Skid Trails Research Articles

Residual Stand Damage Due to Timber Harvesting in PT Tunas Timber Lestari, Papua

Timber harvesting activities can cause damage to residual stands, this can occur due to improper timber harvesting techniques. The study was conducted at one of PT Tunas Timber Lestari’s IUPHHK-HA in Papua Province. The results showed that: 1). The number of trees felled and skidded on 3 logging compartment with each of the 3 plot of observation sample has an area of 2 ha (the total area of the research is 18 ha) is 16 trees on average; 2). The average number of residual stand (trees with a diameter of ≥ 20 cm) damaged by logging is 26 trees (13.00%) per ha with details of damage to canopy of 4 trees (15.39%), broken branches of 13 trees (50.00%), the trunk wound of 2 trees (7.69%) and the collapsed/tilted of 7 trees (26.92%); 3). Damage to the residual stand in felling is caused more by the lack of skilled chainsaw operators in determining felling direction; 4) Damage to residual stands due to skidding is an average of 23 trees (9.99%) per ha, with details of 1 trees buttress (4.4%), wounds injuries of 7 trees steam (2.97) and collapsed/slanted 15 trees (65.2%); and 5). The cause of damage to the residual stand on skidding is that the skid trail has not been made and the skid tractor maneuvers too often.

Effects of biopore infiltration holes and cross drain on soil properties on skidding roads and natural production forest

Logging activities in natural production forests tend to have negative impacts on soil quality. This study aims to examine the effect of biopore infiltration holes and cross drains on the chemical and physical properties of the soil both on skid trails and in natural forests. The study was conducted at a natural production forest in West Kalimantan. The results showed that there was no significant change in the chemical properties of the soil in both the skid trails and natural forest, except for the higher organic C parameter in the natural forest. There was an increase in organic C from 1.16% to 2.04% (<3%) on the skid trails before and after one year. In general, there was a change in the physical properties of the soil on the skid trails. In the natural forest, the bulk density is lower than that on the skid trails and tends to increase with soil depth. Porosity in the center of the skid trails decreases by 24% compared to that in the natural forests at a depth of 0-10 cm. The phenomenon of degradation is also apparent in the parameters of available water, soil permeability, and drainage pores in the middle of the skid trails.

Long-Term Seeding Outcomes in Slash Piles and Skid Trails after Conifer Removal

Conifer removal in interior woodland ecosystems of the western US is a common management treatment used to decrease fire hazard and shift woodlands to more historical states. Woody material is frequently removed by skidding material off site and via slash pile burning. Assessing the long-term outcomes of seeding treatments after such ground disturbing activities is critical for informing future management and treatment strategies. Using two designed experiments from a central Oregon juniper woodland, we resampled slash piles and skid trails 8 years after seeding. Our objectives were to assess the long-term vegetation response to conifer removal, ground disturbance, and seeding source (cultivar and local) in slash piles and skid trails. We found that seeded species persisted in the long term, but abundance patterns depended on the species, seed source, and the type of disturbance. In general, there were more robust patterns of persistence after pile burning compared to skid trails. Seeding also suppressed exotic grass cover in the long term, particularly for the local seed source. However, the invasion levels we report are still problematic and may have impacts on biodiversity, forage and fire behavior. Our short-term results were not predictive of longer-term outcomes, but short- and long-term patterns were somewhat predictable based on species life history traits and ecological succession. The use of a mix of species with different life history traits may contribute to seeding success in terms of exotic grass suppression. Lastly, our results suggest that locally adapted seed sources may perform as well or better compared to cultivars. However, more aggressive weed treatments before and after conifer removal activities and wider seeding application may be needed to effectively treat exotic grass populations.

