Ahmad Solgi - Academia.edu (original) (raw)
Papers by Ahmad Solgi
International Journal of Forest Engineering, 2024
Soil profile disturbance and compaction can have a medium-term detrimental impact on soil physica... more Soil profile disturbance and compaction can have a medium-term detrimental impact on soil physical properties. We investigated the recovery of physical properties of disturbed soils on four abandoned skid trails in a deciduous mountain forest in northern Iran. The trails ranged from immediately after skidding operations (IAS), through 5 years and 10 years, to 20 years since forest harvesting. For each recovery period, mean values for soil bulk density, total porosity, macroporosity, and rut depth were assessed for three levels of traffic intensity and two levels of slope gradients, as well as within the general harvesting area and compared to those in untrafficked control areas. Over the 20-year recovery period, skid trails with lower traffic intensity on gentle slopes exhibited mean values that were 16.1% (bulk density), and 3.5 cm (rut depth) greater and 9.5% (total porosity) and 32.7% (macroporosity) lower compared to undisturbed areas; on steep trails with higher traffic intensity, values were 43.1% (bulk density), and 13 cm (rut depth) greater and 30.3% (total porosity) and 64.5% (macroporosity) lower, respectively. During this period (over the 20-year recovery period), surface soil compaction showed recovery in the general harvesting area. These results raise serious concerns about medium-term resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.
International Journal of Forest Engineering, 2023
Skidding operations affect soil physical properties, which may impact soil sustainability and for... more Skidding operations affect soil physical properties, which may impact soil sustainability and forest productivity. While the relationship among harvest machine traffic, slope gradients, and increased soil damage has been well-investigated, it is still unclear how soil damage due to repeated passes of different skidder types is interacting with soil moisture and slope conditions. We examined dry bulk density (BD), total porosity (TP), and rutting depth (RD) of skid trail soil in an Iranian temperate forest. The study took into consideration a combination of five different traffic intensities (TI) (1, 4, 8, 12, and 15 passes), two levels of slope gradients (SGs) (≤20% and > 20%), two rubber-tired skidder types (STs) (Timberjack 450C and TAF E655), and two soil moisture contents (SMC) (18% and 31%). Results showed that changes in BD and TP were mainly related to TI regardless of the ST and the skid trail slope. Regardless of TI, SG, and SMC, the TAF E655 skidder caused a higher dry BD increase and soil porosity reduction than the Timberjack 450C. Furthermore, the higher the SMC, the deeper the ruts at all combinations of TI, SG, and ST. Our findings highlighted that ST, SMC, TI, and SG strongly affect rutting and physical properties of soil.
iForest, 2023
The use of wheel skidders for timber extraction from tree stump to roadside landing has become mo... more The use of wheel skidders for timber extraction from tree stump to roadside landing has become more and more widespread. Although the use of wheel skidders has the advantages of high production and reduced extraction costs, it also damages the soil and impedes forest regeneration. The main purpose of this study was to investigate the effect of machine traffic using the Timberjack 450C (two, six and 15 passes) on two slope classes (SC) of skid trails. A low slope is considered to be <20% and a high slope is at >20%. The effects on soil physicochemical properties and seedling growth (alder, Alnus subcordata C.A. Mey. and maple, Acer velutinum Boiss.) in natural mixed beech stands in the Hyrcanian forests in Northern Iran were observed and studied. The results showed that the different factors of traffic intensity (TI) and SC had a significant impact on soil physicochemical properties and subsequent seedling growth. After two machine passes in a low TI on both low and high slopes, soil bulk density (BD) increased by 49.3% and 59.2% and penetration resistance increased by 30.5% and 38.5%, while total porosity decreased by 19.5% and 23.5%. The forest floor decreased by 30.9% and 42%, organic carbon decreased by 25.6% and 39.4%, nitrogen decreased by 18.5% and 26.3%, phosphorus decreased by 14.1% and 23%, and potassium decreased by 10.7% and 24.2%, respectively as compared with the control area. Our results indicated additional BD increments after two, six and 15 machine passes of 49.3%, 17.9% and 8.3% in the low slope, respectively, and 59.2%, 16.5% and 7.1% in the high slope, respectively. The mean of the germination rate (GR) of alder and maple seedlings in the control area was 58.3% and 46.1%, respectively, while after two, six and 15 passes, the GR of alder seedlings reduced to 50%, 46.4% and 37.5%, respectively, while that of maple seedlings reduced to 36.1%, 28.6% and 25.6%, respectively. Additionally, after two machine passes, stem length, main root length, and total dry biomass decreased by 28.7%, 34.9% and 34% in alder seedlings, respectively, and 27.9%, 27.6% and 33.3% in maple seedlings, respectively. Comparison of the response of the two seedling species to soil compaction showed that although alder had a higher GR than maple, the root growth of maple was higher than that of alder.
