Extent Of Soil Disturbance Research Articles

Impact on Soil Physical Properties Related to a High Mechanization Level in the Row Thinning of a Korean Pine Stand

In ground-based harvesting, machine traffic can cause soil physical disturbances including excessive compaction, the displacement of the soil surface and topsoil, and rutting. These impacts can indirectly hamper seedling survival and tree growth because of reduced soil permeability and root growth. However, the extent of soil disturbance in mechanized row thinning by harvester and forwarder systems in South Korea is unclear. Therefore, our objectives were to determine the impacts of two types of harvesters, soil textures, and extraction methods on soil compaction and rutting in a Korean Pine stand. The results showed that the machine passes affected soil disturbances. The soil bulk density inside the tracks (at 0–10 and 10–20 cm soil depths) after harvester passes (wheeled vs. tracked) increased by 17 and 27% and 30 and 20%, respectively. The largest impact was recorded for the forwarding track and significant differences were observed between the track and reference locations. Furthermore, the rutting depth in the forwarding trails was significantly higher than in the harvester trails. Thus, the application of a brush mat on harvester and forwarder trails may reduce machine-induced soil compaction. These results provide useful information to help forest engineers and field managers design environmentally sound ground-based harvesting operations.

Effects of long-term grazed crop and pasture systems under no-till on organic matter fractions and selected quality parameters of soil in the Overberg, South Africa

There is limited soil research on semi-arid, grazed no-till crop and pasture systems. The long-term (10 years) effect of three grazed no-till dryland crop and pasture rotation systems, and perennial lucerne pasture were assessed on soil carbon (C) and nitrogen (N) stocks, soil organic matter functional pools and selected soil quality parameters in the Overberg, South Africa. The largest soil C and N stocks (0–30 cm) were found in crop–pasture systems containing wheat and medic/clover (70.2–74.9 Mg C ha−1 and 8.3–8.4 Mg N ha−1), compared with perennial lucerne pasture (63.4 Mg C ha−1 and 7.7 Mg N ha−1) or cropping-only systems (54.7–58.9 Mg C ha−1 and 6.3–6.7 Mg N ha−1). Significantly higher labile C and N (free particulate organic matter fraction) contents were observed in crop–pasture systems (1.37–1.74 g C kg−1 and 0.107–0.110 g N kg−1) than in continuous cropping systems (0.9–1.0 g C kg−1 and 0.042–0.045 g N kg−1), attributed to higher annual C and N inputs and lower extent of soil disturbance. Significant positive correlations were found between soil C and N functional pools and soil quality parameters (soil respiration, effective cation exchange capacity and aggregate stability) and wheat yields. The results show the importance of the medic/clover pasture and wheat rotations in enhancing soil quality in the Overberg region.

An operational UAV-based approach for stand-level assessment of soil disturbance after forest harvesting

ABSTRACTThe effectiveness of generating virtual transects on unmanned aerial vehicle-derived orthomosaics was evaluated in estimating the extent of soil disturbance by severity class. Combinations of 4 transect lengths (5–50 m) and five sampling intensities (1–20 transects per ha) were used in assessing traffic intensity and the severity of soil disturbance on six post-harvest, cut-to-length (CTL) clearfell sites. In total, 15% of the 33 ha studied showed some trace of vehicle traffic. Of this, 63% of was categorized as light (no visible surface disturbance). Traffic intensity varied from 787 to 1256 m ha−1, with a weighted mean of 956 m ha−1, approximately twice the geometrical minimum achievable with CTL technology under perfect conditions. An overall weighted mean of 4.7% of the total site area was compromised by severe rutting. A high sampling intensity, increasing with decreasing incidence of soil disturbance, is required if mean estimation error is to be kept below 20%. The paper presents a methodology that can be generally applied in forest management or in similar land-use evaluations.

Assessment of ground-based skidding impacts on the horizontally rate and extent of soil disturbance along the margin of the skid trail

Skidding operations significantly influenced soil physical properties up to a 2-m distance from the wheel ruts in a forest ecosystem. The most significant changes in soil properties were identified within a 0.5 m to 1 m transitional zone. The main purpose of this investigation was to determine how far into a forest stand changes in soil physical properties were evident due to skidding operations. Treatment plots with three replications included combinations of four distance zones at 0.5 m intervals (0 to 2 m in distance) on both sides of skid trail edges to the forest, three slope gradient levels were applied (gentle 20 %) and two levels of traffic intensities 20 and 40 passes (with a rubber-tyred skidder, model HSM 904). A total of 576 soil samples were used in this study. Results showed that the physical properties of soil were significantly changed by each traffic intensity in the first distance zone, where the slope was >20 % compared to soil changes at a slope of 20 % after 20 and 40 skidding cycles. Dry bulk density values reached its maximum levels in the first 0.5 m from the skid trail on slopes >20 % after 40 skidding cycles.