Effects of Skidding Operations after Tree Harvesting and Soil Scarification by Felled Trees on Initial Seedling Emergence of Spanish Black Pine (Pinus nigra Arn. ssp. salzmannii)

Skidding operations are thought to have negative impacts on soil emergence because they may increase soil compaction and reduce vegetation cover and the soil’s organic matter content. We investigated whether and to what extent tree harvesting and subsequent skidding initially altered seedling emergence in two Mediterranean forests of Pinus nigra Arn. ssp. salzmannii (Spanish black pine) in the Cuenca Mountains (Spain). Our main objective was to compare the Spanish black pine seedling emergence rate among skid trails, soil areas scarified by felled trees, and areas undisturbed next to harvest operations. In addition, we selected an unmanaged stand as reference, in order to look for evidence of seedling emergence under natural conditions. We measured Spanish black pine seed fall and seedling emergence immediately after harvest operations in two locations in the Cuenca Mountains (Palancares and Majadas forests), which are typical forests in Cuenca Mountains. The results showed that the Palancares site presented higher seed fall in comparison to the Majadas site. In addition, seed fall was higher in the unmanaged stand, as we recorded a higher tree density in this site in comparison to harvested stands (Palancares and Majadas). Furthermore, our results demonstrated differences in seedling emergence between lower elevation drier Palancares and higher elevation wetter Majadas and relative differences in seedling emergence among skid trail, scarified, and undisturbed harvested areas. Finally, the unmanaged stand presented the highest seedling emergence in comparison to scarified, compacted, and non-disturbed harvested areas. Overall, the results suggest a short-term impact of skidding on seedling emergence, which should be considered for future management guidelines of Spanish black pine in the Mediterranean climate.

General Productivity Predicting Model for Skidder Working in Eucalypt Plantations

Timber extraction from forest to the roadside/landing can be operated using cut-to-length, whole stem and whole tree. Skidding is one of the options for wood extraction. This paper aimed to review the available studies on work productivity of skidders in Eucalypt plantations. Reviewing the machine productivity information indicated that skidding productivity in Eucalypt plantations may be impacted by tree volume, load size, skid distance, slope of skid trail and power of the machine. Based on the reviewed literatures the machine productivity varied from 11.20 green tons per PMH0 (Caterpillar 528 operating in skidding distance of 251 m tested in USA) to 80.25 green tons per PMH0 (Timberjack 1710D operating in skidding distance of 241 m in Brazil). General productivity model was developed including variables such as skidding distance, tree size and power of machine. Future research could verify the impact of harvesting intensity/yield per ha, plantation layout (landing locations and block shape), operator experience, terrain conditions and availability of chippers/or processors at the landing in the case of hot decking on the productivity of the skidders in Eucalypt plantations.

Особливості техногенного впливу лісокористування на чистоту води у гірських лісових водотоках

Під час здійснення лісозаготівель у гірських умовах із застосуванням наземного транспортування деревини відбувається трансформація лісового ґрунту як у межах лісосіки, так і на трелювальних волоках. Трелювальні волоки, по яких заготовлена деревини доставляється до навантажувальних майданчиків, прокладаються на схилах різної стрімкості, що спричиняє порушення монолітної структури ґрунту та утворення значних обсягів експлуатаційної ерозії. Внаслідок багаторазового проїзду лісових машин по волоках формуються глибокі колії, по яких відбувається поверхневий стік води до підніжжя схилу, яка потрапляє у водотоки. Тому волоки одночасно є і руслами стоку води, яка концентрується на них у разі виникнення інтенсивних опадів та внаслідок cніготанення. При цьому разом із водою виносяться і частинки лісового ґрунту, що призводить до забруднення води.&#x0D; Дослідженнями зарубіжних і вітчизняних науковців встановлено, що основним потенційним впливом на чистоту води внаслідок лісогосподарської діяльності є потрапляння у річки частинок землі з доріг і трелювальних волоків. Тому одним із важливих завдань є встановлення ступеня впливу техногенних чинників, які виникають під час лісокористування, на ступінь забруднення води в лісових водотоках. З огляду на це, були здійснені чотирирічні дослідження на двох лісових водозборах з метою вивчення ступеня каламутності води в руслах рік. У результаті дослідження встановлено чітку тенденцію щодо збільшення каламутності води в робочі дні (понеділок-п’ятниця) та її суттєве зменшення під час не робочих днів (субота, неділя). При цьому характерним є зростання забруднення води, починаючи з вранішніх годин з поступовим його зменшенням наприкінці робочого дня.

