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Soil erosion poses a significant threat to agricultural production worldwide, with a still-debated impact on the current increase in atmospheric CO2. Whether erosion acts as a net carbon (C) source or sink also depends on how it influences greenhouse gas (GHG) emissions via its impact on crop yield and nutrient loss. These effects on the environmental impacts of crops remain to be considered. To fill this gap, we combined watershed-scale erosion modeling with life cycle assessment to evaluate the influence of soil erosion on environmental impacts of wheat production in the Ebro River basin in Spain. This study is the very first to address the full GHG balance of erosion including its impact on soil fertility and its feedback on crop yields. Two scenarios were simulated from 1860 to 2005: an eroded basin involving conventional agricultural practices, and a non-eroded basin involving conservation practices such as no-till. Life cycle assessment followed a cradle-to-farm-gate approach with a focus on recent decades (1985–2005). The mean simulated soil erosion of the eroded basin was 2.6 t ha−1 year−1 compared to the non-eroded basin. Simulated soils in both eroded and non-eroded basins lost organic C over time, with the former emitting an additional 55 kg CO2 ha−1 year−1. This net C source represented only 3% of the overall life cycle GHG emissions of wheat grain, while the emissions related to the increase of fertilizer inputs to compensate for N and P losses contributed a similar percentage. Wheat yield was the most influential parameter, being up to 61% higher when implementing conservation practices. Even at the basin scale, erosion did not emerge as a net C sink and increased GHG emissions of wheat by 7–70%. Nonetheless, controlling erosion through soil conservation practices is strongly recommended to preserve soils, increase crop yields, and mitigate GHG emissions. [ABSTRACT FROM AUTHOR]

Prescribed fires are one of the most effective tools to reduce the risk of wildfires but this treatment may negatively affect the hydrological and erosive response of soil, with noticeable increases in surface runoff and soil erosion. Many studies have been published on this matter but there is no consensus in the literature on the magnitude and duration of these effects since the relevant hydrological conditions are site‐specific. Moreover, the relationship between post‐fire hydrology and its main environmental drivers has been little explored. This study has carried out a bibliographic review and a meta‐analysis of the changes resulting from prescribed fire applications (water infiltration, soil water repellency (SWR), surface runoff and soil erosion) using a database of 85 case studies from 41 academic papers that have been published over the last 23 years. The effects of annual precipitation, soil slope, burn severity, fire application season, post‐fire ground cover, and vegetation type on those changes have also been statistically explored. The bibliographic review has revealed that previous case studies have not been equally distributed across the globe but concentrated in only a few countries, mainly the United States and Spain. The meta‐analysis has revealed that (i) water infiltration generally decreases and SWR appears with noticeable increases in surface runoff and soil erosion immediately after the prescribed fire, while the pre‐fire values progressively recover over time; (ii) the window of disturbance in burned soils may last a few months (with some exceptions); (iii) annual precipitation and soil slope significantly influence water infiltration and surface runoff, but not soil erosion, in both the short‐term and medium‐term; (iv) moderate‐to‐high levels of soil burn severity severely enhance surface runoff and soil erosion, and noticeably reduce water infiltration in the short‐term; (v) the level of ground cover burning is important for reducing the runoff rates, but it plays a minor role in water infiltration and soil erosion rates;and (vi) the prescribed fire applied in spring results in lower increases in short‐term runoff and erosion, while fire applications in summer and in shrublands produce the highest increases in soil loss. The following practical recommendations arise from this study: (i) research should be better distributed across all environmental contexts on a global scale; (ii) post‐fire management actions should be immediately implemented after the prescribed fire application; (iii) prescribed fire should be carried out in spring and the soil burn severity should be kept low during burning; (iv) the monitoring studies should be prolonged at least for some years (more than two or three) after prescribed fire; (iv) the catchment‐scale investigations, although more difficult and expensive, should be encouraged (avoiding, however, areas to sparsely burnt in the context of the whole catchment); (v) the monitored variables should also include the most important physical, chemical and biological properties of soil, the cover and structure of regenerating vegetation, as well as the water quality parameters; (vi) the effects of repeated applications of prescribed fire should be experimentally assessed; and (vii) guidelines for standardized and appropriate measurements and analytical methods in experimental activities should be set up. These indications support the use of land managers in the monitoring of the hydrological impacts of the prescribed fire and in the choice of sites where post‐fire management actions must be implemented. The last recommendation of this study is the creation of an experimental database supporting the bibliographic review and the meta‐analysis, which is made available to other researchers and land managers, to create a public, easily‐accessible and comprehensive tool for future research needs and professional use. [ABSTRACT FROM AUTHOR]

Landslide movements and soil loss due to erosion have increased dramatically, causing numerous human and economic losses. Therefore, it is necessary to delimit these risks in order to prevent and mitigate the effects in natural parks of great value, as is the case of the Arribes del Duero Natural Park. As for landslide movements, they are evaluated by estimating the susceptibility to their occurrence, taking into account the different thematic layers: lithology, geomorphology (slopes, curvature, orientations), hydrogeology and vegetation, weighting each of them using the analytical hierarchy method. Then, by means of map algebra, the cartography of susceptibility to landslides is obtained. On the other hand, the RUSLE equation was used to calculate erosive losses. The results of the gravitational susceptibility are grouped into five classes: very high, high, medium, low and very low, so that the first corresponds to areas of high slope, without vegetation, south facing, with a lithology of quartzites, metapelites and gneisses (canyons, sloping valleys) and, on the contrary, the sectors of lower susceptibility coincide with flat areas, more density of vegetation, north facing, with conglomerates, cobbles, sands and clays, corresponding to erosion surfaces or valley bottoms. In terms of erosion results, the greatest losses are found in areas of steep slopes, with little or no vegetation and with poorly developed soils. Finally, taking into account the cartography of landslide risk, the cartography of potential water erosion and land use, it is possible to determine which conservation practices should be carried out, as well as the land uses that are less susceptible to these movements, highlighting in our study the importance of vineyards in their control. [ABSTRACT FROM AUTHOR]