Forest Science, 2023
Mulches can be effective for reducing sediment loss and erosion from forest harvesting activities... more Mulches can be effective for reducing sediment loss and erosion from forest harvesting activities. This study evaluates the use of rice straw and sawdust as mulch covers for skid trails on clay loam soil. The treatments with three replications each included combinations of two levels of slope gradient (≤ 20% and > 20%), three types of mulch cover (bare soil, sawdust, and rice straw cover), three levels of mulching application schemes (1/3, 2/3, and 3/3 of the plot length), and two levels of surface cover rates (50% and 70%). Increasing levels of mulch cover had significantly lower runoff and sediment yields throughout the trails. The average runoff rates and sediment yield from the machine operating trails treated with sawdust cover (SC) (30.2 l and 2.7 g m-2) were lower than on trails covered with rice straw mulch (RSC) (36.8 l and 3.5 g m-2), which were, in turn, lower than on untreated bare soil (BS) trail sectors (48.80 l and 5.34 g m-2). Overall, mulching was more effective when applied over the entire plot length than over the 1/3 and 2/3 plots length strips, both in terms of runoff and sediment yield. Study Implications: We found that soil loss depended strongly on the slope gradient. Mulch cover had a significant improvement effect on the surface runoff and sediment yield, and mulching was more effective when applied over the entire plot length.
Caspian Journal of Environmental Science, 2024
Among the various factors affecting soil compression during wood extraction, travel speed hasn't ... more Among the various factors affecting soil compression during wood extraction, travel speed hasn't received much attention. The aims of this study were to (a) assess the effects of two frequently employed wood extraction machines, namely a tractor (Massey Ferguson 285) and a skidder model (Timberjack 450C), equipped with different tire sizes and uneven axle loads with regard to forest soil physical properties and rut formation under various traffic frequencies and travel speeds, and (b) examine the relationship between travel speed and soil bulk density. Treatments included six different traffic frequencies (0, 1, 3, 6, 10 and 15 passes) and three travel speed levels (1, 3 and 5 m s-1) of the two tractors. The number of passes, machine type, and travel speed all show significant effects (p < 0.05) on bulk density, total porosity, and rut depth. The skidder exerted statistically significant. Bulk density positively correlated with traffic intensity in all examined levels of travel speed. Porosity in the topsoil (0-10 cm) decreased by an elevating number of passes and this trend was also evidenced as the travel speed decreased. Furthermore, the skidder created, in all cases, deeper ruts than those generated by the tractor. Considering the imminent end of the ban on wood harvesting in the study area in 2016, these insights have practical implications for forest management and wood extraction practices. Forest managers should carefully consider the choice of wood extraction equipment and operational parameters, especially travel speed, to minimize soil compaction and rut formation. The implementation of strategies that support sustainable soil management practices during the wood extraction are paramount to preserving the long-term health and productivity of forest ecosystems.
International Journal of Forest Engineering, Apr 19, 2022
ABSTRACT Machine traffic during wood harvesting causes damage to forest soils. Whereas increased ... more ABSTRACT Machine traffic during wood harvesting causes damage to forest soils. Whereas increased soil damage has been associated with increased traffic frequency and soil water content, the impact of travel speed on soil disturbance, still remains unclear. We examined the effects of traffic frequency, travel speed, and soil water content on the dry bulk density, total porosity and rut depth of skidding trail soil in an Iranian temperate forest. The studied treatments included combinations of five traffic frequencies (1, 3, 7, 10, and 15 passes) of a rubber-tired skidder, three levels of travel speed (1, 3, and 5 m s−1) and two levels of soil water content (18% and 31%). The impact on soil properties was greatest during the initial skidder passes. At higher water content, only one skidder pass was required to cause substantial increases in soil bulk density compared to the control plots, at all travel speed levels. Regardless of traffic frequency and water content, a lower travel speed caused substantially greater increases in dry bulk density and greater decreases in soil porosity than did a higher travel speed. Furthermore, higher soil water content resulted in deeper ruts at all combinations of traffic intensity and travel speed. In conclusion, fewer skidder passes at a slower travel speed were required to achieve substantial soil disturbance than was the case at a faster travel speed, possibly due to the higher amount of vibration, and consequently compaction exerted during a machine pass at a slower speed.
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.