Influence of Timber Harvesting Operations and Streamside Management Zone Effectiveness on Sediment Delivery to Headwater Streams in Appalachia

Disturbances created by timber harvesting equipment and associated haul roads and skid trails can create overland sediment flows (sediment paths), especially in steeply sloping terrain, leading to stream sedimentation. This study investigated the effect of variables associated with GPS tracked harvest equipment movement, skid trail development and retirement, topography, and streamside management zone (SMZ) width and tree retention on sediment delivery to streams. While the intensity of harvest equipment traffic was not correlated with sediment path development, the presence and location of skid trails were. All of the sediment paths were found to originate at water control structures, influenced by microtopographic features, on the skid trails directly adjacent to SMZs. Mesic slopes were associated with increased sediment path development across all SMZ configurations. Two factors, the accumulation of coarse logging debris in the SMZ and the increased distance of skid trails to streams, were both correlated with decreased sediment path development. The study provides insight into how these variables interact and can be used to develop site-specific guidelines for SMZs in steeply sloping terrain that could improve their efficiency and effectiveness.

Soil impacts and residual stand damage from thinning operations

ABSTRACT Thinning has a crucial role in retaining the future value of stands; hence, excessive soil disturbance and damage to residual trees can diminish thinning advantages. The research aims were to assess soil disturbance and the level of stand damage from thinning operations. Thinning intensity ranged from 8.3% to 19.1% of the standing volume. Soil disturbance and damage level to residual trees, were determined in five young even-aged hardwood stands, using ground-based extraction systems. Tree felling was done by chainsaw, and full trees were extracted by a skidder. Point-transect method and systematic sampling plots were used to characterize soil disturbance and residual trees damage, respectively. Surface of disturbed soil ranged from 14% to 27% and stand damage ranged from 5% to 18% of the residual trees and they were significantly increased by increasing thinning intensity. Soil resistance to penetration at a depth of 0–10 cm in the shallow disturbed (0.39 MPa), deep disturbed (0.52 MPa), and skid trails (0.79 MPa) were increased by 14%, 27%, and 54%, respectively, compared to the undisturbed soils (0.25 MPa). Winching was the main cause of soil disturbance and damage to residual trees. The highest frequency of damage was observed on trees with a dbh class of 20 cm (24.3%). Most of the stand damage occurred on the bole (55%) of trees, with wound sizes ranging from 50 to 350 cm2, and most of the wounds (53%) showed damage to the cambium and wood fibers, at heights of <1 m above the ground line (76%).

Effectiveness of Three Post-Harvest Rehabilitation Treatments for Runoff and Sediment Reduction on Skid Trails in the Hyrcanian Forests

Ground-based skidding operations can lead to soil compaction and displacement, which could cause negative effects on forest soil. Hence, some efforts such as forestry best management practices (BMPs) must be implemented in the prone area to mitigate these possible impacts. Several materials and treatments have been adopted to suppress these adverse effects by increasing the ground cover. However, the effects of mulch treatments on runoff and sediment yield are inconclusive with a diverse range of effectiveness. For these reasons, in this research mulch treatments were tested as to determine how the application of organic mulch amendments such as straw and leaf litter and contour-felled logs would alleviate the runoff and sediment yield on machine operating trails and ensure successful hillslope stabilization. The aims of the study were to analyse and compare the effectiveness of leaf litter (LM) and straw mulch (SM) rate and different distances of contour-felled logs (CFL) to mitigate the runoff and sediment yield, and examine the impact of rainfall intensity on effectiveness of litter mulch, straw mulch, and contour-felled logs. Totally, 30 bounded runoff plots in the machine operating trails and four treatments including litter mulch (LMR1: 0.62, LMR2: 1.24, and LMR3: 1.86 kg m-2), straw mulch (SMR1: 0.45, SMR2: 0.92, and SMR3: 1.34 kg m-2), contour-felled logs (CFL10: 10, CFL20: 20, and CFL30: 30 m), and untreated area were established in triplicate with 4 m width and 100 m length. During the study period, the runoff and sediment yield in the untreated trails (U) were 2.36 mm and 11.84 g m-2. Straw (from 41.5 to 60.6%) and litter mulch (from 38.1 to 55.1%), and contour-felled logs treatments (from 70.8 to 88.1%) significantly decreased the runoff, compared to U treatment. Results show that mulch treatments with three different levels of Litter Mulch Rate, LMR1, LMR2, and LMR3 decreased mean sediment by 46.6, 64.0 and 71.8%, in the treatments with three different levels of Straw Mulch Rate, SMR1, SMR2, and SMR3 decreased mean sediment by 42.9, 62.1, and 69.9%, and in the treatments with three different distances of Contour-Felled Logs, CFL10, CFL20, and CFL30 decreased mean sediment by 90.6, 94.7 and 88.3% comparing to U, respectively. The relationships of the runoff and sediment responses to increasing mulching rate of litter and straw followed as negative logarithmic curves, but the decreasing-increasing trends were observed in runoff and sediment yield as the distance between contour-felled logs increased from 10 to 30 m. Polynomial regression equations were developed for predicting the runoff and sediment yield as a function of the application rate of litter and straw mulch and the distance between contour-felled logs, and rainfall intensity. We concluded that contour-felled logs treatment was more effective than both litter and straw mulch to mitigate the runoff, runoff coefficient, and sediment yield on machine operating trails. As a management measure, it could be possible to propose that the contour-felled logs with a distance of 20 m be prescribed to protect the machine operating trails from the negative effects of surface waterflow.

