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A study was conducted to investigate the impacts of converting rubber plantations into oil palm plantations on soil properties and soil hydrology. Soil organic carbon (SOC), bulk density (BD), aggregate stability (AS), saturated hydraulic conductivity (Ks), soil water retention, texture, thermal properties, and pH were determined using soil samples collected from different depths of a twelve-year-old oil palm and rubber cultivated fields located in low country wet zone of Sri Lanka. In each field, volumetric water content (VWC) of soil was continuously measured at four soil depths (0-25, 25-50, 50-75, and 75-100 cm) over a seven-month period. While the study revealed a 40% lower SOC in 0-25 cm soil layer of the oil palm field compared to the rubber field, no significant changes were observed in BD, porosity, pore size distribution, AS, and Ks for the two fields. However, the volumetric heat capacity of rubber grown soil was significantly higher than that of the oil palm grown soil. Oil palm utilized the most water from 25-75 cm soil layer; whereas, rubber extracted more water from deeper soil layers (75-100 cm). Soil water depletion in oil palm field was faster during dry periods than in rubber fields highlighting the need to examine the soil water extraction patterns of oil palm during extended dry spells in future studies. Overall, the conversion of rubber into oil palm plantations showed no significant impact on most of the soil properties and soil hydrology after twelve years of conversion. [ABSTRACT FROM AUTHOR]

Abstract Amidst intensifying global agricultural water demand, optimizing management practices and understanding the role of soil amendments, particularly biochar (BC), in modulating soil water dynamics are critical. Here, we review the potential impacts of BC on soil water dynamics, elucidate mechanistic underpinnings, and identify critical research gaps and prospective avenues. In general, BC modifies soil structure, hydraulic properties, surface albedo, and heat fluxes, which influence soil water storage, energy balance, and irrigation paradigms. Depending on soil texture and BC properties, BC demonstrates a greater reduction in bulk density and saturated hydraulic conductivity in coarse-textured soils compared to fine-textured soils. BC application generally increases water holding capacity (WHC) while exhibiting no consistent impact on soil water infiltration. Increased WHC of soils results from increased porosity, surface area, and soil aggregation. Increased porosity arises from a confluence of factors, encompassing new pores formation, reorganization of pores, increased soil aggregation, dilution effects of BC, reduced soil compaction, and biotic interactions, including increased population of burrowing invertebrates. BC tends to increase plant-available water in coarser soils, attributed to its hydrophilic nature, augmented specific surface area, and enhanced overall porosity. However, BC may induce soil water repellency, contingent upon variables such as feedstock composition, pyrolysis temperature, and specific soil attributes. While BC exhibits transformative potential in enhancing soil hydraulic properties, scalability concerns and economic viability pose challenges to its widespread agricultural application. Overall, BC offers promising avenues for sustainable water management. However, it is imperative to explore large-scale applications and conduct long-term field studies across different management, climate, and soil types to fully understand how different types of BC impact soil water dynamics. Graphical Abstract

Amidst intensifying global agricultural water demand, optimizing management practices and understanding the role of soil amendments, particularly biochar (BC), in modulating soil water dynamics are critical. Here, we review the potential impacts of BC on soil water dynamics, elucidate mechanistic underpinnings, and identify critical research gaps and prospective avenues. In general, BC modifies soil structure, hydraulic properties, surface albedo, and heat fluxes, which influence soil water storage, energy balance, and irrigation paradigms. Depending on soil texture and BC properties, BC demonstrates a greater reduction in bulk density and saturated hydraulic conductivity in coarse-textured soils compared to fine-textured soils. BC application generally increases water holding capacity (WHC) while exhibiting no consistent impact on soil water infiltration. Increased WHC of soils results from increased porosity, surface area, and soil aggregation. Increased porosity arises from a confluence of factors, encompassing new pores formation, reorganization of pores, increased soil aggregation, dilution effects of BC, reduced soil compaction, and biotic interactions, including increased population of burrowing invertebrates. BC tends to increase plant-available water in coarser soils, attributed to its hydrophilic nature, augmented specific surface area, and enhanced overall porosity. However, BC may induce soil water repellency, contingent upon variables such as feedstock composition, pyrolysis temperature, and specific soil attributes. While BC exhibits transformative potential in enhancing soil hydraulic properties, scalability concerns and economic viability pose challenges to its widespread agricultural application. Overall, BC offers promising avenues for sustainable water management. However, it is imperative to explore large-scale applications and conduct long-term field studies across different management, climate, and soil types to fully understand how different types of BC impact soil water dynamics. Highlights: Biochar generally improves soil water retention in coarse-textured soils. In coarse-textured soils, biochar increases porosity and PAW but decreases bulk density and Ksat. The effects of biochar on infiltration rates vary depending on soil types, as well as biochar particle size, production temperature, and depth of placement. Further studies on the mechanisms governing water retention in biochar-amended soils are warranted. Long-term studies encompassing various soil and biochar types are necessary. [ABSTRACT FROM AUTHOR]