Croatian Journal of Forest Engineering, 2022
Forest operations can lead to increased runoff and soil loss on roads and skid trails. The aim of... more Forest operations can lead to increased runoff and soil loss on roads and skid trails. The aim of this study was to evaluate the effectiveness of two erosion control treatments applied to different segments of skid trails following six natural rainfall events. A total of 162 plots 10 m long by 4 m wide were established in a Hyrcanian deciduous forest to assess soil runoff and soil loss following ground-based harvesting traffic. The experimental setup consisted of three levels of traffic intensity (three, eight and 16 skidder passes), two levels of slope gradient (≤20% and >20%), three classes of curvature (narrow = high deflection angle, 60°-70°; wide = low deflection angle, 110°-130°, and straight trail segments), and three classes of mulch cover (bare soil, sawdust cover, and rice straw cover). Each treatment combination was replicated three times, yielding 972 soil samples. The average surface runoff volume and soil loss differed significantly between the switchbacks and the straight trail segments and depended strongly on the degree of curvature, with severity of adverse effects increasing with curve tightness. Mulch cover treatments had a significant ameliorating effect on the surface runoff volume and soil loss throughout the skid trail. The average runoff and soil loss from the skid trails treated with sawdust cover (SC) (0.24 l m-2 (mm) and 0.49 g m-2 , respectively) were lower than on trails covered with rice straw (RSC) (0.45 l m-2 and 1.19 g m-2 , respectively), which were, in turn lower than on untreated bare soil (BS) trail segments (0.70 l m-2 and 2.31 g m-2 , respectively). Surface runoff volume was significantly positively correlated with soil loss and both were positively correlated with dry bulk density and rut depth and negatively correlated with litter mass, total porosity, and macroporosity. Surface cover is a successful measure for controlling erosion losses following skidding disturbances, particularly in the switchback curves of trails on steep slopes where erosion potential is high.
Croatian journal of forest engineering, 2021
Forest operations can lead to increased runoff and soil loss on roads and skid trails. Best manag... more Forest operations can lead to increased runoff and soil loss on roads and skid trails. Best management practices (BMPs) aim to minimize erosion and water quality problems, but the efficacies of various BMP options such as water bars are not well documented. The aim of this study was to evaluate the effects of different densities of water diversion structures (water bars) on runoff volume and soil loss on different skid trail gradients on two soils with different textures in the Shenrood forest, Guilan province, northern Iran. The treatments included combinations of four densities of water bars (1, 2, 3 or 6 water bars per 150 m length of skid trail section [overland trail]), on two levels of trail gradient (≤20% and >20%) and two soil textures (clay loam and silt loam). Average runoff volume and soil loss per m2 of skid trail surface area were significantly greater (P≤0.05) on silt loam than on clay loam textured soils, and on slope gradients >20% (23–28%) than on gradients ≤2...
Croatian journal of forest engineering, 2021
Forest operations often enhance runoff and soil loss in roads and skid trails, where cut slopes a... more Forest operations often enhance runoff and soil loss in roads and skid trails, where cut slopes and fill slopes are the most important source of sediment. This study evaluated the effectiveness of four erosion control treatments applied to cut slope and fill slope segments of forest roads of different ages in the Hyrcanian forest in northern Iran. The treatment combinations, each replicated three times, included four classes of mulch cover (bare soil [BS], wood chips cover [WCH], sawdust cover [SC], and rice straw cover [RSC]), two levels of side slope (cut slope and fill slope), two levels of side slope gradient (20–25% and 40–45%), and three levels of road age (three, 10 and 20 years after construction). Mulch cover treatments significantly reduced average surface runoff volume and sediment yield compared to BS. Regardless of erosion control treatment, greater surface runoff volume and soil loss under natural rainfall occurred on steeper slope gradients in all road age classes and...
An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 ... more An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 skidding cycles) (i.e. pass back and forth on the skid trail) and skid trail slope (0-10, 10-20, and > 20)% on soil compaction, forest floor removal, and rut depth after logging. The results showed that dry bulk density and rut depth 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 slopes lower than 20% and those greater than 20%. Bulk density has become quite close to the critical value after 15 cycles. We observed soil rutting on the treatments started with 10 cycles. Soil disturbance increased significantly on slopes with less than 20% inclination with a dry bulk density of 1.157 g cm-3 after 5 cycles compared to 0.923 g cm-3 on slopes lower than 10%. In addition the litter mass on the treatments with 10 cycles and slopes greater than 20% (386.586 kg ha-1) was significantly lower (p < 0.05) than treatments with 15 cycles and slopes lower than 10% (545.382 kg ha-1). 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 greater than 20% may be associated with increasing load on the rear axle combined with slipping on steep slope trail.
The paper investigated the effects of ground-based skidding on soil physical properties. For this... more The paper investigated the effects of ground-based skidding on soil physical properties. For this purpose, soil disturbance following skidding was assessed for four levels of traffic intensity and three levels of slope gradients; each combination replicated three times. Soil samples were collected from the depth interval of 0-10 cm before and after traffic with a Timberjack 450C skidder in control areas and on skid trails. All soil response measures revealed detrimental compaction and porosity conditions in the skid trails, particularly on steep slopes >20%. The results clearly showed that most of the potential impact occurred after the initial passes. Substantial increases in bulk density appeared right after the first two skidder passes on steep slopes. Regardless of traffic intensity, however, dry bulk density and microporosity increased and total porosity, macroporosity, void ratio and soil moisture content decreased considerably regardless of slope gradient. Nonetheless, com...