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Biological soil crusts (biocrusts) are communities of microorganisms, fungi, algae, lichens and mosses inhabiting on the soil surface and within the uppermost soil millimetres. They play an important ecological role in drylands, determining physical and chemical soil properties and reducing soil erosion. Studies on biocrust natural recovery establish highly variable recovery times. The different objectives and methodologies of experimentation and analysis, strongly influence these predictions. The main purpose of this research is to analyze the recovery dynamics of four biocrust communities and their relationship with microclimatic variables. In 2004, in Tabernas Desert, some of us removed the biocrust in central 30 cm 30 cm area of three 50 cm x 50 cm plots in each of four biocrust communities (Cyanobacteria, Squamarina, Diploschistes, and Lepraria), installing a microclimatic station in each one with sensors for temperature and humidity of the soil and air, dew point, PAR and rain. Yearly, the 50 cm < 50 cm plots were photographed, and the cover of every species was monitored in every 5 cm <5 cm cell of a 36-cells grid covering the removed central area. We analyzed different functions to fit the cover recovery, the differences in cover recovery speed between communities, the recovery dynamics from the spatial analysis of the plot, the changes in dissimilarity and biodiversity and the possible relationships with the climatic variables. The recovery of the biocrust cover fits to a sigmoidal function. The community dominated by Cyanobacteria developed faster than those dominated by lichens. The Squamarina and Diploschistes communities recovered faster than that of Lepraria and appears to be influenced by the surrounding undisturbed areas. Species-based dissimilarity between consecutive inventories fluctuated and decreased over time, while biodiversity increases in a similar way. The speed of recovery of the biocrust in each community, along with the order in which the species appeared, support the hypothesis about the succession, which would include three phases: firstly Cyanobacteria, then Diploschistes and/or Squamarina and finally Lepraria. The relationship between biocrust recovery and microclimate is complex and this work highlights the need to carry out further research on this topic and on biocrust dynamics in general. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) influence hydrological and erosive processes in drylands, and their effects increase with hypothetic successional development. Runoff and raindrops, both dependent on rain intensity, are among the main causes of erosion in these areas. However, little is known about the existence of soil loss nonlinearity in relation to rain intensity and crust types; this nonlinearity could control biocrust succession and dynamics. The assumption of biocrust types as successional stages, which allow space-for-time sampling, makes it advisable to include all the successional stages when exploring possible nonlinearity. We considered seven types of crusts, three physical and four biological. We created four rainfall intensity levels in controlled laboratory conditions: 18, 60, 120, and 240 mm/h. In all but the last, we conducted the experiments at two levels of antecedent soil moisture. Generalized Lineal Models enabled us to test for differences. These analyses confirmed previous knowledge regarding the significant effect of rainfall intensity, crust type and antecedent soil moisture and their interactions on runoff and soil loss, despite the small sample size of the sample units. For example, runoff, and particularly soil loss, decreased along succession. Moreover, some results were novel: the runoff coefficient increased only up to 120 mm/h of rain intensity. A decoupling between runoff and soil loss occurred at high intensities. Soil loss increased as rainfall intensity increased only up to 60 mm/h, and then it decreased, mainly due to physical crusts, because of the formation of a water sheet on the surface due to the incoming rainwater exceeding the drainage capacity. Although soil loss was greater in the incipient cyanobacteria than in the most developed lichen biocrust (Lepraria community), the protection provided by any biocrust against soil loss was great compared to the physical crust, and almost as strong at all rain intensities. Soil loss increased with antecedent soil moisture only in physical crusts. Biocrusts resisted the rain splash even at a rainfall intensity of 240 mm/h. [ABSTRACT FROM AUTHOR]

The effectiveness of mulching in reducing the risk of erosion has been evaluated in numerous studies. However, its effect on carbon loss has received less attention, despite the potentially negative effects on ecosystem recovery. In this study, the effects of straw helimulching on soil erosion and carbon loss in sediments were investigated after a severe wildfire in NW Spain during the first three years after fire. During the first year after the fire, the accumulated mean sediment yield was 12.4 Mg ha−1 in the control plots and 0.5 Mg ha−1 in the mulched plots. Soil erosion decreased sharply during the second year after the fire and was almost inexistent during the third year after the fire. No differences in carbon concentration were detected between treatments during the period of study. A significantly lower amount of carbon was lost after the mulching treatment due to its effectiveness in reducing sediment erosion. The mulching treatment did not significantly influence the amount of carbon sequestered in the vegetation. Although the application of mulch did not affect carbon fixation in vegetation, its application after fire can be considered a sustainable way of managing forest ecosystems to reduce the impact of fire on carbon emissions. [ABSTRACT FROM AUTHOR]

The frequency and magnitude of flash floods in the olive orchards of southern Spain have increased because of climate change and unsustainable olive-growing techniques. Affected surfaces occupy > 85 % of the rural regions of the Upper Guadalquivir Basin. Dangerous geomorphic processes record the increase of runoff, soil loss and streamflow through time. We report on ripple/dune growth over a plane bed on overland flows, deep incision of ephemeral gullies in olive groves and rock-bed erosion in streams, showing an extraordinary sediment transport capacity of sub-daily pluvial floods. We develop a novel method to design optimal solutions for natural flood management and erosion risk mitigation. We adopt physical-based equations and build a whole-system model that accurately reproduces the named processes. The approach yields the optimal targeted locations of nature-based solutions (NbSs) for active flow-control by choosing the physical-model parameters that minimise the peak discharge and the erosion-prone area, maximising the soil infiltration capacity. The sub-metric spatial resolution used to resolve microtopographic features of terrains/NbS yields a computational mesh with millions of cells, requiring a Graphics Processing Unit (GPU) to run massive numerical simulations. Our study could contribute to developing principles and standards for agricultural-management initiatives using NbSs in Mediterranean olive and vineyard orchards. [ABSTRACT FROM AUTHOR]

The olive groves' relevance has historically been ingrained in Mediterranean cultures. Spain stands out as a leading producer worldwide, where olive trees are extensively grown in the Andalusian region. However, despite the importance of this strategic agricultural sector, cultivation through the years has given rise to various crop management practices that have led to disruptive erosion processes. The objective is to measure land erosion in over 100-year-old olive groves considering the 3D reconstructed recent relief of olive tree mounds. A time-of-flight depth sensor, namely, Kinect v2, was employed to 3D model the target areas, i.e., trunk and exposed roots, to determine the height as a surrogate of the difference between the historical and recent relief. In three plots in southern Spain, the height of relic tree mounds was measured in olive trees at the upper and bottom parts to determine soil profile truncation. The results were compared and validated with manual measurements (ground truth values). Olive trees were grouped into high, moderate, and low slope gradient classes. The results showed, in all cases, high consistency in the correlation equations (Pearson's coefficients over 0.95) between the estimated values in the models and the actual values measured in the olive trees. Consequently, these excellent results indicate the potential of this low-budget system for the study of historical erosion. Notably, the Kinect v2 can generate 3D reconstructions of tree mounds at microtopographic scales in outdoor situations that would be challenging for other depth cameras under variable lighting conditions, as found outdoors. [ABSTRACT FROM AUTHOR]

We used wind-transported particle collectors of our own inhouse design to monitor the sediment flow in a citrus orchard in Southeast Spain. These collectors, which can differentiate sediment collected by direction of origin, are very efficient, economical, and easy to manufacture from thermoplastic filaments with an industrial 3D printer. Data were acquired from six vaned masts, each with four collectors at different heights, and on one of those masts, the collectors included load cells with one end attached to the collector floor and the other end to each oriented compartment in the collectors. The load cell values were interpreted in real time by a microcontroller and amplifier. The remote monitoring system was developed with an internet of things (IoT) platform. The results showed clear predominance of winds from the Northeast after dark, and from the South during the middle of the day. After analyzing the sediment transport rates and their balance, we found that those being deposited in the citrus orchard from the Northeast had a higher carbonate content (mainly calcite), which had an aggregating and therefore stabilizing effect against wind erosion of the soil. Furthermore, significant amounts of highly adhesive phyllosilicates were captured by the upper traps, which also contributed to reducing soil wind erodibility because of their adhesiveness. However, the sediments from the South with much more total transported mass were not deposited in the study zone, but leeward of it and contained a large amount of quartz, promoting abrasion and increasing wind erodibility of the soil. [ABSTRACT FROM AUTHOR]

Authors propose a beneficial methodology for hydrological planning in their study. Prospective evaluations of the basins' net capacity can be done using the technique presented. The HEC-HMS (Hydrologic Modelling System) software can be used to estimate in a basin, the sediment emitted. For a certain precipitation, this methodology allows estimating, within a certain range, the gradual blockage of a reservoir, and even a projected date for total blockage. This has some applications to adopt corrective measures that prevent or delay the planned blockage deadlines. The model is of the semi-distributed type, estimating the generation and emission of sediments by sub-basins. The integration of different return periods in HEC-HMS with a semi-distributed model by sub-basins and the application of a mathematical model are the differentiating element of this research. The novelty of this work is to allow prognosing the reservoir sedimentation rate of basins in a local and regional scale with a medium and large temporary framework. The developed methodology allows public institutions to take decisions concerning hydrological planning. It has been applied to the case of "Charco Redondo" reservoir, in Cádiz, Andalusia, in southern Spain. Applying the methodology to this case, an average soil degradation of the reservoir basin has been estimated. Therefore, it is verified that in 50 years the reservoir is expected to lose 8.4% of its capacity. [ABSTRACT FROM AUTHOR]