The rock fragment (RF) has been widely observed in the soil solum or on the soil surface. It regulates soil hydrological processes (SHPs) and thus has great impacts on soil and water conservation. However, responses of SHPs to RF characteristics (position, content, coverage area, mulching thickness, and size) remain unclear. Based on the dataset extracted from 168 published studies, effects of RF characteristics on SHPs (soil loss rate, evaporation rate, surface runoff rate, infiltration rate, soil water content, and soil water storage) and saturated hydraulic conductivity (Ks) were discussed in this study. Results showed that RFs completely inserted into the soil solum (CO_INS) improved the Ks by 6.9%, runoff rate by 12.8%, and soil loss rate by 22.3%, while it reduced the evaporation rate by 30.7%, infiltration rate by 15.4%, and soil water content by 9.9%. With the RF content (kg kg−1) increasing, its effects on these SHPs were strengthened. The RFs resting on the surface and partially covering soil surface (PA_COV) improved the infiltration rate but reduced the evaporation rate by 36.9%, surface runoff rate by 25.4%, and soil loss rate by 59.3%. This in turn enhanced soil water content and storage. However, as the RF coverage (% in area) increasing, the cross-sectional area of water flow decreased, and thus the infiltration rate reduced. The RFs completely mulch on the soil surface (CO_MUL) reduced the evaporation rate by 59.5% and infiltration rate by 76.5% but improved the soil water content and storage. Except the infiltration rate, the effects of CO_MUL on SHPs were strengthened as mulch thickness (cm) increased. The RFs partially embedded into soil surface (PA_EMB) promoted surface runoff rate by 15.3%, soil loss rate by 34.7%, and soil water content by 24.3%, but reduce the infiltration rate. However, the surface runoff rate was reduced at high embedded coverage due to increased tortuosity of water flow. In addition, the RF size exerted weaker effects on SHPs than RF positions, content, coverage, and mulch thickness. Our findings enhanced the understanding of SHP responses to RFs characteristics, which would be important for relate soil and water modeling and management. [ABSTRACT FROM AUTHOR]

Because tension infiltrometers apply water through a disk of finite size, the infiltrated water moves laterally as well as downward. Only the vertical component of this flow is indicative of the hydraulic conductivity K, so the algorithm for computing K must include a way of isolating that component from the total flow. Some commonly used formulas correct for the multidimensional effects by subtracting an estimate of the laterally spreading flow. For disks smaller than about 200 mm in diameter, however, lateral spreading constitutes so much of the total flow that these subtractive formulas lose considerable accuracy, and sometimes overcorrect so severely as to produce a negative number for K. Other methods rely on empiricisms that are not completely consistent with unsaturated‐flow theory and that require prior knowledge of certain soil properties. We developed a new formula that uses a multiplicative factor instead of a subtracted term to achieve the needed correction. For testing we conducted numerical experiments with synthetic data produced by solving the Richardson‐Richards equation using the code VS2DRTI, for diverse media and a range of disk sizes, including the widely used 45‐mm diameter. We compared K values calculated from our formula to the actual K used to generate the simulated data, as well as to results from other published formulas. This comparison shows that our method provides an algorithm based in unsaturated‐flow theory that produces more reliable values for small disks without requiring prior knowledge of soil properties. Plain Language Summary: Tension infiltrometers are much‐used devices for field measurement of the hydraulic conductivity of soil. Hydraulic conductivity is a measure of how easily water flows in the soil. If it is high, water at the soil surface can cause more infiltration and less runoff, and can move faster within the soil. Tension infiltrometers apply water over a circular area of the soil surface and measure the flow rate of the water being drawn into the soil. For small infiltrometers, a large fraction of the water spreads laterally within the soil, rather than straight down. Consequently, the amount of water flow measured by the infiltrometer is much greater than just the downward‐flowing portion needed to indicate hydraulic conductivity. This laterally flowing water must be corrected for in the formulas that calculate hydraulic conductivity from the measured data. If the diameter is less than about 200 mm, as it is for the great majority of infiltrometers, the needed correction is so large that large errors result from the approximate corrections applied by commonly used formulas. Our new method uses an estimate of the distance the water spreads laterally to give more accurate results. Key Points: Measurements from small diameter tension infiltrometers require a large correction to account for the lateral spreading of infiltrated waterThe use of a multiplicative, rather than subtractive, correction method provides greater accuracy when the correction is large, as needed for small disksOur proposed method provides a direct estimate of how much flow is going into lateral versus vertical components, thereby yielding additional information for interpretation as well as more accurate hydraulic conductivity results [ABSTRACT FROM AUTHOR]