Soil Recovery Assessment after Timber Harvesting Based on the Sustainable Forest Operation (SFO) Perspective in Iranian Temperate Forests

Minimizing the impact of timber harvesting on forest stands and soils is one of the main goals of sustainable forest operation (SFO). Thus, it is necessary to make an accurate assessment of forest operations on soil that is based on the SFO perspective. The present study was conducted according to SFO principles to investigate the time required for the natural recovery of soil after disturbance by skidding operations in some Iranian forests. The physical, chemical, and biological properties of soil found in abandoned skid trails from different time periods were compared with undisturbed forest soils. The soil bulk density, the penetration resistance, and the microporosity of a 25-year-old skid trail were 8.4–27.4% and 50.4% greater, and the total porosity, macroporosity, and soil moisture were 1.9–17.1% and 4.6% lower than the undisturbed area. In a 25-year-old skid trail, the values of pH, Electrical conductivity (EC), C, N, available P, K, Ca, and Mg, earthworm density, and biomass were lower than in the undisturbed area, and the C/N ratio value was higher than in the undisturbed area. High traffic intensity and slope classes of 20–30% in a three-year-old skid trail had the greatest impact on soil properties. In order to have sustainable timber production, SFO should be developed and soil recovery time should be reduced through post-harvest management operation.

Soil organic matter mobilization by re-compaction of old forest skid trails

Wood harvesting is restricted to a system of permanent skid trails in order to minimize the soil disturbance and damage. Therefore, it is not the compaction of previously undisturbed forest soil, but the re-compaction of already existing skid trails that is of practical relevance when investigating machinery-induced wood harvest effects on soil properties. This study investigated the effects of machinery-induced re-compaction on soil physical, chemical, and microbiological properties of an old skid trail in a spruce forest by wheeling 8 times with a maximum total load of 32.2 Mg, using a genuine old skid trail as a control. Re-compaction significantly increased the bulk density and reduced the porosity, whereas the soil organic carbon (SOC) and total nitrogen (N) contents were not significantly affected. However, re-compaction reduced the SOC/total N ratio by 10%, suggesting considerable SOC mineralization after re-compaction. K2SO4 extractable C contents were increased by 94% at 0–3 cm and 67% at 7–10 cm depth after re-compaction. This led to 20% and 90% increased microbial biomass C/soil organic C (MBC/SOC) ratios at 0–3 cm and at 7–10 cm depth, respectively. In contrast, the ergosterol/MBC ratio was significantly decreased by 10% at 0–3 cm and by about 30% at 7–10 cm depth by re-compaction, apparently due to the promotion of bacteria and mobilization of soil organic matter.