Madera Y Bosques, 2015
Se realizo un extenso estudio de campo para examinar la influencia de la intensidad de trafico (5... more Se realizo un extenso estudio de campo para examinar la influencia de la intensidad de trafico (5, 10 y 15 ciclos de arrastre) (es decir, pasar de ida y vuelta en la pista de arrastre) y de la pendiente del terreno de arrastre (0-10, 10-20 y mas de 20)% en la compactacion del suelo, remocion suelo del bosque y la profundidad de la huella despues de la tala. Los resultados mostraron que la densidad de masa seca y la profundidad de las raices se incrementan conforme lo hacen la frecuencia del trafico y la pendiente y que la cobertura de suelo disminuyo. Dentro de cada tratamiento de trafico, la compactacion del suelo aumento con el incremento de la pendiente del terreno, se observaron diferencias significativas en la densidad aparente seca entre la pendiente menor a 20% y la mayor a 20%. La densidad aparente se acerca a su valor critico despues de 15 ciclos. Se observo la formacion de surcos en el suelo en los tratamientos de 10 ciclos. La perturbacion del suelo aumento significativam...
An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 ... more An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 skidding cycles) (i.e. pass back and forth on the skid trail) and skid trail slope (0-10, 10-20, and > 20)% on soil compaction, forest floor removal, and rut depth after logging. The results showed that dry bulk density and rut depth 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 slopes lower than 20% and those greater than 20%. Bulk density has become quite close to the critical value after 15 cycles. We observed soil rutting on the treatments started with 10 cycles. Soil disturbance increased significantly on slopes with less than 20% inclination with a dry bulk density of 1.157 g cm -3 after 5 cycles compared to 0.923 g cm -3 on slopes lower than 10%. In addition the litter ma...
International Journal of Forest Engineering, 2018
We quantified the effectiveness of different soil protective mat compositions (brush, sawdust, co... more We quantified the effectiveness of different soil protective mat compositions (brush, sawdust, combination of brush and sawdust) and densities (light density of 10 kg m−2 and heavy density of 20 kg m−2) on compaction and rutting on skid trails in mountainous forests following one, four, and 10 machine passes on two trail gradient classes (≤ 20% and > 20%). Soil bulk density and rut depth increased markedly with traffic frequency on both slope gradient classes on bare and protected soil, but soil protective mats delayed the onset of adverse soil responses and reduced the level of soil damage. Brush mats provided a more effective protection than sawdust and the combination of brush and sawdust and heavy density brush mats more so than light density mats. Compared to bare soil, heavy brush reinforcement significantly reduced bulk density for up to 10 passes on trail gradients ≤ 20% and four passes on gradients > 20%, regardless of soil protective mat composition. Light and heavy ...
Harvest traffic with heavy equipment causes damage to forest soils. Whereas increased soil damage... more 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...
The objective of this study was to compare forest soil bulk density values obtained through conve... more The objective of this study was to compare forest soil bulk density values obtained through conventional sampling methods such as the volumetric ring (VR: diameter 5 cm, length 10 cm) and paraffin sealed clod (PSC), with a variation of the VR, where rectangular boxes (RB) of four different dimensions were used. Sampling transects were established on a machine operating trail located in a beech (Fagus orientalis Lipsky) stand in Northern Iran. At each transect, three soil samples were collected at three different locations. Samples from different methods were spaced by a 50 cm distance to avoid direct interactions. The soil class of our study area was Combisols according to the WRB classification with a clay texture. Soil bulk density differed significantly between the three sampling methods. The lowest values were obtained with the RB (average 1.25 g cm), followed by the VR (average 1.40 g cm), and lastly the PSC (average 1.52 g cm). The values obtained with four variations of the R...
JOJ Horticulture & Arboriculture, 2018
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.