Syntropic agroforestry systems (SYS) are a type of agroforestry in which very large amounts of organic matter (50–100 t ha−1 year−1) are added to the soil annually from pruning. However, information on the physical, chemical and biological effects of this management on soil is lacking. We characterized a SYS in terms of topsoil permeability (Mini‐Disk infiltrometer), soil organic matter (ignition method) and penetration resistance (Stolf penetrometer); we compared the results with those for a no‐till soy‐maize rotation and those within a native vegetation area (Brazilian Tropical Savanna), all on the same oxisol. The SYS had an infiltration capacity similar to that in the native vegetation area but which was higher than in the no‐till arable rotation. We relate this difference to both a lower penetration resistance and a high organic matter content in the SYS, possibly associated with higher litter input and with a greater above and belowground biomass. Our results indicate that SYS can be an efficient system for maintaining water infiltration at levels similar to those observed within natural ecosystems. [ABSTRACT FROM AUTHOR]

Forest planting is increasingly being incorporated into land management policies to mitigate diffuse pollution and localised flooding because forest soils are associated with enhanced hydraulic properties and lower surface runoff compared to soils under other vegetation types. Despite this, our understanding of the effects of different tree species and forest land use on soil hydraulic properties is limited. In this study we tested for the effects of two tree species, sycamore ( Acer pseudoplatanus ) and Scots pine ( Pinus sylvestris ), subject to contrasting land use systems, namely ungrazed forest and livestock grazed forest, on soil surface saturated hydraulic conductivity ( K fs ) at a long term (23 year) experimental site in Scotland. Additionally these forest land use systems were compared to grazed pasture. K fs was found to be significantly higher under ungrazed Scots pine forest (1239 mm hr − 1 ) than under ungrazed sycamore forest (379 mm hr − 1 ) and under both of these forest types than under pasture (32 mm hr − 1 ). However, this measure did not differ significantly between the sycamore and Scots pine grazed forest and pasture. It was inferred, from comparison of measured K fs values with estimated maximum rainfall intensities for various return periods at the site, that surface runoff, as infiltration excess overland flow, would be generated in pasture and grazed forest by storms with a return period of at least 1 in 2 years, but that surface runoff is extremely rare in the ungrazed forests, regardless of tree species. We concluded that, although tree species with differing characteristics can create large differences in soil hydraulic properties, the influence of land use can mask the influence of trees. The choice of tree species may therefore be less important than forest land use for mitigating the effects of surface runoff. [ABSTRACT FROM AUTHOR]

Soil pedotransfer functions (PTFs) are alternatives to expensive field and laboratory methods for acquiring soil hydraulic properties. Traditional PTFs generally require soil physiochemical properties (such as particle size distribution, bulk density, soil organic matter, etc.) as inputs. Soil spectral information is, more recently, being considered as an additional input property for improving the performance of PTFs. To date, however, there are only a few studies focused on this issue. Using 171 in-situ saturated soil hydraulic conductivity (Ks) observations in southwestern China and an Artificial Neural Network model (ANN), we developed three different PTFs, with different inputs, to estimate the saturated hydraulic conductivity. The inputs include the basic soil properties (denoted as BSP, bulk density, % clay, % silt and % sand) and soil spectral data (SPRD, dimension reduced by using the principal component analysis (PCA) method). We evaluated the performance of the new PTFs using the determination coefficient (R 2 ), root mean square error (RMSE) and Akaike's information criterion (AIC). The results showed that including the SPRD as an additional input improved the performance of the PTF for estimating Ks. Compared to the PTF that solely used BSP as inputs, the R 2 of the PTF, which used both the BSP and SPRD as inputs, increased by 0.33 (from 0.09 to 0.42) and the RMSE and AIC decreased by 0.26 (from 1.38 to 1.12) and 18.16 (from 273.96 to 255.8), respectively. These results indicate the potential of SPRD to improve the performance of PTF in estimating hydraulic conductivity. [ABSTRACT FROM AUTHOR]

