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Among its many functions, soil represents the active natural medium for plant growth. Different soils have various structural characteristics, that correspond to their qualitative parameters in terms of physical, chemical, and biological fertility. Because of their extremely slow formation processes, soils are also a non-renewable resource, easily subject to degradative processes. Among their mineral constituents many agrarian soils present, in addition to the fine earth, variable percentages of coarse fractions in their arable layer, which interfere with the crop growth, requiring more energy to manage cultivation operations, and damaging the machinery up to making its use impractical. In these conditions, it becomes necessary to proceed with the soil destoning, particularly for the management of Precision Farming techniques. Depending on the percentages, sizes and types of coarse fractions, the soil destoning systems concern: (i) the collection and removal of stones from the field, (ii) the on-site stones crushing, and (iii) the stone burial. In this article, we report the first evaluation of a deep burial destoning system carried out in the CREA Experimental Center of Treviglio (Italy). With the described reclamation system, a significant long-term improvement of soil quality in a 600 mm thick arable layer was achieved; avoiding the shortcomings of the destoning systems as commonly applied in agricultural lands.

Geodiversity integrates physical parameters such as geological, geomorphological, and pedological components. It represents the abiotic diversity of the earth surface layer. It incorporates geological (bedrocks and mineral sediments), geomorphological (geography, land surface formations, physical processes), pedological (soils), and hydrological characteristics. Biological soil crusts (biocrusts) play an essential role in regulating the biogeochemical cycles of carbon and nitrogen. Their ability is dependent on habitat conditions, composition, and cover percentage of the ground surface, all of which are affected by geodiversity. This study’s objective was to assess the effects of geodiversity on the biogeochemical functions of biocrusts by regulating the soil water dynamics and the subsequent impact on readily available nitrogen and carbon. Hillslope geodiversity is determined by the geodiversity found in the stone cover on the ground surface and in the stone content throughout the soil profile, as well as by the soil profile thickness of the underlying bedrock. We hypothesized that in dry environments, the physical conditions in high-geodiversity hillslopes, compared to low-geodiversity hillslopes, positively affect the soil water budget, which would affect the biocrusts and their readily available nitrogen and carbon. The results showed higher soil moisture content in the heterogeneous hillslopes. The ammonium and labile organic carbon in the biocrusts were more substantial in the heterogeneous than in the homogeneous hillslopes, while soil protein, nitrite, and soil organic matter were similar. We suggest that the comparatively high soil moisture content in the heterogeneous hillslopes stimulates biocrust community activities and increases the readily available nitrogen and carbon, thus improving the survival of shrubs in these ecosystems under long-term drought conditions. [ABSTRACT FROM AUTHOR]

Among its many functions, soil represents the active natural medium for plant growth. Different soils have various structural characteristics, that correspond to their qualitative parameters in terms of physical, chemical, and biological fertility. Because of their extremely slow formation processes, soils are also a non-renewable resource, easily subject to degradative processes. Among their mineral constituents many agrarian soils present, in addition to the fine earth, variable percentages of coarse fractions in their arable layer, which interfere with the crop growth, requiring more energy to manage cultivation operations, and damaging the machinery up to making its use impractical. In these conditions, it becomes necessary to proceed with the soil destoning, particularly for the management of Precision Farming techniques. Depending on the percentages, sizes and types of coarse fractions, the soil destoning systems concern: (i) the collection and removal of stones from the field, (ii) the on-site stones crushing, and (iii) the stone burial. In this article, we report the first evaluation of a deep burial destoning system carried out in the CREA Experimental Center of Treviglio (Italy). With the described reclamation system, a significant long-term improvement of soil quality in a 600 mm thick arable layer was achieved; avoiding the shortcomings of the destoning systems as commonly applied in agricultural lands. [ABSTRACT FROM AUTHOR]