• We compare soil redistribution rates estimated by both 239+240Pu and WaTEM/SEDEM. • Rates estimated by the two methods show important discrepancies. • These discrepancies help us understand the limitations of each method. • Less uncertain conditions are needed to validate the 239+240Pu method. • Both methods predict severe soil degradation in the next decades. Soil redistribution by water and tillage soil erosion has a profound effect on the spatial variability of soil security indicators. In this study, we assess the potential of estimating long-term soil redistribution rates across a Mediterranean olive orchard catchment using two methods: 239+240Pu and the WaTEM/SEDEM model. Additionally, we identify potential sources of uncertainty explain result discrepancies, and offer guidance for reducing uncertainty. Soil sampling points were taken both in the inter-row areas and below the tree canopies and 239+240Pu inventories were converted into soil redistribution rates using MODERN. Sediment yield data measured in the catchment outlet is used to calibrate WaTEM/SEDEM. The results show a poor agreement between both methods. In this sense, these results indicate that both methods are considerably affected by several sources of uncertainty, both inherent to the methods themselves and related to the specific conditions of the study area. The latter are mainly related to anthropogenic changes in the soil surface related to soil tillage and rill filling practices and an important past land leveling effect. Despite the discrepancies, both methods convey a similar overarching message: soil security and olive production can be highly threatened in the Mediterranean in the next decades. This study demonstrates the potential advantages of combining FRN-based estimates and model simulations and highlights the importance of selecting an appropriate study area in this type of studies and the need to recognize associated uncertainties when estimating soil redistribution rates, whether employing FRN-based or modelling methods. [ABSTRACT FROM AUTHOR]

Human activities have caused a significant change in the function and services that ecosystems have provided to society since historical times. In mountainous landscapes, the regulation of services such as water quality or erosion control has been impacted by land use and land cover (LULC) changes, especially the loss and fragmentation of forest patches. In this work, we develop a Remote Sensing (RS)-based modelling approach to identify areas for the implementation of nature-based solutions (NBS) (i.e., natural forest conservation and restoration) that allow reducing the vulnerability of aquatic ecosystems to siltation in mountainous regions. We used time series Landsat 5TM, 7ETM+, 8OLI and Sentinel 2A/2B MSI (S2) imagery to map forest dynamics and wetland distribution in Picos de Europa National Park (Cantabrian Mountains, northern Spain). We fed RS-based models with detailed in situ information based on photo-interpretation and fieldwork completed from 2017 to 2021. We estimated a forest cover increase rate of 2 ha/year comparing current and past LULC maps against external validation data. We applied this forest gain to a scenario generator model to derive a 30-year future LULC map that defines the potential forest extent for the study area in 2049. We then modelled the distribution of wetlands to identify the areas with the greatest potential for moisture accumulation. We used an S2 mosaic and topography-derived data such as the slope and topographic wetness index (TWI), which indicate terrain water accumulation. Overall accuracy scores reached values of 86% for LULC classification and 61% for wetland mapping. At the same time, we obtained the potential erosion using the NetMap software to identify potential sediment production, transport and deposition areas. Finally, forest dynamics, wetland distribution and potential erosion were combined in a multi-criteria analysis aiming to reduce the amount of sediment reaching selected wetlands. We achieved this by identifying the most suitable locations for the conservation and restoration of natural forests on slopes and in riparian areas, which may reduce the risk of soil erosion and maximise sediment filtering, respectively. The results show a network pattern for forest management that would allow for controlling erosion effects across space and time at three levels: one, by reducing the load that originates upslope in the absence of forest cover; two, by intersecting runoff at watercourses related to sediment transport; and three, by a lack of former barriers, by trapping erosion near to the receiving wetland systems, main river axes and contributing streams. In conclusion, the proposed methodology, which could be transferred to other mountain regions, allows to optimise investment for erosion prevention and wetland conservation by using only very specific areas of the landscape for habitat management (e.g., for NBS implementation). [ABSTRACT FROM AUTHOR]

Less attention has been paid to runoff generation from semi‐arid than from humid‐temperate catchments. The SCS curve number approach is simple to apply and widely used, but lacks physical underpinning. Here output from a runoff generation models is compared with data from field measurements, making use of 11 years data from rainfall and runoff events at the Sierra de Enguera Soil Erosion Experimental Station in Eastern Spain. Runoff from natural rainfall events was monitored for 10 years on bare plots of 1–16 m length. The largest storm event was of 142 mm, generating runoff of up to 115 mm on the smallest plots. The model presented simulates overland storm flow on a sloping rough and unvegetated surface, representing an area of 320 × 320 m. Green‐Ampt infiltration constants are randomly assigned to each cell in a 128 × 128 grid, and rectangular storms applied at a range of total amounts and intensities to simulate runoff at each transect across the area. A simple algebraic expression is developed to estimate total runoff and storage in terms of storm size and duration, and plot length, with parameters that reflect infiltration behaviour, and this expression is compared with the SCS curve number approach. For the very largest storms, both expressions converge asymptotically towards 100% runoff, but the revised expression greatly improves estimates of runoff from smaller events. Output of these simulations is compared with measured storm runoff data on bare runoff plots at the Sierra de Enguera experimental Station in SE Spain and gives further support to the proposed expression for storm runoff. [ABSTRACT FROM AUTHOR]

• The cleaning schedule of a 1 MW PV site is optimized using environmental data only. • A cleaning threshold of 1 mm/h returns the best results for the investigated site. • Despite the optimization, a fixed cleaning threshold might not be always accurate. • Rain and particulate matter are used to model soiling with an error of 0.022. • The seasonality allows minimizing the loss by cleaning on the same day every year. This work investigates the possibility of using historical environmental parameter data to predict the typical soiling loss profile and the most convenient cleaning schedule for a PV site. The three-year performance of a 1 MW system in Southern Spain is evaluated using different soiling extraction methods. When the rainfall pattern is used to detect natural cleaning events, the best results are obtained if a 1.0 mm/hour threshold is considered. However, despite the optimization, setting a fixed threshold is found to lead occasionally to the over- or under-detection of cleaning events. Similar trends in the modelling results are found if the thresholds are set using the maximum hourly or the cumulative daily rainfall data, but the errors and the optimal values change depending on the rainfall dataset. The study also shows that a soiling extraction method based only on precipitation and particulate matter, calibrated against one year of PV data, is able to generate a soiling profile with a mean absolute error of 0.022 and to recommend a cleaning day within a week of the actual optimal dates. This will make it possible to estimate the soiling losses and the optimal cleaning schedule for a PV site even if no power data are available. [ABSTRACT FROM AUTHOR]