Pristine peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosity, von Post degree of decomposition) in soil profiles of two peatland forests, a cultivated peatland, a peat extraction area and two pristine mires originally within the same peatland area. Soil hydraulic conductivity of the drained sites (median hydraulic conductivities: 3.3 × 10−5 m/s, 2.9 × 10−8 m/s and 8.5 × 10−8 m/s for the forests, the cultivated site and the peat extraction area, respectively) was predicted better by land use option than by soil physical parameters. Detailed physical measurements were accompanied by monitoring of the water levels between drains. The model ' DRAINMOD' was used to assess the hydrology and the rapid fluctuations seen in groundwater depths. Hydraulic conductivity values needed to match the simulation of observed depth to groundwater data were an order of magnitude greater than those determined in field measurements, suggesting that macropore flow was an important pathway at the study sites. The rapid response of depth to groundwater during rainfall events indicated a small effective porosity and this was supported by the small measured values of drainable porosity. This study highlighted the potential role of land use and macropore flow in controlling water table fluctuation and related processes in peat soils. [ABSTRACT FROM AUTHOR]

Nature-based solutions to engineering challenges are essential to limit climate change impacts on the urban environment. Quantitative understanding of multiple "engineering functions" provided by soil-plant interactions of different species is needed for species selection and re-establishing natural processes affected by urbanisation. Contrasting herbaceous species (legumes, grasses, and forbs) were selected and grown as monoculture or species mix in soil columns for a five-month growing season. Saturated hydraulic conductivity was initially tested for each column, and then the columns were monitored for three-weeks of evapotranspiration. Water loss, matric suction, and penetrometer resistance were measured. Finally, soil was tested for aggregate stability and water retention. Saturated hydraulic conductivity of vegetated soil was generally larger than that of fallow soil (6.9e−6 ± 1.4e−6 m/s in fallow soil). Saturated hydraulic conductivity was significantly different between species (e.g., from 9.9e−6 ± 1.3e−6 m/s in Festuca ovina to 3.9e−5 ± 1.2e−6 m/s in Lotus corniculatus) and was negatively correlated with specific root length. The water stored in the soil was efficiently removed by plant transpiration (> 60% of evapotranspiration). Large changes in soil structure were observed in vegetated soil, with significant increases in soil strength, aggregate stability, and alteration of water retention properties. Multiple soil-plant interactions influence species selection for optimising nature-based solutions (e.g., bioretention barriers). Substantial scope exists to choose species mixes to manipulate soil hydro-mechanical properties. Enhanced biodiversity did not compromise the engineering services of nature-based solutions (e.g., water removal), and may have multiple benefits. • Contrasting herbaceous species were investigated for multiple soil-plant interactions. • Saturated hydraulic conductivity of soil significantly differed between species. • Plants significantly affected aggregate stability and water retention properties. • We can enhance biodiversity without compromising the engineering services. • There is a substantial scope to choose species to manipulate soil properties. [ABSTRACT FROM AUTHOR]