Effects of plot length and soil texture on runoff and sediment yield occurring on machine-trafficked soils in a mixed deciduous forest

Runoff decreased significantly in each soil texture group, as plot length increased (2–40 m), whereas sediment yield showed an increasing trend. Runoff and sediment yield were higher in the clayey soil than in the loamy soil texture. An important issue for decreasing the negative impact of ground-based skidding operations on the physical environment is the appropriate drainage of the surface flow away from the skid trail to decrease runoff and subsequent soil loss. Water diversion structures can be used to disperse the water from the trail to the stand but information on adequate spacing is lacking, especially when considering machine-trafficked forest soils. The objective of this study was to quantify the effects of plot length (2, 5, 10, 20, 30, and 40 m) and two soil texture types (clayey and loamy) on runoff and sediment yield in skid trails in a mixed deciduous forest in order to determine the ideal spacing between adjacent water diversion structures. Runoff and sediment yield were measured for 25 rainfall events occurring over a 6-month period. The Pearson correlation was applied to determine the relationship among runoff, sediment yield, selected soil properties, plot length, soil texture, and canopy cover. In each soil texture group, runoff and sediment were plotted with rainfall intensity and plot length by a Gaussian polynomial regression model. Results show that plot length and soil texture significantly affected the amount of runoff and sediment yield. Plot length was positively and significantly correlated with sediment yield and negatively correlated with runoff. The highest runoff was found on the plot length of 2 m under clay soil by 1.49 mm followed by plot length of 5 m with clay by 1.15 mm and plot length of 2 m with loamy soil by 1.03 mm. In both soil texture classes, the runoff decreased significantly, as plot length increased. Likewise, in each plot length tested, the values of runoff were higher in the clayey soil than in the loamy soil texture. Significantly higher values of sediment yield were found in the plot length of 40 m and 30 m under the clayey soil (8.63 g m−2 and 6.84 g m−2) followed by plot length of 40 m under loamy soil (6.15 g m−2). In each soil texture, sediment yield increased significantly, as plot length increased. Additionally, in each plot length, sediment yield was higher in the clayey soil than in the loamy soil texture. The results of this study can be applied to mitigate the environmental impacts of ground-based skidding operations on skid trails and to determine the optimal distance of water diversion structure.

Assessing the impacts of log extraction by typical small shovel logging system on soil physical and hydrological properties in the Republic of Korea.

Typical small shovel logging system, using manual felling and extraction by small crawler excavator with grapple and crawler carriers, is the predominant logging method in the Republic of Korea, due to the associated high productivity. The trails with ground pressure and one more passes of the shovel and carriers may lead to soil compaction. However, impacts of these bunching-extraction technologies on physical and hydrological properties of soils are not well known. The main objectives of this study were to: (1) determine the bulk density, porosity, and saturated hydraulic conductivity of soils in logging operation areas with three different disturbance types (i.e., undisturbed areas [UAs], bladed trails [BTs], and skid trails [STs]), and (2) compare soil compaction between these disturbance types. The most intense compaction occurred within BTs and STs, with increased bulk density and reduced porosity and hydraulic conductivity. Soil bulk density increased by 27–53% at all depths in BTs and STs compared to UAs, while porosity decreased by 23–49%. On average, saturated hydraulic conductivity at depths of 0–20 cm decreased from 337.5 mm h−1 to 30.5 mm h−1 in the most compacted sections of BTs and STs. Skid trails, which are characterized by trail construction and frequent vehicle movement, also caused greater impacts on soil compaction than BTs. This study provides useful insights to aid forest consultants and field managers in planning more environmentally sound mechanized logging operations.

Assessment of topsoil disturbance caused by different skidding machine types beyond the margins of the machine operating trail

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.