Phytoliths are plant microfossils commonly used as qualitative archive markers in archaeological and paleoecological studies. Their potential uniqueness to the vegetation cover, robustness to weathering, and lack of chemical alteration along the transport paths make them potentially suitable tracers for quantitative erosion studies. In this pilot study, we explore the potential of phytoliths in a sediment fingerprinting study in the Ceguera catchment (28 km2) in NE Spain. The phytolith concentrations and morphologies of four land cover classes (agricultural land, badland, forest, and shrubland) were analysed, and their contributions to four natural sediment mixture samples along the river course were modelled. Phytolith concentrations allowed us to discriminate sources sufficiently, albeit with limited sample size. The performance of the phytoliths as tracer was tested by reproducing the sources of artificial sediment mixture samples with satisfactory recall ratio. Results identified badlands to be the main contributor, with 84–96% of the sediment load to the sinks, followed by shrublands (median 5%) and agricultural lands (median 2%). These major findings can be reproduced by other conventional erosion studies from this area, indicating that phytoliths are suited to quantifying erosion patterns in mesoscale catchments. [ABSTRACT FROM AUTHOR]

• The long-term observed sediment yield of forests is lower than reported so far. • The index of connectivity (IC) was calculated using vegetation as target sinks. • Subplot sediment yields did not correlate with vegetation cover. • They significantly correlated with IC and its hot/cold spots relative areas. • The important roles of structural and functional connectivity are highlighted. Semi-arid (semi-)natural terrestrial ecosystems are often vulnerable to soil erosion, but long-term comparable observations are relatively scarce. We measured erosion for thirteen years on a hillslope dominated by tussock grass and pine trees in the Mediterranean region and conducted multiple aerial surveys of landscapes. At plot scales, we found sediment yields of 3.1 g m−2 yr−1 for open forest, and around 35 g m−2 yr−1 for tussock grasslands, probably attributed to differences in vegetation type and cover related to exposition. Furthermore, erosion rates in the forest were lower than reported so far. The values obtained could act as a baseline for achieving land degradation neutrality. The tussock grass plots were divided into ten natural subplots. Subplot sediment yields were not sensitive to vegetation cover but significantly negatively correlated with the maximum value of the index of connectivity (IC). This metric, calculated for bare areas not directly connected to measurement gutters for subplots, measures structural connectivity between bare areas and vegetation. Furthermore, spatial clusters of high and low connectivity - hot and cold spots of IC were identified. Sediment yields decreased significantly with a higher percentage of IC hot spots in bare areas, due to vegetation obstruction. However, sediment yields increased significantly with the relative area of IC cold spots plus bare areas adjacent to gutters, which could be useful hints for functional connectivity. At broader catchment scales, the IC cold spot showed promise in identifying potential sediment sources, demonstrating its stability and potential in the upscaling analysis. Our findings support the role of vegetation and topography and the importance of structural and functional connectivity in erosional processes. [ABSTRACT FROM AUTHOR]

The rainfed mountain plantations in semiarid areas of the Mediterranean region with conventional practices register soil erosion values much higher than soil formation rates, affecting their long-term sustainability. The objective of this study during four-year monitoring period was to evaluate the response of soil erosion and runoff to different soil-management strategies (SMS) for the most representative rainfed fruit crops: almond, olive, and vineyard. The SMS based on conservation agriculture techniques were: minimum tillage, minimum tillage with plant strips, and no-tillage with plant strips. Soil erosion and runoff patterns were examined in erosion plots on a mountain slope under each SMS. The results demonstrated that the SMS investigated reduce runoff and soil erosion compared to conventional tillage in the study area. The combination of minimum tillage with plant strips in almond and vineyard showed to be more valuable strategy in soil control than unique minimum tillage, averaging a reduction of soil erosion and runoff of 36 and 39%, respectively. As for olive, the minimum tillage with plant strips with respect to no-tillage was able to lessen both soil erosion and runoff by 36%. Likewise, this strategy proved to be the most efficient for minimizing the adverse impact of heavy rains on water erosion development on hillslopes. Since an increase of high-intensity rainfalls in the Mediterranean semi-arid areas is expected, the implementation of sustainable strategies is urgent in order to mitigate the effects of climate change. [ABSTRACT FROM AUTHOR]

The impact of climate change on future soil loss is commonly assessed with soil erosion models, which are suggested to be an important source of uncertainty. Here, we present a novel soil erosion model ensemble to assess model uncertainty in climate‐change impact assessments. The model ensemble consists of five continuous process‐based soil erosion models that run at a daily time step (i.e., DHSVM, HSPF, INCA, MMF, SHETRAN). The models were implemented in the SPHY hydrological model and simulate detachment by raindrop impact, detachment by runoff, and immediate deposition. The soil erosion model ensemble was applied in a semiarid catchment in the southeast of Spain. We applied three future climate scenarios based on global mean temperature rise (+1.5, +2 and +3°C). Data from two contrasting regional climate models were used to assess how an increase and a decrease in projected extreme precipitation affect model uncertainty. Soil loss is projected to increase (up to 95%) and decrease (up to −30%) under climate change, mostly reflecting the change in extreme precipitation. Model uncertainty is found to increase with increasing slope, extreme precipitation and runoff, which reveals some inherent differences in model assumptions among the five models. Moreover, the model uncertainty increases in all climate change scenarios, independent of the projected change in annual precipitation and extreme precipitation. This stresses the importance to consider model uncertainty through model ensembles of climate, hydrology, and soil erosion in climate‐change impact assessments. [ABSTRACT FROM AUTHOR]

Slope stabilization treatments like mulching are commonly used to reduce runoff and erosion after high severity wildfires. Agricultural straw is the most common material although it is susceptible to be blown away by the wind or introduce non-native plants. Although these limitations do not apply to wood-based mulch, this material has not been widely tested in the field. We compared the efficacy of two types of mulch for reducing soil erosion and evaluated its effects on vegetation recovery during the first two years after wildfire. The treatments were: straw helimuching (3.0–3.5 Mg ha−1), ground-applied wood strand mulching (11 Mg ha−1) and control (no mulch). During the first year after wildfire, the mean sediment yield in the control plots was 11 Mg ha−1. In this period, the respective mean sediment yields in the wood strand mulched plots were significantly lower than in the control plots (1.6 Mg ha−1) but higher than in the straw mulched plots (0.5 Mg ha−1). Soil erosion decreased during the second year after wildfire in all cases, while vegetation cover and soil penetration resistance and soil shear strength increased. Neither of the mulching treatments significantly affected the recovery of vegetation cover or species composition. The results indicate the feasibility of wood strand mulch to effectively reduce soil erosion after the fire, with no detrimental effects on vegetation recovery. However, the amount of material required to ensure the protection of the soil, together with difficulties to be applied, may limit its widespread use as a post-fire soil stabilization option. [ABSTRACT FROM AUTHOR]

This research offers a quantitative study of the hydrological and erosive effects of an extreme stormy event (62mm in one hour) in Barranco de la Casa de la Parra basin, an almond tree steppe. The drainage basin and the synoptic situation are characterized. For hydrological quantification, the rational method has been used according to Standard 5.2-IC of the Ministry of Development (Government of Spain), for a return period of 25 years. The erosive dynamics have been quantified through field measurements of a large gully originated by hydrological processes. The results consist of the measurement of hydrological variables that characterize the flash flood, as well as the estimate consequent loss of soil, both in volume and weight. We highlight a peak flow rate of 18m3/s able to excavate 1741m3 of materials. The results are interpreted as being a consequence of the type of soil (sedimentary basin) and the current main land use (almond trees), which unprotects the soil more and longer than the traditional uses (scrubland and a larger surface of cereals). It concludes by drawing attention to the apparent low sensitivity of the agrarian sector towards extreme erosion processes, which seem to be, in accordance with these results and with scientific literature, those that most intensely reconfigure the landscape in a scenario of agro-natural imbalance. [ABSTRACT FROM AUTHOR]

