetration resistance increased significantly by increase in soil depth under the skid trails. Skid trails with 0-10% slope (downhill) had the lowest BD and PR values، whereas the trails with 10-20% slope (downhill) had the moderate values and the trails with 0-10% slope (uphill) had the highest compaction values. Overall، it might be concluded that forwarding operations with farm tractor should be planned in gentle slopes and uphill forwarding should be excluded from ground-based logging systems، if it’s possible.

Soil properties affected by passing the machines in skid trails and establishment of natural regeneration and herbaceous palnts in these routes after the harvesting operation could be a suitable opportunity to study the reaction of different plant species to soil conditions. This study has been done in district 1 of Nav forest, Guilan/Iran. The skid trails where have been abandoned without traffic for 10 years were chosen among the available skid trail routes. Soil samples were taken and type and the number of natural regeneration in skid trials and adjacent forests (natural forests) wre recorded. The results showed that among soil physical properties, soil bulk density, porosity, saturation moisture percentage and soil texture differed significantly between skid trail routes and natural forest. The natural regeneration of cappadocia maple, hornbeam and alder showed significant difference between natural forest and skid trails routs, while natural regeneration of beech and Velvet maple did not show any significant differences. The regeneration of alder was significantly higher in skid trail routes compared to natural forests, but for hornbeam and maple this regeneration was better in natural forest. Among soil physical properties, bulk density, porosity and soil texture showed significant correlation with amount of natural regeneration and among tree species, cappadocia maple showed the higher correlation with soil physical properties. This study showed that the natural regeneration of some species is affected by soil physical properties. In addition to the determination of natural regeneration responses to soil physical properties, the results of this study could be used in silviculture and forest management.