International Journal of Forest Engineering, 2024
Soil profile disturbance and compaction can have a medium-term detrimental impact on soil physica... more Soil profile disturbance and compaction can have a medium-term detrimental impact on soil physical properties. We investigated the recovery of physical properties of disturbed soils on four abandoned skid trails in a deciduous mountain forest in northern Iran. The trails ranged from immediately after skidding operations (IAS), through 5 years and 10 years, to 20 years since forest harvesting. For each recovery period, mean values for soil bulk density, total porosity, macroporosity, and rut depth were assessed for three levels of traffic intensity and two levels of slope gradients, as well as within the general harvesting area and compared to those in untrafficked control areas. Over the 20-year recovery period, skid trails with lower traffic intensity on gentle slopes exhibited mean values that were 16.1% (bulk density), and 3.5 cm (rut depth) greater and 9.5% (total porosity) and 32.7% (macroporosity) lower compared to undisturbed areas; on steep trails with higher traffic intensity, values were 43.1% (bulk density), and 13 cm (rut depth) greater and 30.3% (total porosity) and 64.5% (macroporosity) lower, respectively. During this period (over the 20-year recovery period), surface soil compaction showed recovery in the general harvesting area. These results raise serious concerns about medium-term resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.
International Journal of Forest Engineering, 2023
Skidding operations affect soil physical properties, which may impact soil sustainability and for... more Skidding operations affect soil physical properties, which may impact soil sustainability and forest productivity. While the relationship among harvest machine traffic, slope gradients, and increased soil damage has been well-investigated, it is still unclear how soil damage due to repeated passes of different skidder types is interacting with soil moisture and slope conditions. We examined dry bulk density (BD), total porosity (TP), and rutting depth (RD) of skid trail soil in an Iranian temperate forest. The study took into consideration a combination of five different traffic intensities (TI) (1, 4, 8, 12, and 15 passes), two levels of slope gradients (SGs) (≤20% and > 20%), two rubber-tired skidder types (STs) (Timberjack 450C and TAF E655), and two soil moisture contents (SMC) (18% and 31%). Results showed that changes in BD and TP were mainly related to TI regardless of the ST and the skid trail slope. Regardless of TI, SG, and SMC, the TAF E655 skidder caused a higher dry BD increase and soil porosity reduction than the Timberjack 450C. Furthermore, the higher the SMC, the deeper the ruts at all combinations of TI, SG, and ST. Our findings highlighted that ST, SMC, TI, and SG strongly affect rutting and physical properties of soil.
iForest, 2023
The use of wheel skidders for timber extraction from tree stump to roadside landing has become mo... more The use of wheel skidders for timber extraction from tree stump to roadside landing has become more and more widespread. Although the use of wheel skidders has the advantages of high production and reduced extraction costs, it also damages the soil and impedes forest regeneration. The main purpose of this study was to investigate the effect of machine traffic using the Timberjack 450C (two, six and 15 passes) on two slope classes (SC) of skid trails. A low slope is considered to be <20% and a high slope is at >20%. The effects on soil physicochemical properties and seedling growth (alder, Alnus subcordata C.A. Mey. and maple, Acer velutinum Boiss.) in natural mixed beech stands in the Hyrcanian forests in Northern Iran were observed and studied. The results showed that the different factors of traffic intensity (TI) and SC had a significant impact on soil physicochemical properties and subsequent seedling growth. After two machine passes in a low TI on both low and high slopes, soil bulk density (BD) increased by 49.3% and 59.2% and penetration resistance increased by 30.5% and 38.5%, while total porosity decreased by 19.5% and 23.5%. The forest floor decreased by 30.9% and 42%, organic carbon decreased by 25.6% and 39.4%, nitrogen decreased by 18.5% and 26.3%, phosphorus decreased by 14.1% and 23%, and potassium decreased by 10.7% and 24.2%, respectively as compared with the control area. Our results indicated additional BD increments after two, six and 15 machine passes of 49.3%, 17.9% and 8.3% in the low slope, respectively, and 59.2%, 16.5% and 7.1% in the high slope, respectively. The mean of the germination rate (GR) of alder and maple seedlings in the control area was 58.3% and 46.1%, respectively, while after two, six and 15 passes, the GR of alder seedlings reduced to 50%, 46.4% and 37.5%, respectively, while that of maple seedlings reduced to 36.1%, 28.6% and 25.6%, respectively. Additionally, after two machine passes, stem length, main root length, and total dry biomass decreased by 28.7%, 34.9% and 34% in alder seedlings, respectively, and 27.9%, 27.6% and 33.3% in maple seedlings, respectively. Comparison of the response of the two seedling species to soil compaction showed that although alder had a higher GR than maple, the root growth of maple was higher than that of alder.