Climate change projections over the Mediterranean basin point toward an increase in frequency and intensity of extreme events that will directly impact ecosystems resilience. In this study, we evaluated future trends of soil loss in forestland in Catalonia (NE Spain) due to fires and vegetation dynamics, considering the potential future impacts of co‐occurring extreme fire and rainfall events, and assessing how fire suppression can contribute to soil erosion mitigation. The process‐based MEDFIRE model was used to simulate changes in forestland due to climate and fires between 2011 and 2050 under six different future scenarios that resulted from the combination of two climatic scenarios and three fire management policies. Annual projections on landscape changes were used to estimate soil loss using the Universal Soil Loss Equation. Projected annual soil losses for forested land in Catalonia ranged between 15 and 16 tons/ha, with scenarios simulating current levels of fire suppression projecting around −5% soil loss than those assuming more relaxed suppression strategies. On average, fires explained 12–16% of annual soil loss in the region, but in fire‐severe years, they explained up to 90% of the total annual soil loss. Projected mean total soil loss in years where extreme rainfall and fire meet was 150% higher than in years where both events were not contemporary. The estimated annual probability that the two extreme impacts will co‐occur in the future ranged between 0.09 and 0.11 between scenarios. Our results highlight the importance of landscape and fire management in minimizing soil loss and its potential impacts for ecosystems. [ABSTRACT FROM AUTHOR]

Gully erosion is one of the main processes of soil degradation, reaching 50%–90% of total erosion in basins. As erosion processes are related to rainfall regime, the depletion and deposition rates can be increasing in a climate change scenario. This paper deals with the quantification of erosion processes in an active gully affecting olive groves of the province of Jaén (southern Spain), using geomatics techniques (photogrammetry and LiDAR). Eight historical aerial flights from 1980 to 2016, a LiDAR dataset (2014) and 2 recent UAS surveys (2019–2020) were used and processed in a common reference system with the support of field GNSS ground control points. Then, DSMs and orthophotographs were obtained and DSMs of differences (DoDs) calculated, from which we can identify gullies, calculate the depletion and deposition areas, and estimate height differences and volumes involved. These analyses result in an average depletion of about −1.6 m (incision) and a waste volume up to 30000 m3 (soil losses), which lead to a rates of −0.05 m/year and −44 t/ha*year, respectively. These rates are very different along the considered periods, reaching the maximum values (near −300–450 t/ha*year) in 2009–2011 and 2011–2013, coinciding with the periods of higher rainfall in the last fifty years, that probably have underwent an increase of 10–30% in the last decades. Thus, the evolution of the gully area for 40 years has been analysed in relation to the rainfall regime that has been established from the daily rainfall data. [ABSTRACT FROM AUTHOR]

During the first part of the 21st century, the Spanish territory has experienced a considerable increase in the artificial surface in its various aspects: urbanization, commerce, services, communication routes, etc., which means loss of natural soil, landscape diversity and resources. The coastal spaces have been strongly affected by this process. In this paper we want to show the evolution of the changes in the land uses in the Spanish coast, both in the peninsula and in the islands, particularly in the first line (first 0 to10 kilometers). The urban structure (artificial land) before and after the economic crisis of 2008 helps to understand the situation of territorial saturation experienced by the coastal area in Spain, mainly due to tourism activity and the evolution of destinations coastlines both in terms of urbanization growth and the creation of leisure spaces complementary to traditional sun and beach tourism. The data from SIOSE have been used to build the cartography and achieve the analysis. [ABSTRACT FROM AUTHOR]

Soil erosion can potentially threaten different resources inside and outside of burned areas, and the risk of water becoming contaminated with sediment may be particularly severe. Various postfire actions, such as applying straw mulch, have been carried out in northwestern Spain in recent years with the aim of mitigating the risk of soil erosion. Nonetheless, because of the short interval between summer wildfire and autumn rains, careful selection and prioritization of the areas to be treated is crucial. Changes in hydrological connectivity could be measured and used as a criterion for selecting such areas. However, studies addressing changes in hydrological connectivity as a consequence of forest fires are scarce. In the present study, we assessed the effects of fire and postfire helimulching on the hydrological connectivity and sediment loads in a forest catchment burned by a wildfire in August 2016. Sediment yields were recorded in 20 plots (180 m2). Hydrological connectivity was computed with a version of the Borselli index and two alternative weighting factors: the C factor from the Revised Universal Soil Loss Equation and a factor based on field surveys of soil burn severity. The effect of mulching was also considered. The results indicate that the version of the Borselli index based on field measurements of soil burn severity best reflects the susceptibility to postfire sediment delivery. Moreover, this method was also suitable for evaluating the effect of mulching on soil erosion. The study findings may help forest managers to plan postfire actions. [ABSTRACT FROM AUTHOR]

Climate models project increased extreme precipitation for the coming decades, which may lead to higher soil erosion in many locations worldwide. Different soil erosion model concepts are used to assess the impact of climate change on soil erosion at large spatial scales, including models forced by precipitation and by runoff. However, there is little knowledge of the implications of soil erosion model conceptualization on projected soil erosion rates under climate change. Here, we assess the impact of climate change with the three most widely used soil erosion model concepts: a model forced by precipitation (RUSLE); a model forced by runoff (MUSLE); and a model forced by precipitation and runoff (MMF). We applied the models to two contrasting Mediterranean catchments (south-east Spain), where climate change is projected to decrease the annual precipitation sum and increase extreme precipitation, based on the RCP8.5 climate change scenario. Depending on the model, soil erosion is projected to decrease (RUSLE) or increase (MUSLE and MMF) in the study area. Although it is difficult to validate future model projections, the differences between the model projections are, inherently, a result of their model conceptualization: a decrease in soil loss due to a decrease in the annual precipitation sum (RUSLE); and an increase in soil loss due to an increase in extreme precipitation and, consequently, increased runoff (MUSLE). An intermediate result is obtained with MMF, in which a projected decrease in detachment by raindrop impact is counteracted by a projected increase in detachment by runoff. We conclude that in climate change impact assessments it is important to select a soil erosion model that is forced by both precipitation and runoff, which under climate change may have a contrasting effect on soil erosion. [ABSTRACT FROM AUTHOR]

Concentrated erosion, a major feature of land degradation, represents a serious problem for soil and water resources management and a threat to ecosystems. Understanding the internal mechanisms (de‐)coupling sediment pathways can improve the management and resilience of catchments. In this study, concentrated erosion and deposition forms were mapped accurately through field and aerial unmanned aerial vehicle (UAV) campaigns, in order to assess the evolution of connectivity pathways over a series of three contrasted and consecutive flood events occurring between October 2016 and January 2017 (return period ranging from 0.5 to 25 years) in a small Mediterranean agricultural catchment (Can Revull, Mallorca, Spain; 1.4 km2). In addition, a morphometric index of connectivity (IC) was used to identify the potential trajectories of different concentrated erosion forms and deposition areas. IC predictions were calibrated by identifying the optimal critical thresholds, i.e. those most consistent with field observations after each of the events studied. The results found that the index performed well in predicting the occurrence and the length/area of the different type of landforms, giving kappa (κ) coefficients of variation ranging between 0.21 and 0.92 and linear correlations R2 between 0.33 and 0.72. The type of landform affected the correspondence of IC predictions and field observations, with lower thresholds the greater the magnitude of their associated geomorphic processes. Rainfall magnitude proved to be a very important factor controlling the development of erosion and deposition landforms, with large differences in length/area between the contrasted events. The evolution of the observed trajectories revealed feedback dynamics between the structural and functional connectivity of the catchment, in which morphological changes determined the spatial distribution of the processes' activity in the successive events and vice versa. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Persimmons (Diospyros kaki) are trees cultivated under subtropical environmental conditions but are also found in other regions such as the Mediterranean. However, no research has been conducted to investigate soil erosion processes under Mediterranean soil management systems characterized by flood irrigation and/or tillage. The Improved Stock Unearthing Method (ISUM) for assessing long‐term soil mobilization was applied to two fields, one under tillage and the other under no‐till with herbicide within a 25‐year old Mediterranean persimmon plantation. Replicating methods used in vineyard studies, graft unións on persimmon plants were used as passive bio‐indicators of soil surface changes in this study. The tilled field showed a total soil mobilization volume of 48.4 m3 on a 408.5 m2 plot, representing a total soil loss of 52.6 Mg ha‐1 yr‐1. For the plot (468 m2) managed with no‐till and herbicide, the results indicated total soil mobilization of 33.6 m3 which translates to 31.9 Mg ha‐1 yr‐1. It is concluded that flood irrigation is able to modify the runoff pathways and landforms in Mediterranean persimmon plantations, and the flood impact is more extensive when combined with tillage. For the first time, ISUM has been successfully applied to estimate soil erosion in a plantation under flood irrigation. [ABSTRACT FROM AUTHOR]