Forest stand susceptibility mapping during harvesting using logistic regression and boosted regression tree machine learning models

Economic and environmental consequences of harvesting operations are important in forestry because of the damages caused by tree felling and timber transportation. In this research, we analyzed forest stand damage susceptibility using GIS-based logistic regression (LR) and boosted regression tree (BRT) machine learning models for the Shourab Forests. These forests contain valuable stands of Hyrcanian forests in northern Iran that represent many of the plant covers, geographical, and forest management features of this ancient ecosystem. To this end, we applied traversed transect to cover the forest unit. This allowed us to sample any damaged residual tree intersected by the transect resulting in a dataset of 152 damaged trees in the study area. Of this dataset, we utilized 106 damaged trees for training purposes, while the remaining instances (46 damage locations) served as the verification dataset. We utilized eight input factors as stand damage conditioning variables to model damage susceptibility, including distance from the skid trails, distance from the road, forest density, type of forest, topographic position index (TPI), length of slope (LS), altitude, slope aspect, and slope degree. Using these predictive variables, we calculated damage susceptibility using LR and BRT machine learning models, and, subsequently, devised the outputs in ArcGIS to produce the final stand damage susceptibility maps. As the statistical evaluative criteria, we calculated the area under the curve (AUC) and Akaike Information Criterion (AIC) for the validation and training data sets. According to the validation results, the BRT model (AIC = −109.04; AUC = 0.91) strongly outperformed the LR model (AIC = 96.14; AUC = 0.77). According to the results, among the explanatory variables, the slope degree and slope length had more significant impact on the stand damage. Moreover, the susceptibility maps depicted that more than one-third of the forest area were surveyed in high and very high damage susceptibility classes. According to the results mentioned above, using machine learning technique is an inevitable approach in controlling and mitigating the damages caused by human interferences in natural ecosystems especially in mountain forests. Our findings revealed that the susceptibility maps produced by BRT are highly relevant and beneficial for planning forest harvest operations.

Impacts of Small-Scale Mechanized Logging Equipment on Soil Compaction in Forests

The present study focuses on assessing the effects of different numbers of skidders on soil compaction. To assess the skidding effects, four-wheeled small-scale logging equipment attached to an ATV (Automated Transfer Vehicle) was used. Skidding operations were carried out on undistributed forest corridor (20 × 3 m).To measure soil compaction, 11 measurement lines were used, spaced at 2-m intervals. A total of 33 measurement points were used to measure soil compaction. Soil compaction values were measured for different soil depths with 5 cm intervals in the 0–40 cm range as MpA. The results were evaluated for the skidding zone and the wheel zone. Prior to skidding, soil compactions at 0 cm (top soil) is almost 2.5–3 times lower than those at the other depths. The p values indicate that the numbers of passes and the compaction values belong to nonidentical groups. The Bonferroni method was used to determine whether the compaction values are similar. The Dunn test results demonstrate that there were statistically significant differences between the mean values of the number of passes up to the 60th pass. However, there are no statistically significant differences between the means of the compaction values occurring between 60 and 80 and 100 and 120 passes. Generally, soil compaction is expressed as an increase in the soil bulk density. Soil bulk density and soil porosity are negatively correlated. It was found that for each of the zones, soil compaction values between the depths of 15 cm and 40 cm are approximately 4 times higher than at the 0 cm soil depth. Soil compaction values increased 3 times at the depths of between 0 cm and 5 cm. The average soil compactions values in the skidding zone are approximately 1.5 times higher than those at the wheel zones at the depth greater than 5 cm. The use of different skid trails will decrease soil compaction of the forest stand, provide uniformity of soil compactions in forest stand.

Fitocenološka združba kot kazalnik občutljivosti gozdnih tal za vožnjo gozdarske mehanizacije

In the article we determine the suitability of the phytocenose as a basic unit for determining soil susceptibility to mechanized logging. A total of 90 measurements of skid trail profiles were taken on a 13.9 km long sample transect. The forest infrastructure studied was categorized into primary and secondary skid trails, trails intended for CTL harvesting and undocumented trails. The following indicators were determined on the profiles: tyre track depth, trail width, trail slope, amount of rock present, presence of roots and road category. The deepest ruts were found in Blechno-Fagetum (6.9 cm), followed by Galio rotundifolii-Abietetum (6.4 cm) and Hacquetio-Fagetum (5.6 cm), while the shallowest ruts were found in Omphalodo-Fagetum (5.3 cm). The deepest ruts were found on primary skid trails (7.0 cm), followed by secondary skid trails (5.8 cm), while the shallowest ruts were found on skid trails used by CTL technology and on undocumented trails (1.9 cm). No significant difference in track depth was found between the four individual phytosociological units, but more extensive research should be conducted in the future.