Forest Science, 2023
Mulches can be effective for reducing sediment loss and erosion from forest harvesting activities... more Mulches can be effective for reducing sediment loss and erosion from forest harvesting activities. This study evaluates the use of rice straw and sawdust as mulch covers for skid trails on clay loam soil. The treatments with three replications each included combinations of two levels of slope gradient (≤ 20% and > 20%), three types of mulch cover (bare soil, sawdust, and rice straw cover), three levels of mulching application schemes (1/3, 2/3, and 3/3 of the plot length), and two levels of surface cover rates (50% and 70%). Increasing levels of mulch cover had significantly lower runoff and sediment yields throughout the trails. The average runoff rates and sediment yield from the machine operating trails treated with sawdust cover (SC) (30.2 l and 2.7 g m-2) were lower than on trails covered with rice straw mulch (RSC) (36.8 l and 3.5 g m-2), which were, in turn, lower than on untreated bare soil (BS) trail sectors (48.80 l and 5.34 g m-2). Overall, mulching was more effective when applied over the entire plot length than over the 1/3 and 2/3 plots length strips, both in terms of runoff and sediment yield. Study Implications: We found that soil loss depended strongly on the slope gradient. Mulch cover had a significant improvement effect on the surface runoff and sediment yield, and mulching was more effective when applied over the entire plot length.
Caspian Journal of Environmental Science, 2024
Among the various factors affecting soil compression during wood extraction, travel speed hasn't ... more Among the various factors affecting soil compression during wood extraction, travel speed hasn't received much attention. The aims of this study were to (a) assess the effects of two frequently employed wood extraction machines, namely a tractor (Massey Ferguson 285) and a skidder model (Timberjack 450C), equipped with different tire sizes and uneven axle loads with regard to forest soil physical properties and rut formation under various traffic frequencies and travel speeds, and (b) examine the relationship between travel speed and soil bulk density. Treatments included six different traffic frequencies (0, 1, 3, 6, 10 and 15 passes) and three travel speed levels (1, 3 and 5 m s-1) of the two tractors. The number of passes, machine type, and travel speed all show significant effects (p < 0.05) on bulk density, total porosity, and rut depth. The skidder exerted statistically significant. Bulk density positively correlated with traffic intensity in all examined levels of travel speed. Porosity in the topsoil (0-10 cm) decreased by an elevating number of passes and this trend was also evidenced as the travel speed decreased. Furthermore, the skidder created, in all cases, deeper ruts than those generated by the tractor. Considering the imminent end of the ban on wood harvesting in the study area in 2016, these insights have practical implications for forest management and wood extraction practices. Forest managers should carefully consider the choice of wood extraction equipment and operational parameters, especially travel speed, to minimize soil compaction and rut formation. The implementation of strategies that support sustainable soil management practices during the wood extraction are paramount to preserving the long-term health and productivity of forest ecosystems.
International Journal of Forest Engineering, Apr 19, 2022
ABSTRACT Machine traffic during wood harvesting causes damage to forest soils. Whereas increased ... more ABSTRACT Machine traffic during wood harvesting causes damage to forest soils. Whereas increased soil damage has been associated with increased traffic frequency and soil water content, the impact of travel speed on soil disturbance, still remains unclear. We examined the effects of traffic frequency, travel speed, and soil water content on the dry bulk density, total porosity and rut depth of skidding trail soil in an Iranian temperate forest. The studied treatments included combinations of five traffic frequencies (1, 3, 7, 10, and 15 passes) of a rubber-tired skidder, three levels of travel speed (1, 3, and 5 m s−1) and two levels of soil water content (18% and 31%). The impact on soil properties was greatest during the initial skidder passes. At higher water content, only one skidder pass was required to cause substantial increases in soil bulk density compared to the control plots, at all travel speed levels. Regardless of traffic frequency and water content, a lower travel speed caused substantially greater increases in dry bulk density and greater decreases in soil porosity than did a higher travel speed. Furthermore, higher soil water content resulted in deeper ruts at all combinations of traffic intensity and travel speed. In conclusion, fewer skidder passes at a slower travel speed were required to achieve substantial soil disturbance than was the case at a faster travel speed, possibly due to the higher amount of vibration, and consequently compaction exerted during a machine pass at a slower speed.
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.
Croatian Journal of Forest Engineering, 2022
Forest operations can lead to increased runoff and soil loss on roads and skid trails. The aim of... more Forest operations can lead to increased runoff and soil loss on roads and skid trails. The aim of this study was to evaluate the effectiveness of two erosion control treatments applied to different segments of skid trails following six natural rainfall events. A total of 162 plots 10 m long by 4 m wide were established in a Hyrcanian deciduous forest to assess soil runoff and soil loss following ground-based harvesting traffic. The experimental setup consisted of three levels of traffic intensity (three, eight and 16 skidder passes), two levels of slope gradient (≤20% and >20%), three classes of curvature (narrow = high deflection angle, 60°-70°; wide = low deflection angle, 110°-130°, and straight trail segments), and three classes of mulch cover (bare soil, sawdust cover, and rice straw cover). Each treatment combination was replicated three times, yielding 972 soil samples. The average surface runoff volume and soil loss differed significantly between the switchbacks and the straight trail segments and depended strongly on the degree of curvature, with severity of adverse effects increasing with curve tightness. Mulch cover treatments had a significant ameliorating effect on the surface runoff volume and soil loss throughout the skid trail. The average runoff and soil loss from the skid trails treated with sawdust cover (SC) (0.24 l m-2 (mm) and 0.49 g m-2 , respectively) were lower than on trails covered with rice straw (RSC) (0.45 l m-2 and 1.19 g m-2 , respectively), which were, in turn lower than on untreated bare soil (BS) trail segments (0.70 l m-2 and 2.31 g m-2 , respectively). Surface runoff volume was significantly positively correlated with soil loss and both were positively correlated with dry bulk density and rut depth and negatively correlated with litter mass, total porosity, and macroporosity. Surface cover is a successful measure for controlling erosion losses following skidding disturbances, particularly in the switchback curves of trails on steep slopes where erosion potential is high.
