Soil Compaction and Porosity Changes Caused During the Operation of Timberjack 450C Skidder in Northern Iran (original) (raw)
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Soil disturbance caused by different skidding methods in mountainous forests of Northern Iran
Harvest traffic with heavy equipment causes damage to forest soils. Whereas increased soil damage has been reported with increasing harvest equipment traffic and on increasing slope gradients, it is unclear how much soil damage is caused by different types of harvesting equipment. We visually assessed 16 categories of soil surface disturbances and measured soil bulk density, porosity, and rut depth on skid trails following increasing harvest traffic intensities by two rubber-tired skidders, a crawler skidder, and a mule. Regardless of the skidding type, the most severe soil disturbances were observed where equipment traffic was most frequent and on steeper slope gradients. The different skidding equipment resulted in different proportions of disturbed soil areas that ranged from 61.5% of harvested area for mule hauling to 70.3% for skidding with a crawler skidder, 76.6% for skidding with a Timberjack 450C skidder, and 87.1% for skidding with a TAF E655. Shallow disturbances, slash cover, and apparent compaction (i.e. a deep soil disturbance) were the most common types of machine-induced soil disturbance. Mule hauling did not cause any deep soil disturbance. Results showed that bulk density increased with traffic intensity regardless of the skidding method used and the slope of the skid and mule trails. Porosity decreased in the surface layer (0–10 cm) with increasing number of passes and the impact increased with increasing slope. Rutting was not observed when skidding with a crawler skidder or hauling with a mule. The results indicated that equipment type, traffic intensity, and slope gradient had strong effects on the physical properties of the soil.
Soil compaction caused by 450C Timber Jack wheeled skidder (Shefarood forest, northern Iran)
Journal of Forest Science
In forest harvesting operations usually after using skidding machinery (skidders), traces of soil damage in the form of soil compaction and wheel and logs ruts can be seen in the forest soil. Soil bulk density, which represents soil compaction, decreases soil porosity, infiltration rate and aeration and these in turn increase runoff and water erosion in the harvested area. On the other hand, a decrease in soil aeration prevents root growth and decreases the vegetative cover. In this study the changes in soil bulk density and relative soil compaction due to a different number of wheeled skidder passes from stump to landing for two soil types (clay soil with high and low liquid limits, CH, CL) are analyzed. The results showed that the effect of skidder traffic on an increase in soil bulk density at sample locations was significant (α = 0.05). The range of soil bulk density increases in sample pits due to a different number of machinery passes was from 15.8% to 62.6% compared to the co...
Journal of Forestry Research, 2010
A study was conducted to investigate the effects of skid trail slope and traffic levels on soil disturbances at two soil depths (0−10 and 10−20 cm). The treatments were set at four traffic levels (2, 7, 12 and 20), two slope classes (<20% and >20%) and two soil depths (0−10 and 10−20 cm). Results show that skidder traffic, longitudinal slope and soil depth have significant effect on soil bulk density in skid trail. Comparison of average soil bulk density in different traffic levels shows that there are significant differences in average bulk density between different traffic levels and control (p<0.05). The average bulk densities in different slopes and soil depths are significantly increased with increase in traffic levels, maximized at 12 passes (p<0.05), but there are no significant differences between 12 and 20 passes. The interaction effects between traffic and soil depth are significant (F0.05,3=0.109, p<0.001). For all traffic treatments, there are significant differences in soil moisture content between the two slope classes and the two depths (p<0.001). However, the interaction effects between traffic levels and slope classes are not significant (p >0.05), although skidder traffic and slope affected soil moisture content.
2017
Harvest traffic with heavy equipment causes damage to forest soils. Whereas increased soil damage has been reported with increasing harvest equipment traffic and on increasing slope gradients, it is unclear how much soil damage is caused by different directions of skidding. We examined the effects of traffic frequency, skid trail slope and skidding direction on the dry bulk density and total porosity of skidding trail soil in an Iranian temperate forest. The studied treatments included combinations of three different traffic frequencies (3, 7, and 12 passes of a rubber-tired skidder), three levels of slope (<10%, 10–20% and >20%) and two skidding directions (uphill and downhill). The impact on soil properties was greatest during the skidder initial passes. On steep slopes, only three skidder passes were required to cause substantial increases in soil bulk density relative to control plots, regardless of skidding direction. Independently of the traffic frequency and trail slope...
Effects of ground-based skidding on forest soil in Hyrcanian forest
2011
The use of rubber-tired skidders is a well accepted practice for the extraction of timber from the forest, but the application causes considerable environmental problems. The aim of the study was to evaluate the effects of slope gradient, number of machine passes on skid trails, soil depth, and soil moisture on soil compaction and rutting in a fined grained soil. The study was designed as a factorial experiment with the factors including slope gradient, soil moisture, and depth in the skid trail and number of machine passes. The effects of four slope classes (flat, 10%, -10%, and -20%), three soil depth classes (5 cm, 15 cm, and 25 cm), and different compaction levels based on various number of machine passes (0, 1, 5, 8, 10, 15, 20, 25, and 30) were evaluated. A Timberjack cable skidder was used and the study location was in the Kheyrud Educational and Research Forest located in Hyrcanian forest in northern Iran. The increased number of machine passes increased soil bulk density, b...
Skidding operations induce considerable and wide spread soil disturbance. It is unclear how much additional damage is caused by increased soil moisture content at the time of skidding. We visually assessed 16 categories of soil surface disturbances, measured surface layer bulk density, porosity, and rutting in two oriental beech sites in northern Iran following five frequencies of traffic on two slope gradients with 19% and 33% soil moisture content. At both moisture contents, the most severe soil disturbances occurred with more frequent equipment traffic and on steeper slopes. Soil disturbances were detected on 65% of the harvested area at lower and 87% at higher moisture content. Bulk density, porosity, and rut depth were significantly affected by traffic frequency, trail slope and moisture content. Bulk density nearly reached critical values of 1.4-1.55 g cm–3 after 7 passes at higher and 12 passes at lower moisture content. Adverse effects on porosity caused by increased traffic and trail slope increased with increasing soil moisture content. Rutting was observed after one and seven passes at high and low moisture content, respectively, and was deeper on steeper slopes. To minimize disturbance, groundbased skidding should be limited to times when soil moisture content is low.
Silva Fennica, 2012
Ground-based skidding can have detrimental effects on soil properties trough soil profile disturbance and compaction that can persist for decades. We investigated the recovery of physical properties of disturbed brown soils on four abandoned downhill skid trails in a deciduous mountain forest in northern Iran. The most recent skidding operations had taken place 1â5Â yrs, 6â10 yrs, 11â15 yrs, and 16â20 yrs ago, providing a 20-year chronosequence with four 5-year recovery periods. For each recovery period, mean values for soil bulk density (BD), total porosity (TP), macroporosity (MP), soil moisture content (SM), and rut depth (RD) were assessed for three levels of traffic intensity (Primary (PS), Secondary (SS) and Tertiary (TS) skid trails) and two levels of slope gradients (Gentle (G) and Steep (S)) and compared to those in undisturbed (control) areas. Over the 20-year recovery period, PS trails on gentle slopes exhibited mean values that were 35â42% (BD), 3â7% (SM), an...
2015
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