• Soil hydrological properties are improved after 20 years of vegetation restoration. • Shrubland and forest have higher K S than grassland and cropland in the Loess Plateau. • Soil porosity and bulk density explain 93.8% of soil hydrological properties variation. • Locally-developed PTF of K S using bulk density, Clay and Silt shows good performance. Soil hydrological properties play a key role in soil hydrological processes. However, the effect of long-term vegetation restoration on soil hydrological properties and the corresponding influencing mechanisms remains poorly understood. Here, three soil hydrological properties including saturated water-holding capacity (SWHC), field capacity (FC) and saturated hydraulic conductivity (Ks), as well as several basic soil properties in the Zhifanggou watershed of the Loess plateau were investigated. The variations in SWHC, FC and Ks under different vegetation restoration types and their dominant influencing factors were analyzed. Moreover, we collected available Ks data from peer-reviewed publications to determine the land use with the largest Ks across the entire Loess Plateau. The results showed that SWHC FC and Ks were increased after 20 years of vegetation restoration. The higher Ks was found in shrubland and forest in the whole Loess Plateau. Compared with cropland, Ks in shrubland was increased by 87.10% at 0–20 cm, 48.89% at 20–40 cm, and 18.37% at 40–100 cm, respectively, indicating that the impact of revegetation on Ks were most obvious in the upper soil layer. Bulk density (BD), total porosity (TP), capillary porosity (CP), noncapillary porosity (NCP) and soil organic matter (SOM) had a significant effect on SWHC, FC and Ks for different land-use types (P < 0.01). Soil porosity (i.e., TP, CP and NCP) and BD, soil chemical properties (i.e., SOM and pH), and soil particle composition explained 93.8%, 59.2%, and 13.4% of the total variance in soil hydrological properties (i.e., SWHC, FC and Ks), respectively. This indicates that soil porosity and BD are the dominant factors affecting soil hydrological properties. Moreover, soil particle composition played an important role in regulating Ks, with the contribution of 38.6%. The established pedotransfer function (PTF) of Ks using BD, clay and silt content had a better performance than two existing PTFs. This research provides a more systematic and comprehensive understanding of the soil hydrological effect of vegetation restoration in the Loess Plateau. [ABSTRACT FROM AUTHOR]

Many peatlands have been subjected to wildfire or prescribed burning, but it is not known how these fires influence near-surface hydrological processes. Macropores are important flowpaths in the upper layers of blanket peat and were investigated through the use of tension disc infiltrometers, which also provide data on saturated hydraulic conductivity. Measurements were performed on unburnt peat (U), where prescribed burning had taken place 2 years (B2), 4 years (B4) and >15 (B15+) years prior to sampling, and where a wildfire (W) had taken place 4 months prior to sampling. Where there had been recent burning (B2, B4 and W), saturated hydraulic conductivity was approximately three times lower than where there was no burning (U) or where burning was last conducted >15 years ago (B15+). Similarly, the contribution of macropore flow to overall infiltration was significantly lower (between 12% and 25% less) in the recently burnt treatments compared to B15+ and U. There were no significant differences in saturated hydraulic conductivity or macropore flow between peat that had been subject to recent wildfire (W) and those that had undergone recent prescribed burning (B2 and B4). The results suggest that fire influences the near-surface hydrological functioning of peatlands but that recovery in terms of saturated hydraulic conductivity and macropore flow may be possible within two decades if there are no further fires. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Variations in slope, exposure, relief and substrate over a short distance and their influences on plant function are poorly understood. We investigated the influences of soil hydrological characteristics on internal stem structure and hydraulic properties of downy oak (Quercus pubescens Willd.) growing along a hill slope. Increment wood cores were extracted from the base and at breast height (BH) of tree stems. Relative wood water content (Wc) and wood density (Dw) were measured in the sapwood. Wood compression strength (δ) in the longitudinal direction was measured with a fractometer. Thin sections were cut from the transversal face of each core and vessel lumen area (VA) was measured and xylem theoretical hydraulic conductivity (Lth) estimated over the sapwood. Topsoil volumetric water content (θv) was determined around trees and the hydrological behavior of the slope was studied through field surveys. Data were used as input to a hydrological model to simulate topsoil water distribution along the slope. Results showed that θv tends to decrease with increasing altitude. Groundwater levels were lower upslope than downslope, and results from the hydrological model confirmed these trends. Mean Wc at the base of each tree decreased significantly with increasing altitude, whereas at BH, no differences were found along the slope. There was a significant positive relationship between Wc measured at the tree base and θv along the hill slope, but not for Wc measured at BH. Values of Dw and δ measured at both stem positions increased significantly with increasing altitude and decreasing θv. Significant negative relationships were found between δ and θv measured at the stem base and at BH. At both stem positions, δ was closely related to Dw and Lth. Vessel lumen areas at BH and the stem base were significantly regressed with altitude, θv, Dw and δ. Xylem theoretical hydraulic conductivity at both stem positions was negatively related to altitude and soil θv, but only Lth measured at the stem base was negatively regressed with Dw. The results are discussed in the context of how tree position along a hill slope influences water uptake and internal xylem structure. [ABSTRACT FROM AUTHOR]