Croatian journal of forest engineering, 2021
Forest operations can lead to increased runoff and soil loss on roads and skid trails. Best manag... more Forest operations can lead to increased runoff and soil loss on roads and skid trails. Best management practices (BMPs) aim to minimize erosion and water quality problems, but the efficacies of various BMP options such as water bars are not well documented. The aim of this study was to evaluate the effects of different densities of water diversion structures (water bars) on runoff volume and soil loss on different skid trail gradients on two soils with different textures in the Shenrood forest, Guilan province, northern Iran. The treatments included combinations of four densities of water bars (1, 2, 3 or 6 water bars per 150 m length of skid trail section [overland trail]), on two levels of trail gradient (≤20% and >20%) and two soil textures (clay loam and silt loam). Average runoff volume and soil loss per m2 of skid trail surface area were significantly greater (P≤0.05) on silt loam than on clay loam textured soils, and on slope gradients >20% (23–28%) than on gradients ≤2...
Croatian journal of forest engineering, 2021
Forest operations often enhance runoff and soil loss in roads and skid trails, where cut slopes a... more Forest operations often enhance runoff and soil loss in roads and skid trails, where cut slopes and fill slopes are the most important source of sediment. This study evaluated the effectiveness of four erosion control treatments applied to cut slope and fill slope segments of forest roads of different ages in the Hyrcanian forest in northern Iran. The treatment combinations, each replicated three times, included four classes of mulch cover (bare soil [BS], wood chips cover [WCH], sawdust cover [SC], and rice straw cover [RSC]), two levels of side slope (cut slope and fill slope), two levels of side slope gradient (20–25% and 40–45%), and three levels of road age (three, 10 and 20 years after construction). Mulch cover treatments significantly reduced average surface runoff volume and sediment yield compared to BS. Regardless of erosion control treatment, greater surface runoff volume and soil loss under natural rainfall occurred on steeper slope gradients in all road age classes and...
An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 ... more An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 skidding cycles) (i.e. pass back and forth on the skid trail) and skid trail slope (0-10, 10-20, and > 20)% on soil compaction, forest floor removal, and rut depth after logging. The results showed that dry bulk density and rut depth 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 slopes lower than 20% and those greater than 20%. Bulk density has become quite close to the critical value after 15 cycles. We observed soil rutting on the treatments started with 10 cycles. Soil disturbance increased significantly on slopes with less than 20% inclination with a dry bulk density of 1.157 g cm-3 after 5 cycles compared to 0.923 g cm-3 on slopes lower than 10%. In addition the litter mass on the treatments with 10 cycles and slopes greater than 20% (386.586 kg ha-1) was significantly lower (p < 0.05) than treatments with 15 cycles and slopes lower than 10% (545.382 kg ha-1). 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 greater than 20% may be associated with increasing load on the rear axle combined with slipping on steep slope trail.
The paper investigated the effects of ground-based skidding on soil physical properties. For this... more The paper investigated the effects of ground-based skidding on soil physical properties. For this purpose, soil disturbance following skidding was assessed for four levels of traffic intensity and three levels of slope gradients; each combination replicated three times. Soil samples were collected from the depth interval of 0-10 cm before and after traffic with a Timberjack 450C skidder in control areas and on skid trails. All soil response measures revealed detrimental compaction and porosity conditions in the skid trails, particularly on steep slopes >20%. The results clearly showed that most of the potential impact occurred after the initial passes. Substantial increases in bulk density appeared right after the first two skidder passes on steep slopes. Regardless of traffic intensity, however, dry bulk density and microporosity increased and total porosity, macroporosity, void ratio and soil moisture content decreased considerably regardless of slope gradient. Nonetheless, com...