This database consists of a digital photograph set of soil profiles from the physiographic provinces of the Trans-Mexican Neovolcanic Axis and Sierra Madre del Sur of central Mexico. Although the official and government databases of soil profiles from Mexico do not contain the percentage of coarse fragments (stoniness), they contain soil profile photographs from which the percentage of coarse fragments can be extracted. The dataset has two data source types: (a) Soil profile photographs taken in the field and (b) soil profile photographs from the official database of the government of Mexico. The images were analyzed using the Gallegos-Bautista (GB) method. In the GB method, the horizon delineation of the soil profiles includes preprocessing the profile image with k-means segmentation; conversion of the preprocessed image to CIE L*a*b* (lightness, red/green value, blue/yellow value) and HSV (hue, saturation, value) color systems; k-means segmentation of HSV and CIE L*a*b* images, delineation of horizons, and clarity and topography determinations of the outlined horizons. The soil groups studied correspond to the Andosol, Cambisol, Luvisol, Alisol, Kastanozem, Phaeozem, Umbrisol, and Solonchak groups, some of which had contrasting color horizons, allowing us to identify how to follow the analysis of the digital images according to the horizons of the soil profiles.

Geodiversity integrates physical parameters such as geological, geomorphological, and pedological components. It represents the abiotic diversity of the earth surface layer. It incorporates geological (bedrocks and mineral sediments), geomorphological (geography, land surface formations, physical processes), pedological (soils), and hydrological characteristics. Biological soil crusts (biocrusts) play an essential role in regulating the biogeochemical cycles of carbon and nitrogen. Their ability is dependent on habitat conditions, composition, and cover percentage of the ground surface, all of which are affected by geodiversity. This study’s objective was to assess the effects of geodiversity on the biogeochemical functions of biocrusts by regulating the soil water dynamics and the subsequent impact on readily available nitrogen and carbon. Hillslope geodiversity is determined by the geodiversity found in the stone cover on the ground surface and in the stone content throughout the soil profile, as well as by the soil profile thickness of the underlying bedrock. We hypothesized that in dry environments, the physical conditions in high-geodiversity hillslopes, compared to low-geodiversity hillslopes, positively affect the soil water budget, which would affect the biocrusts and their readily available nitrogen and carbon. The results showed higher soil moisture content in the heterogeneous hillslopes. The ammonium and labile organic carbon in the biocrusts were more substantial in the heterogeneous than in the homogeneous hillslopes, while soil protein, nitrite, and soil organic matter were similar. We suggest that the comparatively high soil moisture content in the heterogeneous hillslopes stimulates biocrust community activities and increases the readily available nitrogen and carbon, thus improving the survival of shrubs in these ecosystems under long-term drought conditions.

Drought‐related tree mortality had become a widespread phenomenon in forests around the globe. This process leading to these events and its complexity is not fully understood. Trees in the dry timberline are exposed to ongoing drought, and the available water for transpiration in the soil can determine their survival chances.Recent drought years led to 5%–10% mortality in the semi‐arid pine forest of Yatir (Israel). The distribution of dead trees was, however, highly heterogeneous with parts of the forest showing >80% dead trees (D plots) and others with mostly live trees (L plots). At the tree level, visible stress was associated with low pre‐dawn leaf water potential at the dry season (−2.8 MPa vs. −2.3 MPa in non‐stressed trees), shorter needles (5.5 vs. 7.7 mm) and lower chlorophyll content (0.6 vs. 1 mg/g dw). Trends in tree‐ring widths reflected differences in stress intensity (30% narrower rings in stressed compared with unstressed trees), which could be identified 15–20 years prior to mortality.At the plot scale, no differences in topography, soil type, tree age or stand density could explain the mortality difference between the D and L plots. It could only be explained by the higher surface rock cover and in stoniness across the soil profile in the L plots. Simple bucket model simulations using the site's long‐term hydrological data supported the idea that these differences could result in higher soil water concentration (m3/m3) in the L plots and extend the time above wilting point by several months across the long dry season.Accounting for subsurface heterogeneity may therefore critical to assessing stand‐level response to drought and projecting tree survival, and can be used in management strategies in regions undergoing drying climate trends. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Stony soils are composed of fractions (rock fragments and fine soil) with different hydrophysical characteristics. Although they are abundant in many catchments, their properties are still not well understood. This article presents basic characteristics (texture, stoniness, saturated hydraulic conductivity, and soil water retention) of stony soils from a mountain catchment located in the highest part of the Carpathian Mountains and summarizes results of water flow modeling through a hypothetical stony soil profile. Numerical simulations indicate the highest vertical outflow from the bottom of the profile in soils without rock fragments under ponding infiltration condition. Simulation of a more realistic case in a mountain catchment, i.e. infiltration of intensive rainfall, shows that when rainfall intensity is lower than the saturated hydraulic conductivity of the stony soil, the highest outflow is predicted in a soil with the highest stoniness and high initial water content of soil matrix. Relatively low available retention capacity in a stony soil profile and consequently higher unsaturated hydraulic conductivity leads to faster movement of the infiltration front during rainfall.

Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. The effect of topographic and vegetation variables, on stoniness, bulk density and soil carbon has been explored in a 2.7 km 2 watershed of Sierra Morena in south Spain. Soil core samples were collected from 67 locations at 6 depths up to 0,3 m. Stoniness and bulk density were measured with standard methods, total organic carbon through elemental analysis. These soil properties were then used to calculate carbon stock and related to solar insolation, elevation, slope, curvature, TWI, TPI, SPI and NDVI. Stone content depends on slope, indicating the importance of water erosion on long-term soil development. Spatial distribution of bulk density was found to be highly random. By means of conventional statistical methods, with the help of a random forest method, solar radiation and NDVI proved to be the key variable controlling soil carbon distribution. Total soil organic carbon stocks were 4.38 kg m − 2 on average, with stocks about double as high on north versus south-facing slopes. These results confirm the importance of the coupled soil moisture and vegetation dynamics on the carbon balance in semi-arid ecosystems. However, validation of the random forest model showed that the different covariates only explained 18% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain the full variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Future improvement of mechanistic soil formation models could help estimating these soil properties better. [ABSTRACT FROM AUTHOR]

An analysis of 428 geobotanical descriptions of steppe vegetation in the Bashkir Trans-Urals has revealed plant species that indicate a relationship between the communities and soil moisture and stoniness. We use the ANOVA-based technique of defining indicator species groups for uneven complexes. The role of indicator species groups in diagnostic combinations of Trans-Ural higher rank steppe syntaxa that represent the steppe vegetation of the region has been determined. [ABSTRACT FROM AUTHOR]

• Damage to seedlings was not correlated with numbers of trapped pine weevils. • This lack of correlation may be due to extensive feeding on other food sources. • Availability of alternative food may vary considerably between regeneration sites. • Trap catch data are thus unlikely to be useful for predicting damage risk. Damage to planted conifer seedlings caused by the pine weevil Hylobius abietis (L.) is a severe and persistent threat to successful forest regeneration in Europe. Various countermeasures are available, which vary in effectiveness, costs and environmental impact, but none are ideal for all situations. Therefore, there is strong interest in robust assessments of damage risks, as they would enable more cost-effective and environmentally friendly forest pest management. It has been suggested that numbers of adult pine weevils caught in host-odour baited traps placed in regeneration sites may be valuable in such risk assessments. However, published studies provide at most weak support for the hypothesis that trap catch data provide adequate predictions of damage. Therefore, we conducted a two-year field study, designed to determine the relationship between weevil trap catch and subsequent damage at 10 regeneration sites in central Sweden. Site factors that might influence pine weevil feeding on seedlings were recorded and used as explanatory variables in the analysis. Stoniness was the only site factor identified as having a significant effect; damage mainly increased with increases in stoniness. No significant correlation was detected between damage to planted conifer seedlings and numbers of pine weevils trapped in the same locations. We suggest that this lack of correlation between weevil numbers and damage is due to planted seedlings only constituting a minor part of the weeviĺs food intake and considerable between-site variation in availability of food sources other than seedlings. Therefore, assessment of pine weevil numbers appears unlikely to be useful for predicting damage risk at specific regeneration sites. [ABSTRACT FROM AUTHOR]

