Purpose of Review
Lowering the impact of forest utilisation on the forest environment is a part of the improvement in sustainable forest management. As part of forest utilisation, timber harvesting ...can also cause environmental implications. The main impact of forest operations is on the soil, on regeneration and on the residual stand. The aim of the present review was to identify the state of the art in forest utilisation, identifying how and how much forest operations affect forest soil, regeneration and the remaining stand. Particular attention was paid to the level of impact and potential to limit this.
Recent Findings
There are a large number of publications tackling forest harvesting, but most of them do not give a comprehensive framework and they mainly focus on one or very few aspects of forest damage. In order to improve general knowledge of the impact of forest operations, it was proposed that the scope of recent findings should be examined and a compilation of the available results from different regions should be presented in one paper.
Summary
It was found that the least impactful machine-based forest operations were harvester–forwarder technologies, while a larger scale of damage could be expected from ground-based extraction systems (skidders) and cable yarders. Animal power, if applicable, tended to be very neutral to the forest environment. A decrease in damage is possible by optimising skid trail and strip road planning, careful completion of forest operations and training for operators. The existence of legal documents controlling post-harvesting stand damage are rare and have been implemented in only two countries; there is no post-harvesting control on soil damage and natural regeneration.
In permafrost regions, roads and soil slopes experience freeze–thaw cycles annually and the soil characteristics (such as strength and conductivity) change irreversibly. Several studies have been ...conducted on the evaluation of soil damage using soil mechanics principles and electrical measurements. Owing to the limitations of previous studies, such as low efficiency and the inapplicability of real-time testing for assessing damages, a real-time quantitative test method for assessing the damage degree of layered soil subjected to freeze–thaw cycles based on electrical measurements is proposed. An electrical measurement device was developed for testing the electrical parameters of multilayer soil. Combined with electrical measurements, freeze–thaw cycle tests were performed. The resistivity of each layer of soil under freeze–thaw cycles was determined. Additionally, microstructural parameters of the multilayered soil were determined through computed tomography to investigate the changes in the soil microstructure during freeze–thaw cycles. The porosity and pore distribution characteristics of the multilayered soil under freeze–thaw cycles were obtained using image processing methods, such as median filter and K-means clustering. As the number of freeze–thaw cycles increased, the soil porosity increased, and the pore structure became less complex. Based on the relationship between the soil resistivity and the microstructural parameters, the soil damage mechanism was described, and a damage factor was introduced in developing the model. Furthermore, the dynamic damage process of the multilayered soil under freeze–thaw cycles was evaluated using the damage model, and the settlement was used to verify the results. And the damage model can be applied to evaluate the damage state of soil in permafrost region
•The real time test method for resistivity of multi-layer soil is presented.•The temporal and spatial variation of resistivity of soil is obtained.•The dynamic damage model of soil is established by combining micro parameters with resistivity.•Damage state of soil is evaluated by resistivity test.
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.
Rutting measurements are a significant part of scientific research on the impact of forest vehicles on the forest soils and damage to the forest transport infrastructure. Although photogrammetric ...methods of measurement or measurements based on LiDAR (light detection and ranging) data are increasingly being used for rutting measurements, the previous research conducted using these methods indicated the challenge of recording water-filled ruts. For this reason, it is necessary to define a reliable method of rutting field measurement in lowland forest stands characterized by a high level of groundwater that fills the ruts shortly after the passage of forest vehicles. This research analyzed the measurement accuracy using a total station and a GNSS RTK device with a CROPOS correction base in relation to the measuring rod that represented the reference method. Based on recorded and processed data, ruts are displayed in two ways: as net and as gross value of rut depth. The analysis of net rutting revealed a statistically significant difference between the calculated rut depths based on measurements with a GNSS RTK device and other methods. On average, the net rutting measured by the GNSS RTK device was 2.86 cm smaller than that of the reference method. When calculating the gross rutting, which consisted of the net rut depth and the bulge height, no statistically significant difference was found between the measurement methods used. Based on this result, the bulge height was also analyzed, and showed a statistically significant difference between the data recorded by the GNSS RTK device and other methods. It can be concluded that measuring the depth of ruts with a total station gives accurate data and represents the optimal modern field measurement method for the same or similar terrain conditions. In contrast, the GNSS RTK device, which constantly gives higher elevation points, can be used to measure gross rutting.
Predictive factors for forwarder rut formation were studied on fine-grained mineral soils. The study was carried out in southern Finland in mid-May, when the soil water contents were high after ...snowmelt. A total of 7 study tracks of 20 m were cut with a harvester. After removing the logging residues, a loaded forwarder made 3-4 passes on each track. The forwarder rut depth was related to the total overdriven mass driven over the measurement line, volumetric water content, cone penetration resistance and the harvester rut depth. A total of five mixed-effects models are presented to predict the rut depth. The first model includes the overdriven cumulative mass, volumetric water content of the soil and the cone penetration resistance. As a penetrometer is more of a research tool, the second model includes only the overdriven cumulative mass and water content, factors that can be used in practical planning operations. The remaining three models all include the rut depth after the harvester pass and the overdriven cumulative mass and also include volumetric water content and cone penetration resistance. The model including the rut depth after a harvester pass and the overdriven cumulative mass is a good predictor of the rut depth and supports earlier findings on the connection between harvester and forwarder rut formations.