In agricultural lands, the way in which slope position affects the detachment of material and the runoff generation is not clear. There are complex interactions between slope position, slope gradient and a series of soil characteristics, and their impact on runoff generation and soil erosion may vary from site to site. We designed an experiment to investigate the initial hydrological responces of soils located on different slope positions (footslope, backslope and shoulder) in runoff and soil detachment generation. To achieve these goals, 25 high-intensity low frequency rainfall events were simulated in experiments with a return period of 5 years, on 0.25 m2 circular plots to measure the detachment along a hillslope in the Celler del Roure vineyards in Eastern Spain. The results of this investigation showed that soil erosion rates (3 Mg ha−1 h−1) were high and there were no significant differences between sites in relation to slope position; all the plots generated runoff (runoff coefficient of 24.8%). These results allow us to conclude that soil detachment and runoff generation in Mediterranean vineyards, where tillage is millennia-old management practice, could be also evenly distributed. Therefore, the used management practices in these vineyards contribute to creating net source areas of runoff and erosion with no areas that could act as a sink under intensive rainfall events. Based on our research and a literature review, we propose to implement nature-based solutions that would contribute to reducing soil erosion in agricultural land by creating sink areas in the form of hedgerows, ponds, or vegetation strips where the surface wash deposits and water can sediment and infiltrate. We also discussed other management practices contributing to reduction of erosion,such as mulching and inter-row crops. We state that there is an urgent need to apply strategies to reduce soil loss in vineyards. [ABSTRACT FROM AUTHOR]

Purpose: Soil erosion is one of the most detrimental consequences of forest fires. The present study aimed to compare the effectiveness of helimulching and needle cast for reducing soil loss after wildfire in NW Spain. Materials and methods: Sediment yields were determined during the first 2 years after fire in 30 plots (80 m2) established in an area affected by wildfire in the summer of 2015. Thus, 10 plots were established for monitoring each of the following treatments: combusted canopy, combusted canopy + helimulching and scorched canopy. The effect of each type of treatment on soil erosion was tested using a general linear mixed model. Results and discussion: Immediately after helimulching, the mean soil cover was 90%, whereas the fallen needles from the scorched trees totally covered the burned soil. Soil erosion was significantly higher in the combusted canopy treatment than that in the combusted canopy + helimulching and scorched canopy treatments. The latter two treatments yielded similar results (0.3 and 0.5 Mg ha−1, respectively). The similarity in effectiveness is probably due to the similar initial degree of soil cover provided by both treatments. Conclusions: Needle cast from totally scorched crowns significantly reduced soil erosion after wildfire. Helimulching resembled the effects of the litter fallen from the scorched trees with a similar reduction in soil loss. [ABSTRACT FROM AUTHOR]

Olive (Olea europaea L.) is one of the main crops in the Mediterranean area, with Spain leading its production. The majority of the plantations are on rainfed land, poor soils with steep slopes. Regarding to soil, tillage (T) is the main management system used by farmers. Consequently, erosion and the resulting soil organic carbon (SOC) losses associated to it are one of the main environmental problems of olive production. Conservation Agriculture (CA) practices in permanent crops comprise the sowing of groundcovers or cover crops (CC) between the rows of olive trees. CC protect the olive orchard from erosion, preventing soil degradation. However, the relationship between the erosion and SOC losses under CC and T need to be better understood. In a four-year period (2003–2007) water, soil and SOC losses by erosion were measured in micro-plots (1 ×1 m2) that were managed with T and CC in eight study zones in Andalusia (Southern Spain). At the same time, the characteristics of all rainfall events during the study period were registered, and soil cover was estimated from images taken during the field campaigns. SOC output was observed to be statistically positively correlated to runoff and erosion. The loss of water, SOC and sediment were mainly affected by the characteristics of the rainfall events and soil cover. The type of soil or the typology of the olive grove plantation were not so important for the loss of SOC under conservation agriculture management. However, these facts were especially significant for the T conditions. Conversely to T, where only 22.4 % of soil was protected, CC provided a 65.7 % cover throughout the season. This better protection of the soil provided by the CC, resulted in a lower influence of the rainfall events in the loss of water, soil and SOC. This was not the case in the T systems. The conservation management was responsible for a 36.7 % average reduction in runoff and an 85.5 % reduction in erosion compared to T, which decreased SOC loss associated with sediment by 76.4 %. • Cover crops increased soil cover and reduced runoff (37.6 %) and erosion (85.6 %). • Cover crops made that SOC were less dependent of the rain characteristics than tillage. • The poorest soils presented higher erosive rates and increased the C enrichment ratio. • Cover crops reduced three quarters the loss of SOC respect to tillage. [ABSTRACT FROM AUTHOR]

To get a full understanding of the impacts of global change on the catchment-scale sediment balance, models are needed that combine hillslope soil erosion processes with channel morphodynamics. Here we present a modification to the SPHY-MMF model that includes a novel channel morphodynamics module, which determines erosion and deposition in rills and channels. We applied the model to a Mediterranean study area in southeast Spain, in which we show that channel erosion contributes substantially (35%–40%) to the total sediment yield, highlighting the importance of accounting for channel erosion in catchment-scale sediment budget estimations. The climate change scenarios show that the different erosional processes (i.e. sheet, rill, channel) are projected to decrease or increase, depending on the projected change in annual and extreme precipitation. From this we conclude that interactions between different erosional and depositional processes should be considered when studying the impact of global change on the catchment-scale sediment balance. [Display omitted] • We present a novel channel morphodynamics module for the SPHY-MMF model. • The new module determines erosion and deposition in rills and channels. • We assessed the impacts of land use and climate change on the sediment balance. • Channel erosion contributes substantially (35%–40%) to the catchment sediment yield. • Differences in future annual and extreme precipitation control the sediment balance. [ABSTRACT FROM AUTHOR]