Long-term estimates of the water balance of forests are essential for forest ecosystem analysis. Such estimates can be achieved by using numerical modelling approaches for water balance calculations. These modelling approaches require data, e.g., for the description of the hydraulic properties of forest soils using soil water retention or hydraulic conductivity functions. However, these functions are usually valid only for fine-earth conditions. However, many forest soils, especially those located in mountainous regions, contain larger fractions of gravel and rock fragments in the soil profiles. In our study, the impact of stoniness correction of soil hydraulic functions on the performance of a numerical water balance modelling approach was evaluated by using continuously measured time series of daily throughfall, soil water contents and pressure heads provided from three different ICP Forests Level II plots with high stoniness in the soil profiles. These measured data were compared with the corresponding model outputs. The application of stoniness correction of the soil hydraulic functions improved the model performance in terms of the Nash-Sutcliffe Index NS and the coefficient of determination R2. This indicated the need for such a correction. [ABSTRACT FROM AUTHOR]

Three methods to estimate the presence of ground surface stones from publicly available Airborne Laser Scanning (ALS) point clouds are presented. The first method approximates the local curvature by local linear multi-scale fitting, and the second method uses Discrete-Differential Gaussian curvature based on the ground surface triangulation. The third baseline method applies Laplace filtering to Digital Elevation Model (DEM) in a 2 m regular grid data. All methods produce an approximate Gaussian curvature distribution which is then vectorized and classified by logistic regression. Two training data sets consisted of 88 and 674 polygons of mass-flow deposits, respectively. The locality of the polygon samples is a sparse canopy boreal forest, where the density of ALS ground returns is sufficiently high to reveal information about terrain micro-topography. The surface stoniness of each polygon sample was categorized for supervised learning by expert observation on the site. The leave-pair-out (L2O) cross-validation of the local linear fit method results in the area under curve AUC = 0.74 and AUC = 0.85 on two data sets, respectively. This performance can be expected to suit real world applications such as detecting coarse-grained sediments for infrastructure construction. A wall-to-wall predictor based on the study was demonstrated. [ABSTRACT FROM AUTHOR]

Few if any methods exist to estimate the effects of stone content (stoniness) on the unsaturated soil hydraulic properties. A relatively simple scaling method is presented to estimate the hydraulic conductivity of unsaturated stony soils having different stone contents. A key assumption of the method is that van Genuchten's water retention parameters α and n of the fine soil fraction are the same as those of the stony soil. The method further assumes a linearly decreasing relationship between the saturated hydraulic conductivity and the stone content, based on previous numerical simulations. Using the proposed method, it is possible to calculate the hydraulic conductivity of unsaturated stony soils, knowing the saturated hydraulic conductivity of the fine soil fraction, the retention curve of the fine soil fraction, and the particular stoniness of the soil. [ABSTRACT FROM AUTHOR]

Abstract: The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. One key parameter for modelling soil erosion is the soil erodibility, expressed as the K-factor in the widely used soil erosion model, the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). The K-factor, which expresses the susceptibility of a soil to erode, is related to soil properties such as organic matter content, soil texture, soil structure and permeability. With the Land Use/Cover Area frame Survey (LUCAS) soil survey in 2009 a pan-European soil dataset is available for the first time, consisting of around 20,000 points across 25 Member States of the European Union. The aim of this study is the generation of a harmonised high-resolution soil erodibility map (with a grid cell size of 500m) for the 25 EU Member States. Soil erodibility was calculated for the LUCAS survey points using the nomograph of Wischmeier and Smith (1978). A Cubist regression model was applied to correlate spatial data such as latitude, longitude, remotely sensed and terrain features in order to develop a high-resolution soil erodibility map. The mean K-factor for Europe was estimated at 0.032thahha−1 MJ−1 mm−1 with a standard deviation of 0.009thahha−1 MJ−1 mm−1. The yielded soil erodibility dataset compared well with the published local and regional soil erodibility data. However, the incorporation of the protective effect of surface stone cover, which is usually not considered for the soil erodibility calculations, resulted in an average 15% decrease of the K-factor. The exclusion of this effect in K-factor calculations is likely to result in an overestimation of soil erosion, particularly for the Mediterranean countries, where highest percentages of surface stone cover were observed. [Copyright &y& Elsevier]