The excessive use of cultivated land for non-grain production activities is considered a threat to grain security. This study presents an analysis framework on unraveling the causal mechanisms for ...non-grain production of cultivated land. We apply the analysis framework in Liyang, which is located in the Yangtze River Delta and is also an important “national grain base” county of China. We first determine four non-grain production categories as immediately recoverable (IMR), simple-engineering recoverable (SER), engineering recoverable (ENR), and irrecoverable (IR) based on the effect of non-grain activities on the degree of soil damage of the cultivated land, especially the difficulty of restoring the capacity for grain production. Then, we analyze the spatial pattern features for non-grain production of four given categories at the village scale. Furthermore, we reveal the mechanisms of the four categories using multiple linear regression modeling with geophysical, demographic, economic, and policy variables. The results show that the total non-grain area of cultivated land in Liyang is 28,158.38 hectares, and the non-grain rate is 48.09%, ranging from 10.59% to 96.75% among villages. The IMR, SER, ER, and IR rates are 11.81%, 17.76%, 15.07%, and 3.45%, respectively. There is also a significant neighborhood effect among the four categories, indicating that non-grain production activities have a stimulating effect on the surrounding operators of cultivated land. Farming conditions such as the proportion of irrigated farmland and economic variables such as the tourism scale have stronger effects on non-grain production than demographic variables. Policy variables, especially the cultivated land transfer policy, neither inhibit nor promote non-grain production. Based on these findings, we make policy suggestions for reducing non-grain production activities and protecting cultivated land. This analysis framework contributes to a new perspective for unraveling the causal mechanisms and making categorical governance decisions of non-grain production on cultivated land at the village level.
3D dynamic interaction of two adjacent elastic foundations embedded in a finite layered soil region rested in a homogeneous elastic isotropic half‐space with a transient dynamic source is studied. ...The hybrid computational model, the corresponding numerical scheme and the accompanied software are developed, verified and inserted in detail parametric study. The hybrid approach is based on (a) finite element method (FEM) describing the scattered wave field in a finite layered soil profile with two foundations; (b) boundary element method (BEM) considering waves radiating from a dynamic transient source in elastic semi‐infinite range. The aim is to propose an efficient hybrid methodology for evaluation of the dynamic response of a foundation‐soil‐foundation system, taking into account (a) the whole wave path from the dynamic source, through the layered soil region, till the underground structures; (b) the damage state of the geological material. The BEM model is based on the 3D elastodynamic fundamental solution in Fourier domain and it is applied in order to obtain frequency‐dependent stiffness matrix and load vector of the dynamically active semi‐infinite geological zone. Once the BEM model is formulated, it is inserted as a macro‐finite element in the FEM software package ABAQUS. The frequency‐dependent FEM model describing the wave field in finite layered soil profile with two elastic foundations is realized by ABAQUS. Solutions in time domain are obtained through application of the inverse fast Fourier transform. As a final result an efficient hybrid model comprising all in one: dynamic (seismic or other type) source‐homogeneous elastic half‐space‐finite heterogeneous by layers and foundations soil profile, is presented. Parametric study illustrating the sensitivity of the dynamic field to key factors such as the type and properties of the load, the soil layering, the material properties of the far‐ and near‐field soil regions, the damaged state of the geological material and the foundation‐soil‐foundation interaction is shown and discussed.
3D dynamic interaction of two adjacent elastic foundations embedded in a finite layered soil region rested in a homogeneous elastic isotropic half‐space with a transient dynamic source is studied. The hybrid computational model, the corresponding numerical scheme and the accompanied software are developed, verified and inserted in detail parametric study. The hybrid approach is based on (a) finite element method (FEM) describing the scattered wave field in a finite layered soil profile with two foundations; (b) boundary element method (BEM) considering waves radiating from a dynamic transient source in elastic semi‐infinite range.…
The composite bucket shallow foundation proposed by Tianjin University can be better adapted to the soft geological conditions in China for offshore wind engineering. The offshore wind turbines are ...generally subjected to relatively large horizontal load induced by waves, currents and ice loading. Therefore, calculating the horizontal bearing capacity is an important part of the design for the composite bucket shallow foundation. In this paper, according to the numerical simulation, considering the constraint of bucket foundation on internal soil in different degrees firstly, the horizontal soil damage rate is introduced into the formula as a new empirical parameter Next, upper-bound solution of the horizontal bearing capacity of a composite bucket shallow foundation is derived in sand. Fianally, the calculation method is validated by the bucket model tests with different height-diameter ratios in sand under horizontal loading.
Purpose
Intensive livestock grazing has been associated with an increased risk of soil erosion and concomitant negative impacts on the ecological status of watercourses. Whilst various mitigation ...options are promoted for reducing livestock impacts, there is a paucity of data on the relationship between stocking rates and quantified sediment losses. This evidence gap means there is uncertainty regarding the cost–benefit of policy preferred best management.
Methods
Sediment yields from 15 hydrologically isolated field scale catchments on a heavily instrumented ruminant livestock farm in the south west UK were investigated over ~ 26 months spread across 6 years. Sediment yields were compared to cattle and sheep stocking rates on long-term, winter (November–April), and monthly timescales. The impacts of livestock on soil vegetation cover and bulk density were also examined. Cattle were tracked using GPS collars to determine how grazing related to soil damage.
Results
No observable impact of livestock stocking rates of 0.15–1.00 UK livestock units (LU) ha
−1
for sheep, and 0–0.77 LU ha
−1
for cattle on sediment yields was observed at any of the three timescales. Cattle preferentially spent time close to specific fences where soils were visually damaged. However, there was no indication that livestock have a significant effect on soil bulk density on a field scale. Livestock were housed indoors during winters when most rainfall occurs, and best management practices were used which when combined with low erodibility clayey soils likely limited sediment losses.
Conclusion
A combination of clayey soils and soil trampling in only a small proportion of the field areas lead to little impact from grazing livestock. Within similar landscapes with best practice livestock grazing management, additional targeted measures to reduce erosion are unlikely to yield a significant cost-benefit.
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