Soil hydrological properties like infiltration capacity and hydraulic conductivity have important consequences for hydrological properties of soils in river catchments and for flood risk prevention. They are dynamic properties due to varying land use management practices. The objective of this study was to characterize the variation of infiltration capacity, hydraulic conductivity and soil organoprofile development on forest sites with comparable geological substrate, soil type and climatic conditions, but different stand ages and tree species in terms of the effects of forest transformation upon soil hydrological properties. The Kahlenberg forest area (50 km northeast of Berlin in the German northeastern lowlands) under investigation contains stands of Scots pine ( Pinus sylvestris) and European beech ( Fagus sylvatica) of different age structures forming a transformation chronosequence from pure Scots pine stands towards pure European beech stands. The water infiltration capacity and hydraulic conductivity (K) of the investigated sandy-textured soils are low and very few macropores exist. Additionally these pores are marked by poor connectivity and therefore do not have any significant effect on water infiltration rate. Moreover, water infiltration in these soils is impeded by their hydrophobic properties. Along the experimental chronosequence of forest transformation, the thickness of the forest floor layer decreases due to enhanced decomposition and humification intensities. By contrast, the thickness of the humous topsoil increases. Presumably, changes in soil organic matter storage and quality caused by the management practice of forest transformation affect the persistence and degree of water repellency in the soil, which in turn influences the hydraulic properties of the experimental soils. The results indicate clearly that soils play a crucial role for water retention and therefore, in overland flow prevention. There is a need to have more awareness on the intimate link between the land use and soil properties and their possible effects on flooding. [ABSTRACT FROM AUTHOR]

Direct measurement of unsaturated hydraulic parameters is costly and time-consuming. Pedotransfer functions (PTFs) are typically developed to estimate soil hydraulic properties from readily available soil attributes. For the first time, in this study, we developed PTFs to estimate the soil hydraulic conductivity (log(K)) directly from measured data. We adopted the pseudo continuous neural network PTF (PCNN-PTF) approach and assessed its accuracy and reliability using two independent data sets with hydraulic conductivity measured via the evaporation method. The primary data set contained 150 international soils (6963 measured data pairs), and the second dataset consisted of 79 repacked Turkish soil samples (1340 measured data pairs). Four models with different combinations of the input attributes, including soil texture (sand, silt, clay), bulk density (BD), and organic matter content (SOM), were developed. The best performing international (root mean square error, RMSE = 0.520) and local (RMSE = 0.317) PTFs only had soil texture information as inputs when developed and tested using the same data set to estimate log(K). However, adding BD and SOM as input parameters increased the reliability of the international PCNN-PTFs when the Turkish data set was used as the test data set. We observed an overall improvement in the performance of PTFs with the increasing number of data points per soil textural class. The PCNN-PTFs consistently performed high across tension ranges when developed and tested using the international data set. Incorporating the Turkish data set into PTF development substantially improved the accuracy of the PTFs (on average close to 60% reduction in RMSE). Consequently, we recommend integrating local HYPROPTM (Hydraulic Property Analyzer, Meter Group Inc., USA) data sets into the international data set used in this study and retraining the PCNN-PTFs to enhance their performance for that specific region. [ABSTRACT FROM AUTHOR]

This study discusses the influence of soil compaction on runoff generation with a special focus on forested Andosol sites. Because of their typical soil physical characteristics (low bulk density, high pore volumes) and the existent land use, these areas are expected to show low to no measurable overland flow during heavy rainfall events. However, due to heavy machinery traffic in the course of forestry actions and pumice excavations, skid trails have been established. Here, a distinct shift of soil dry bulk density (DBD) was observable, using a detailed soil mapping and data interpolation in order to generate in-depth DBD-cross profiles. Additionally, infiltration measurements and rainfall simulations (I = 45 mm·h−1, t = 30 min) were conducted to evaluate effects of observed soil compaction on infiltration rates and overland flow formation. Results show that soil compaction was increased by 21% on average in skid trail wheel ruts. As a consequence, observed runoff was 8.5-times higher on skid trails, while saturated hydraulic conductivity was diminished by 36%. These findings show, that soil compaction leads to a higher possibility of runoff formation during heavy rainfall events, especially at sites which showed initial conditions with presumably low tendencies of runoff formation. [ABSTRACT FROM AUTHOR]