Stony soils are composed of fractions (rock fragments and fine soil) with different hydrophysical characteristics. Although they are abundant in many catchments, their properties are still not well understood. This article presents basic characteristics (texture, stoniness, saturated hydraulic conductivity, and soil water retention) of stony soils from a mountain catchment located in the highest part of the Carpathian Mountains and summarizes results of water flow modeling through a hypothetical stony soil profile. Numerical simulations indicate the highest vertical outflow from the bottom of the profile in soils without rock fragments under ponding infiltration condition. Simulation of a more realistic case in a mountain catchment, i.e. infiltration of intensive rainfall, shows that when rainfall intensity is lower than the saturated hydraulic conductivity of the stony soil, the highest outflow is predicted in a soil with the highest stoniness and high initial water content of soil matrix. Relatively low available retention capacity in a stony soil profile and consequently higher unsaturated hydraulic conductivity leads to faster movement of the infiltration front during rainfall. [ABSTRACT FROM AUTHOR]

Abstract: Studies concerning the stoniness of arable soils are scarce since those soils are commonly regarded as composed mainly of fine earth. However, even the influence of lesser volumes of stones and gravel on estimates of nutrient stocks may be significant. Nutrient analyses are performed on the fine earth fraction. It is therefore necessary to determine the bulk density and the relative soil volume that is occupied by fine earth when expressing nutrient stocks per unit area and to a certain depth. In this study, relative volumes of stones and gravel were investigated in the top soils, i.e. down to 30cm depth, of five Swedish arable sites. Bulk density and gravel volume were determined by soil coring and stone volume using the rod penetration method. A function for estimation of relative stone volume from mean penetration depth was developed. The function is suitable for soils with low stoniness, i.e. less than 10%. The results showed that although the relative volumes of stones and gravel were small, at most 8%, neglecting the volume occupied by rock fragments led to an overestimation of C and N stocks by 8–9%. The moderate volumes of stones and gravel also significantly affected comparisons between sites. It was concluded that the inclusion of stone and gravel volume of arable soils may be important if nutrient stocks of different sites are compared, or the effects of land use changes are scaled up to regional or global levels. [Copyright &y& Elsevier]

Abstract: Analysing the properties and functional characteristics of heterogeneous soils containing several phases requires a correct estimation of the volume proportion of each phase. In the case of stony soils, the volume percentage of the content of rock fragments remains difficult to estimate in situ. This paper presents a method that uses field spatial electrical resistivity measurements to determine the volume proportion of rock fragments. Based on the hypothesis that the electrical resistivity signal noise increases as the proportion of rock fragments increases, a model was developed that uses the standard deviation of the apparent electrical resistivity measurements over a small area as an indicator of rock fragment contents. The model was tested on three study areas of several hectares containing soil units with varying quantities of rock fragments. The estimation of the rock fragment content was accurate, and the error estimation of about 6% was the same order of magnitude as the Bussian model (1983). The developed model strongly depends on the water content in the soil and the rock type and must be calibrated in each context. Nevertheless, estimations of the rock fragment content in stony soils can be performed efficiently in the surface horizon as well as all along the soil profile. [Copyright &y& Elsevier]

Soil and water are vital resources for agricultural land and human life. Productive utilizing of these sources is an important topic for sustainable cultivation. This study was investigated to determine areas of stoniness and erosion problems by using data obtained from different government organizations from past to present in Konya province (Turkey).The study was based on records obtained in different years (1968, 1978, 1985, 2003). The findings were evaluated with each other by considering record years. However, all problematic areas within arable lands and some improved lands in those problematic lands for Konya were shown in maps.The current problem areas of stoniness, water-wind erosion are 915.584 ha, 2.804.633 ha, respectively. In addition, improvement studies were not conducted after 1985. Consequently, solution of these problems in cultivated land may be possible when we use suitable techniques of soil cultivation by improving soil against stoniness and erosion problems and pay attention to forestation. [ABSTRACT FROM AUTHOR]