The Mediterranean region is a climate change hotspot due to projected precipitation decreases, soil erosion, and rising temperatures in the coming decades. In such a context, wheat productivity is expected to decrease; thus, all available croplands will need to be farmed to meet food demands. It is therefore crucial to have adequate management to help balance wheat production and environmental protection in specific target environments. With this aim, we present a study in Castile and Leon (Spain) in which we assess conventional and certified organic wheat grain yield and quality. Moreover, we spatially define wheat cultivation suitability categories and monitor crop rotation practices. For wheat suitability mapping, a fuzzy interference system was used to standardize topographic (height and slope), edaphic (pH, soil erosion, organic matter, and texture), and climatic (rainfall and temperature) variables and create marginal, suitable, and very suitable wheat cultivation suitability categories. We calculated the area of wheat suitability categories with confidence intervals and discussed factors affecting productivity. Additionally, we assessed the performance of certified organic and conventionally managed fields with organic and chemical fertilization. We also examined crop rotations using Sentinel-2 data over two seasons (2020−21). Certified organic management yielded 50% less than conventional management in similar environments while maintaining grain quality. Besides management, the main causes of the yield gap are the growing environment and variety. In conventional wheat management, organic fertilization achieves comparable yields to chemical fertilization. Crop rotation practices are uncommon, and over 50% of fields rotate wheat-to-barley or wheat-to-wheat, indicating poor soil management. The region has 25% of cropland classified as marginal wheat croplands (163,503 ± 33,796 ha) producing <2500 kg/ha. Wheat organic agriculture has decreased yield gaps in marginal croplands compared to more productive areas. By farming organic wheat in marginal croplands, the best croplands might be used for more productive farming. • The studied region in Spain has 25% of cropland classified as marginal wheat croplands. • A fuzzy interference system has proven effective to decipher wheat suitability classes. • Sentinel-2 data allowed monitoring the uncommon crop rotation practices in the region. • Certified organic management yielded 50% less than conventional in similar settings. • Wheat organic agriculture has decreased yield gaps in marginal croplands. [ABSTRACT FROM AUTHOR]

Changes in land use are common in Mediterranean areas and are reported as having produced changes in the intensity of soil erosion. Dehesas are rangelands with a disperse tree cover, widespread in the south‐western part of the Iberian Peninsula and similar ecosystems are also common in other areas with a Mediterranean climate. The aim of the present study is to analyse temporal and spatial variations of soil erosion rates estimated along three hillsides, located in two farms (Buitrera and Parapuños) in southwest Spain. To understand the temporal variation, soil erosion rates were studied in light of land use‐management changes that took place during the last few centuries. Results indicate very low erosion rates prior to the 18th century in both farms. In Buitrera, a first increase of soil loss rates was identified during the period 1831‐1897, amounting to 7.4 t ha‐1 y‐1. A further increase took place during the 20th century, reaching a mean erosion rate of 29.1 t ha‐1 y‐1. In Parapuños, data points to a significant increase from 1881 onwards, with an estimated mean erosion rate of 18.5 t ha‐1 y‐1. Those increases were presumably connected with an intensification of land use, such as cultivation and excessive livestock populations. Regarding spatial variation, the bare surface and the erosive power of run‐off along the hillsides accounts for 76% of the soil erosion rates dispersion. At a local scale, the variability of erosion rates could not be explained, because of (i) uncertainty related to the micromorphology of the past soil surface and (ii) the role of tillage erosion in the past. However, the results obtained offer valuable data on the temporal and spatial variation of erosion rates in dehesas at the hillslope scale and a similar approach could be used for other rangelands with a disperse tree cover. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation on the spectral losses of photovoltaic (PV) soiling. The transmittance of a glass coupon exposed to natural soiling outdoors in Jaén, southern Spain, has been measured weekly and used to estimate the soiling losses that various types of photovoltaic materials would experience if installed in the same location. The results suggest that measuring the hemispherical transmittance of the soiling accumulated on a PV glass coupon can give enough information to quantify the impact of soiling on energy production. Each PV technology is found to have a preferred spectral region, or a specific single wavelength, for which the transmittance through a PV glass coupon could be used for the best estimation of soiling losses. Overall, considering the average spectral transmittance between the extreme wavelengths of the material-specific absorption band, or the transmittance of soiling at a single wavelength between 500 and 600 nm yields the best estimations for different PV technologies. The results of this work can lead to innovative approaches to detect soiling in the field and to estimate the impact of spectral changes induced by soiling on PV energy production. Image 1017542 • The transmittance of an outdoor-mounted PV glass coupon was monitored for a year. • Broadband or single-wavelength transmittance can predict the PV panel soiling ratio. • The best single-wavelength estimations are found between 500 and 600 nm. • The average transmittance over the PV material-specific band has a high correlation. • The average transmittance in the visible correlates better than the UV or NIR bands. [ABSTRACT FROM AUTHOR]

• We formulate maximum harvest area constraints considering hydrological connectivity. • We introduce the concept of the Effective Hydrological Neighborhood (EHN). • We develop an algorithm to compute the EHN for each grid cell in a forest stand. • We obtain the maximum number of cells that can be harvested in any horizon's period. • We determine the minimum number of years required to completely harvest each stand. Forest managers have struggled to develop several measures to mitigate the impacts of logging operations on soil erosion. Two measures have consisted in considering slope restrictions and limiting the size of clearcut harvest areas in timber harvest scheduling models by means of adjacency constraints. However, these constraints build on an externally predefined limit on harvest area valid to all stands regardless of their topographic features. Thus, we present a methodology to formulate maximum harvest area constraints for each stand on the basis of its topographic features and hydrological connectivity. Using a grid-based digital elevation model, we first introduce the concept of the "Effective Hydrological Neighborhood" and propose a method to compute it through the analyses of water flow directions and the LS topographic factor of the USLE. Then, we develop a recursive procedure to compute for each stand the maximum harvest area in any single period and in consecutive periods of the planning horizon. Finally, we formulate a set of maximum harvest area constraints for each stand. The methodology is applied to a eucalyptus plantation in northwestern Spain. The constraints can then be considered in strategic timber harvest scheduling models along with other constraints. In this way, the harvest plans derived at this planning level can be compatible with later solutions considering hydrological connectivity concerns at the tactical level. [ABSTRACT FROM AUTHOR]

• Mastication of burned trees did not significantly change soil physical properties. • Mastication of burned trees did not enhance post-fire soil losses. • Mastication residues in crown-fire affected areas did not help reduce soil erosion. • Mastication of non-commercial burned trees did not affect vegetation recovery. Forest mastication is frequently used as a fuel reduction treatment aimed at minimising severe wildfires in fire prone areas worldwide. In recent years, mastication of non-commercial burned trees has become common practice in NW Spain, as a way of providing cover on the burned soil and preventing erosion. However, little is known about the possible effects on soil conservation and vegetation recovery. In this study, 20 experimental plots were established in a Pinus sylvestris L. plantation affected by a crown fire that caused moderate-high soil burn severity in the summer of 2016. Immediately after the fire, burned trees were masticated in half of the plots, while burned trees were left standing in the other half of the plots during the first two years after the fire. The objectives of the study were to determine how mastication affected soil erosion, soil physical properties (soil penetration resistance, soil shear strength, soil bulk density) and vegetation recovery. The masticated material covered 43% of the burned soil. During the first year after wildfire + mastication, precipitation was lower than the annual mean level in the area, and the mean soil loss in the untreated burned soils (5.7 Mg ha−1) was not significantly different from that in the masticated plots (5.0 Mg ha−1). Mastication did not have any detrimental effects on either the soil physical properties analysed or on the regeneration of natural vegetation. The results indicated that in addition to mastication of severely burned non-commercial trees, extra mulch should be applied to reduce the risk of soil erosion. Mastication after wildfire is not detrimental to soil conservation. No advantage was obtained by leaving the standing burned trees on site, in relation to reducing soil erosion or enhancing vegetation recovery. [ABSTRACT FROM AUTHOR]