Soil respiration after tillage under different fertiliser treatments – implications for modelling and balancing

Temperature-driven models of soil respiration (SR) are crucial for estimating C-balances of arable soils. However, model construction may be severely influenced by tillage operations. The impact of tillage on the temperature dependence of SR was studied to reveal the temporal patterns of model quality of temperature-driven SR-models. To obtain SR, CO2 fluxes were measured with a dynamic chamber technique in treatments of an energy crop rotation amended with biogas residues (BR) and mineral fertiliser (MF). Measurements were performed with short intervals during the first three days after tillage operations, then with extending intervals between measurements up to 35 days after tillage. Additionally, soil concentrations of hot-water extractable organic carbon (HWC) were determined before and during the experiment. Overall, in all treatments individual CO2 fluxes were affected by the extent of soil disturbance and fertiliser treatment. The highest tillage-induced fluxes where observed after disking in MF treatment. Tillage also induced an immediate increase of HWC, indicating additional labile C and a fast response of microbial activity. However, the change of HWC lasted only one day and approximated the pre-tillage values within a week. Even though BR soil had a higher HWC content, the increased C mineralisation in one repetition of MF suggests that buried plant residues might have a higher influence on SR after tillage than the type of fertiliser. Directly after soil disturbance by tillage it was impossible to construct temperature-driven models for SR in all treatments. Assuming that the coefficient of determination is appropriate with R2≥0.5 and the model quality is good with NRMSE≤0.15, the qualities of the models increased continuously with time, but were unsatisfying for at least two weeks. During this time, SR showed a high sensitivity to changing environmental influences like precipitation and soil moisture or available C for microbial turnover, rather than temperature. The treatment BR showed a less sensitive pattern, which might be attributed to an altered soil structure and microbial activity of soil after long-term application of an organic fertiliser like BR. Therefore, temperature-driven models for the prediction of soil derived CO2 emissions should be applied carefully for the days and weeks after tillage and verification by measurements in shorter intervals is advisable.

Soil disturbance in integrated logging operations and the potential impacts on a fossorial Australian frog

Forestry practices have been shown to impact on amphibian species to varying degrees. Burrowing amphibian species may be of less concern as they may be able to escape the direct impacts of a logging operation. The giant burrowing frog Heleioporus australiacus is a threatened frog species in south-eastern Australia. Logging is currently excluded from known habitat of this species. We examine aerial photographs to determine the extent of soil disturbance in 15 coupes in which integrated logging has occurred and 15 unlogged coupes. We then examine the extent of soil disturbance in a standard operation in a simple field experiment to assess the potential for a logging operation to affect H. australiacus . Approximately 65% of a coupe experiences medium to high levels of soil disturbance during an integrated logging operation. These disturbances appear to be at a level which would be disruptive to an individual H. australiacus occupying such sites. Alternate logging practices result in varying levels of disturbance and therefore are likely to have varying impacts on individuals. Active management of an area following a logging operation may improve the habitat for H. australiacus and other soil organisms.

Evaluation of an Adaptive Suspension Vehicle

The Adaptive Suspension Vehicle, a proof-of-concept, six-legged robotic walking machine, was subject to a series of field trials to evaluate the maneuverability and trafficability characteristics of walking machines. Maneuverability trials were structured to test performance as a carrier for frame-mounted feller-buncher heads in both thinning and clearcutting applications. The trafficability trials focused on the type and extent of soil disturbance, especially changes in soil bulk density, mechanical resistance, macro- and micro-porosity, the machine was found to impact the soil very differently than wheeled or tracked equipment. Direct comparisons of soil parameters were limited because of time and budget restrictions but seem to indicate that the legged locomotion offered distinct production and soil disturbance advantages, especially on steep slopes and in wetlands.

Logging and soil disturbance in southeast British Columbia

The purpose of this study was to document and to analyze extent, type, and degree of soil disturbance on ground-skidded and cable-yarded cutovers. The primary hypothesis was that ground skidding on steep, high elevation sites generates more soil disturbance than cable yarding. Thirty-one cutovers were surveyed in the Nelson Forest Region: 25 logged by ground skidding and 6 by cable yarding. Three replications were obtained for each season – slope class on ground-skidded sites. Cable-logged areas were also replicated three times, but only for season. Elevations of the cutovers ranged from 910 to 1970 m with an average of 1360 m. Slope steepness on cutovers ranged from 5 to 74%. Soil disturbance was significantly greater on ground-skidded than on cable-yarded cutovers, averaging 40–45% vs. 22–30%, respectively, regardless of season. Differences in soil disturbance between logging methods by season were small and not significant. Average soil disturbances for summer cable yarding and ground skidding were 30 and 45%, respectively, compared with 22 and 40% for winter operations. Analysis of soil disturbance by source revealed skidroads as the major cause of disturbance on ground-skidded cutovers, regardless of season. The primary source of disturbance on cable-yarded areas was yarding in the summer and haul roads in the winter. Ground skidding also caused more deep to very deep disturbance, averaging 30% in winter and 35% in summer compared with 18 and 14% on cable-yarded sites. For both methods deep and very deep disturbance were most common accounting for 75–80% of total disturbance. Extent of soil disturbance and slope steepness were not significantly related. The high variability in soil disturbance noted in this study was similar to other surveys. Most studies have attempted to associate such variation with major environmental factors but with little success. To fully explain soil disturbance, operational factors such as planning and layout of logging must be considered.

Embedded Anchor Response to uplift Loading

A number of factors which influence soil-anchor interaction are evaluated, and in addition, the extent of soil disturbance and the influence of pore water pressures during testing are assessed. Response under repeated and sustained-repeated loading is shown to be represented by a family of hyperbolic curves, and a failure criterion is determined by the critical strain condition below which a satisfactory response can still be subsequent to repeated loading. A strain dependent mechanism is used for defining behaviour under varying loading conditions which permits an assessment of anchor life when subjected to a package of projectd environmental conditions. Where possible the results are compared to those of other workers in the anchor field, and recommendations made which may lead to a better understanding of embedded systems.