Madera Y Bosques, 2015
Se realizo un extenso estudio de campo para examinar la influencia de la intensidad de trafico (5... more Se realizo un extenso estudio de campo para examinar la influencia de la intensidad de trafico (5, 10 y 15 ciclos de arrastre) (es decir, pasar de ida y vuelta en la pista de arrastre) y de la pendiente del terreno de arrastre (0-10, 10-20 y mas de 20)% en la compactacion del suelo, remocion suelo del bosque y la profundidad de la huella despues de la tala. Los resultados mostraron que la densidad de masa seca y la profundidad de las raices se incrementan conforme lo hacen la frecuencia del trafico y la pendiente y que la cobertura de suelo disminuyo. Dentro de cada tratamiento de trafico, la compactacion del suelo aumento con el incremento de la pendiente del terreno, se observaron diferencias significativas en la densidad aparente seca entre la pendiente menor a 20% y la mayor a 20%. La densidad aparente se acerca a su valor critico despues de 15 ciclos. Se observo la formacion de surcos en el suelo en los tratamientos de 10 ciclos. La perturbacion del suelo aumento significativam...
An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 ... more An extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 skidding cycles) (i.e. pass back and forth on the skid trail) and skid trail slope (0-10, 10-20, and > 20)% on soil compaction, forest floor removal, and rut depth after logging. The results showed that dry bulk density and rut depth 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 slopes lower than 20% and those greater than 20%. Bulk density has become quite close to the critical value after 15 cycles. We observed soil rutting on the treatments started with 10 cycles. Soil disturbance increased significantly on slopes with less than 20% inclination with a dry bulk density of 1.157 g cm -3 after 5 cycles compared to 0.923 g cm -3 on slopes lower than 10%. In addition the litter ma...
International Journal of Forest Engineering, 2018
We quantified the effectiveness of different soil protective mat compositions (brush, sawdust, co... more We quantified the effectiveness of different soil protective mat compositions (brush, sawdust, combination of brush and sawdust) and densities (light density of 10 kg m−2 and heavy density of 20 kg m−2) on compaction and rutting on skid trails in mountainous forests following one, four, and 10 machine passes on two trail gradient classes (≤ 20% and > 20%). Soil bulk density and rut depth increased markedly with traffic frequency on both slope gradient classes on bare and protected soil, but soil protective mats delayed the onset of adverse soil responses and reduced the level of soil damage. Brush mats provided a more effective protection than sawdust and the combination of brush and sawdust and heavy density brush mats more so than light density mats. Compared to bare soil, heavy brush reinforcement significantly reduced bulk density for up to 10 passes on trail gradients ≤ 20% and four passes on gradients > 20%, regardless of soil protective mat composition. Light and heavy ...
Harvest traffic with heavy equipment causes damage to forest soils. Whereas increased soil damage... more 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...
The objective of this study was to compare forest soil bulk density values obtained through conve... more The objective of this study was to compare forest soil bulk density values obtained through conventional sampling methods such as the volumetric ring (VR: diameter 5 cm, length 10 cm) and paraffin sealed clod (PSC), with a variation of the VR, where rectangular boxes (RB) of four different dimensions were used. Sampling transects were established on a machine operating trail located in a beech (Fagus orientalis Lipsky) stand in Northern Iran. At each transect, three soil samples were collected at three different locations. Samples from different methods were spaced by a 50 cm distance to avoid direct interactions. The soil class of our study area was Combisols according to the WRB classification with a clay texture. Soil bulk density differed significantly between the three sampling methods. The lowest values were obtained with the RB (average 1.25 g cm), followed by the VR (average 1.40 g cm), and lastly the PSC (average 1.52 g cm). The values obtained with four variations of the R...
JOJ Horticulture & Arboriculture, 2018
Geoderma
Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known... more Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0-10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire ground pressure. Three skidder types (rubber tired "Timberjack 450C" skidder (site RT1), rubber tired "TAF E655" skidder (site RT2), "Onezhets 110" crawler skidder (site CS)), two levels of trail gradient (≤20% and > 20%), four levels of traffic frequency (4, 8, 15, and 40 passes), and four distances of buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of the skid trail edges were analyzed. Results showed that topsoil bulk density increased with greater traffic intensity for all skidder types and on both slopes. With increasing traffic intensities topsoil physical properties gradually deteriorated in zones that were further from the skid trail margin. While this process occurred faster on steeper slopes (i.e., fewer passes were required), the pattern was consistent for all three machine types. Consequently, the area adversely affected by skidding machines increased with increasing harvest traffic, with soil conditions within the first 0.5 to 1 m along the skid trail margin more similar to the skid trail itself and the conditions > 1 m more similar to untrafficked areas. The significant effect of skid trail slope gradient on increased soil disturbance provides land managers with important information for designing skid trail systems that protect soil physical properties to maintain overall site productivity. The adverse effects of the extent and degree of soil disturbance can be controlled by operation constraints that include reducing tire pressure to the minimum allowable weight, installing larger diameter tires to increase the length of the machine footprint, increasing the number of axles or decreasing the number of equipment passes.