Plot-Scale Effects of Ground-Based Skidding on Runoff and Soil Loss in Relation to Slopes and Leaf-On and Leaf-Off Periods in the Mixed Broadleaf Forests

Soil compaction and loss of surface litter from skid trails reduced the water absorption capacity in mineral soils, which reduced water infiltration and increased runoff, which then caused surface erosion. We hypothesized that ground-based skidding, different slope angle classes (0–20% and 20–40%), and forest canopy cover (leaf-on and leaf-off period) would be significantly effect on runoff and sediment loss. In order to measure the total runoff and the sediment loss, quadruplicate bounded runoff plot (2 m2) was established on the skidding and the control sites, and two different slope angle classes on each site (totally 16 runoff plots with 20 rainfall events) in the Gorazbon district in Hyrcanian deciduous forests following Timberjack 450C skidding operations (32 machine passes) over one-year. The natural rainfalls were measured due to get more useful data. The skidding and the leaf-on and leaf-off period had statistically significant effects on runoff and sediments (P &amp;lt; 0.05). There was a statistically significant difference between runoff and sediment loss in different leaf-on and leaf-off periods, with leaf-off period having the highest sediment loss, while the leaf-on period had the least. The slope angle classes and its interactions had no significant effect on runoff and sediment loss. The highest runoff of just over 1.6 mm was from a skid trail with a 20–40% slope in the leaf-off period, and the highest sediment production was 6.95 g in the skid trail with a 20–40% slope in the leaf-off period. In the Hyrcanian deciduous forest, fallen leaves (leaf-off period) were coincided with the highest and most erosive rainfall, which resulted in an increase in runoff and sediment yield.

An Assessment of Soil Compaction after Logging Operations in Central Amazonia

AbstractIn the forests of the Amazon Basin, there are still few studies on soil compaction caused by logging activities. This study evaluated an operation located on the property of a timber company in Central Amazonia, which uses harvesting techniques based on the harvesting system developed by the Centre for Agricultural Research in Suriname. The timber-extraction method employed by the timber company consists of three activities: (1) skid trail construction with a track-type tractor, (2) log winching with a winch attached to the tractor, and (3) log skidding with a rubber-tired skidder. Soil bulk density and soil penetration resistance were quantified to 20 cm in depth. After a single tractor ingress and egress for trail construction, the soil incurred an increased root growth-limiting bulk density and penetration resistance. However, log winching did not cause significant soil compaction. The conclusions of the study were: (1) the greatest impact from this harvesting system came from the skid trail construction, (2) the technique of log winching limited forest floor compaction and disturbance that damages forest regeneration, and (3) log skidding during dry soil conditions limited increases in compaction and track formation.

Post-Harvest Evaluation of Soil Physical Properties and Natural Regeneration Growth in Steep-Slope Terrains

Protection of forest soils during harvesting operations is necessary to reduce damage and accelerate recovery time. The current study aims to evaluate soil physical properties, natural regeneration, and its recovery process in treatments including slope gradient, traffic intensity and skid trail after long periods of time, after ceasing the timber harvesting operations. The most recent skidding operations within each 5 years recovery period were studied for a chronosequence of 20 years. Soil samples were taken in abandoned skid trails and data were recorded on naturally regenerated species and density. The results revealed that most soil disturbances occurred on the slopes &gt;20%, as well as the highest levels of traffic intensity. Bulk density and penetration resistance were still higher than the control area, with a significant difference between them, while total porosity was partially recovered. Twenty years after the skidding operation, soil bulk density and penetration resistance were 13.2% and 23.7% higher than the control area, while total porosity was 9.78% lower the than value of the control area. Seedlings of 50–150 cm and &gt;150 cm in height on skid trails had significantly lower density than those in the control. The number of seedlings per m2 was less than the control area in all skid trails and for all height classes. The proportion of seedlings present in low traffic intensity was higher than in medium and high traffic intensities. The findings confirmed that full recovery rates are lengthy, and more time than 20 years is required to fully recover, especially with regards to penetration resistance.