Abstract: An extensive database of short to medium-term erosion rates as measured on erosion plots in Europe under natural rainfall was compiled from the literature. Statistical analysis confirmed the dominant influence of land use and cover on soil erosion rates. Sheet and rill erosion rates are highest on bare soil; vineyards show the second highest soil losses, followed by other arable lands (spring crops, orchards and winter crops). A land with a permanent vegetation cover (shrubs, grassland and forest) is characterised by soil losses which are generally more than an order of magnitude lower than those on arable land. Disturbance of permanent vegetation by fire leads to momentarily higher erosion rates but rates are still lower than those measured on arable land. We also noticed important regional differences in erosion rates. Erosion rates are generally much lower in the Mediterranean as compared to other areas in Europe; this is mainly attributed to the high soil stoniness in the Mediterranean. Measured erosion rates on arable and bare land were related to topography (slope steepness and length) and soil texture, while this was not the case for plots with a permanent land cover. We attribute this to a fundamental difference in runoff generation and sediment transfer according to land cover types. On the basis of these results we calculated mean sheet and rill erosion rates for the European area covered by the CORINE database: estimated rill and interrill erosion rates are ca. 1.2tha−1 year−1 for the whole CORINE area and ca. 3.6tha−1 year−1 for arable land. These estimates are much lower than some earlier estimates which were based on the erroneous extrapolation of small datasets. High erosion rates occur in areas dominated by vineyards, the hilly loess areas in West and Central Europe and the agricultural areas located in the piedmont areas of the major European mountain ranges. [ABSTRACT FROM AUTHOR]

The article discusses the effects of weather condition on soil erodibility. The paper aims to consider whether climate affects the condition of soils to water erosion. The study collected soil erodibility data using measured soil loss from standard run-off plots. It illustrates the strong climate effect on soil by calculating seasonal variation of mean monthly soil erodibility. Soil erodibilities are divided into two large groups, one corresponding to soils in cool climate and another to soils located in warm climates.

Geodiversity effects on ecosystem productivity were investigated using remotely sensed data and a mathematical model, by introducing a spatially non-uniform surface-water infiltration. Two hillslope types, with different geodiversity levels, as determined by the soil depth and stoniness, were selected for this study. Low-geodiversity hillslopes ('homogenous hillslopes') were identified by their dense herbaceous vegetation cover, and lack of rock fragments cover. High-geodiversity hillslopes ('heterogeneous hillslopes') are characterized by a more sparse cover of herbaceous vegetation, and relatively high rock fragment cover (>20%). Calculating Soil Water Index (SWI) from Landsat-5 TM, Landsat-7 ETM+ (SLC-ON) and Landsat-8 satellite images for the years 1994–2017 shows that during most of these years, SWI was higher at the heterogeneous hillslopes. This was particularly prominent after 2009 when mass mortality of shrubs took place on the homogenous hillslopes but not in the heterogeneous ones. Numerical simulations show that after a prolonged drought, the vegetation in the homogenous system dried out, and the system did not recover even after the yearly rainfall amounts returned to normal. In the heterogeneous system, the vegetation patches survived the drought episode and then recovered. This demonstrates the crucial role played by hillslope geodiversity in determining the durability of vegetation under prolonged droughts in semiarid regions. • The study area includes two hillslope types that differ by their geodiversity. • Soil Water Index (SWI) was calculated from satellite images throughout 1994–2017. • During most of these years, SWI was higher at the heterogeneous hillslopes. • Geodiversity, expressed by stoniness, increases water availability for shrubs. • Numerical simulations of vegetation patches subjected to droughts support this view. [ABSTRACT FROM AUTHOR]

The severe wildfire at Mt. Carmel, Israel, in 2010, caused massive destruction of carbonate rocks. The thermal shock caused extreme exfoliation, producing large and flat clasts, affecting rocks to a depth of up to 20 cm. A decade after the fire, most flakes and spalls disappeared from the rock outcrops and adjacent soils. From these observations, this study pursued two objectives: (a) to monitor and analyze the spatio-temporal distribution of the disintegrated flakes 10 years after the fire and (b) to test the hypothesis that fires contribute to increased soil stoniness via physical and chemical flake erosion. The studied area included five lithostratigraphic units composed of chalk, limestone, and dolomite. The Schmidt Hammer test showed that after a decade, most of the spalled surface on the burned outcrops was lost, exposing new rock surfaces to atmospheric and weathering processes. The spalls and flakes were broken down and pulverized. The most prominent effects were changes in surface stoniness on the rendzina soils over the chalks, while there was less impact on the dolomite and limestone samples. The stoniness of the non-burned chalk was 23–39% and increased significantly to 69–86% in the burned area. Chalk erosion produced large (>16 mm, median 8–16 mm) and abundant gravel, suggesting fragmentation of large spalls, and particles that lost their bladed shapes becoming oblate and equant. While earlier works suggested that increasing rock fragment cover is often associated with the removal of fine particles, our results showed a substantial increase in rock fragments due to fire-induced exfoliation of rock surfaces, leading to long-term changes in soil properties. We therefore propose that the size, shape, and spatial distribution of rock fragments should be considered when examining the effects of rock fragments on hydrological and geomorphological processes or on post-fire soil rehabilitation. Unlabelled Image • Within a decade, the spalling and exfoliation processes following a major fire has nearly ended. • Substantial enrichment in rock fragments occurred leading to changes in soil properties. • The most prominent effects were changes in surface stoniness on the rendzina soils over chalk. • Stoniness of the non-burned chalk was 23–39%, increasing significantly to 69–86% in burned areas. • Spalls were pulverized and particles lost their bladed shapes, becoming oblate and equant. [ABSTRACT FROM AUTHOR]

Research Highlights: Water use efficiency (WUE) varied along a gradient of Juniperus thurifera (L.) forest expansion, being higher in recently colonised areas. Background and Objectives: WUE is a classic physiological process of plants that reflects the compromise between carbon assimilation and water loss and has a profound influence on their performance in water-limited environments. Forest expansion in Mediterranean regions associated with land abandonment can influence the WUE of plants due to the existence of two opposing gradients: one of favourable–unfavourable environmental conditions and another one of increased–decreased intraspecific competition, the former increasing and the latter decreasing towards the expanding front. The main objective of this study was to elucidate how the WUE of Juniperus thurifera varied along the stages of forest expansion and to provide insight on how this variation is influenced by intraspecific competition and abiotic factors. Materials and Methods: Seventeen plots at different distances from the mature forest core were selected at three sites located in the centre of the Iberian Peninsula. For 30 individuals within each plot, we measured biometric characteristics, age, tree vigour, and C/N ratio in leaves, and the leaf carbon isotope signature (δ13C (‰)) as a proxy for WUE. Around each individual, we scored the percentage cover of bare soil, stoniness, conspecifics, and other woody species. Results: WUE of J. thurifera individuals varied along the forest expansion gradient, being greater for the individuals at the expanding front than for those at the mature forest. WUE was influenced by the cover of conspecifics, tree age, and C/N ratio in leaves. This pattern reveals that less favourable environmental conditions (i.e., rocky soils and higher radiation due to lower vegetation cover) and younger trees at the expanding front are associated with increased WUE. The increased cover of conspecifics decreases irradiance at the mature forest, involving milder stress conditions than at the expanding front. Conclusions: Lower WUE in mature forests due to more favourable conditions and higher WUE due to abiotic stress at expanding fronts revealed high constraints on water economy of this tree species in these two contrasting situations. Climate change scenarios bringing increased aridity are a serious threat to Juniperus thurifera forests, affecting both mature and juvenile populations although in different ways, which deserve further research to fully unveil. [ABSTRACT FROM AUTHOR]