Context: In the Andalusia region (Spain), olive grove agro-systems cover a wide area, forming social-ecological landscapes. Recent socioeconomic changes have increased the vulnerability of these landscapes, resulting in the abandonment and intensification of farms. The provision of the main ecosystem services of these landscapes have thus been degraded. Objectives: To analyse the sustainability of an olive grove social-ecological landscape in Andalusia. Specifically, to develop a quantitative model proposing land planning and management scenarios, considering abandonment, production and economic benefits of olive crops in different conditions of erosion and management. Methods: We applied a dynamic model using agronomic and economic data, to evaluate different types of olive management. We considered different levels of erosion, the loss of production related to this erosion, and useful life spans for each type of management. We simulated scenarios for the long-term assessment of dynamics of crops, abandonment rate, production and benefits. Results: (a) There was a loss of productive lands and benefits in the medium term in the more intensive crops. (b) Scenarios that partially incorporated ecological management proved to be more sustainable without economic subsidies. (c) The spatial combination of integrated, intensive and ecological plots was sustainable, and was well balanced from an economic, productive and ecological point of view. Conclusions: Scenarios that partially incorporate ecological management allowed the best economic and environmental balance. However, to ensure the sustainability of olive landscapes, farmers should be financially rewarded for their role in the conservation of ecosystem services through landscape stewardship and direct environmental payments. [ABSTRACT FROM AUTHOR]

Abstract In the Mediterranean region, floods are expected to increase as a result of climate change and knowledge of soil erosion hot spots during exceptional rainfalls is required to support mitigation measures. This study quantifies the main sediment sources during an exceptional rainfall event in 2012 (235 mm) at the outlet of two catchments located in NE Spain. To this purpose, suspended sediments were collected during the flood event, complemented with entrapped sediments in mat taken one year after the event. We used fingerprinting methodology and applied the FingerPro unmixing model to estimate the contribution from main sources. The selected tracers clearly distinguished agricultural, rangeland, subsoil and channel banks as the four potential sources in both catchments. In the Vandunchil catchment, the 8 time-integrated suspended sediment samples revealed changes in source contribution during the 2-h sampling sequence. There were relatively high contributions from rangeland, agriculture and subsoil at the beginning of the sampling, representing 30, 40 and 35% of the total source contributions, respectively. Our records captured the delivery of pulses of eroded surface soil transported by runoff with direct connectivity to the stream. The sequence was followed by a sharp increase in channel bank contribution (up to 90%) in comparison to the other sources, reflecting streambank erosion and landslide occurrence, which manifested during the flood. In contrast, in the La Reina catchment, agricultural soils contributed the most (65%) and, together with subsoils (32%), were the main sources. These results reflect the effect of the higher connectivity and slope gradient of these cultivated fields of the La Reina catchment in comparison with those of the Vandunchil catchment. We discuss the possibility of using different properties, such as radionuclides, geochemistry and magnetic measurements, as tracers to distinguish between potential sources during an exceptional event in upland Mediterranean catchments. Our results support the use of fingerprinting techniques to determine variations in source contribution and sediment provenance during flood events, as extreme rainfalls are main drivers of sediment mobilization and key factors in changing landscapes. This is essential in identifying vulnerable hot spots, in which early-stage interventions are needed, and for helping policy makers with management of soil and water resources. Graphical abstract Image 1074 Highlights • Unique opportunity to capture soil response during an exceptional event of 235 mm. • Suspended sediment properties changed during the flood event. • Source contributions varied in response to the rainstorm in a short period. • Switch from soil sources to channel bank provenance was captured during the flood. • Land use and connectivity determined the suspended sediment provenance. [ABSTRACT FROM AUTHOR]

Soil erosion modeling in olive groves requires precise and accurate spatial data for the representation of topography associated with each time epoch considered. The precision and accuracy of altimetric values affect the quality of the digital elevation model (DEM) and therefore these requirements must be added to the necessity to generate high resolution DEMs. The increase of quality implies: 1. Improving the quality of the instrumentation and methodology applied in the field data collection and 2. Minimizing errors from the interpolation algorithm used to generate the digital terrain model. Currently, RTK networks are an indispensable complement to global navigation satellite systems (GNSS) precise positioning. The availability of highly accurate three-dimensional real time positioning has opened the door to new applications, making network-based real time kinematic (NRTK) positioning an attractive spatial data source for modeling soil erosion in small areas. This paper analyzes the quality of NRTK altimetric positioning supported by a local active network and its application in a test olive grove in SE Spain for soil erosion modeling. An evaluation procedure was implemented at several test sites distributed throughout an olive grove environment with special emphasis on filtering and checking the NRTK solutions in the vertical component. The precision in this component revealed a mean value of 15 mm and the vertical accuracy reached maximum values of 30 mm. In order to generate high resolution and accuracy DEM from the NRTK data, cross sections on the test olive grove were surveyed. The average altimetric quality value (CQ1D) of points surveyed was 0.017 m, according to the standard deviation estimated at test points. Based on the quality results, NRTK positioning is an accurate and reliable methodology for monitoring the erosion processes of small areas in an olive grove environment. [ABSTRACT FROM AUTHOR]

Abstract Dissolved solids (DS) and suspended sediment (SS) loads are considered relevant environmental problems. They are related to a wide range of on-site and off-site impacts, such as soil erosion or salinization of water bodies. In this study, the dynamics of DS and SS concentrations and loads were assessed in five small watersheds covering representative agricultural land uses in Navarre (Spain). To this end, discharge, DS and SS concentration data were collected during ten hydrological years at each watershed outlet, and loads were computed from discharge and concentration values. DS concentration followed a seasonal pattern imposed by the availability of water, with higher concentrations recorded in low-flow periods and lower concentration in the high-flow period. SS concentration was extremely variable, with a range of 2–4 orders of magnitude in concentration for any specific discharge. Temporal variations (both intra- and inter-annual) in DS loads were explained by differences in runoff, whereas those of SS were not, being the SS loads associated mainly with specific high flow events. These temporal patterns were observed for both agricultural (this study) and non-agricultural (literature) watersheds. From the data in the Navarrese watersheds and those available in the literature, we inferred that agricultural land use, in general, tends to increase the concentration of both DS and SS. Regarding DS and SS yields, the effects of agricultural land use on DS yields are controlled by the changes in runoff rather than the (small) changes in DS concentration. In this sense, land uses changes expected to increase runoff (i.e., a shift from forested to arable or from rainfed to irrigated agriculture) would increase DS yields. On the other hand, agricultural land use tends to increase SS yields, although the effect is highly variable depending on site-specific factors, both natural (e.g., watershed shape) and anthropogenic (e.g., degree of soil conservation practices). In the Navarrese watersheds, DS yields ranged from 1.1 to 2.2 Mg ha−1 year−1 whereas SS yields ranged from 0.3 to 4.3 Mg ha−1 year−1. DS yields seem to dominate under non-agricultural conditions and in most agricultural land uses at the small watershed scale. On the other hand, SS yields dominate in watersheds with increased soil erosion as a consequence of arable land use over erosion-prone watersheds. Highlights • Dissolved solids concentration follows a seasonal pattern. • Suspended sediment concentration was extremely variable. • Dissolved loads behave conservatively with water. • The dissolved load dominated the exportation in most of the cases. • Agricultural land use increases suspended sediment concentration and loads. [ABSTRACT FROM AUTHOR]

Applying mulch to severely burned soils is common practice in fire-prone areas such as the NW Spain. Mulch that provides >80% cover can reduce post-fire soil erosion by up to 90%; however, this level of cover can sometimes be difficult to achieve in remote areas due to the logistic constraints. Although application of mulch strips is a possible alternative approach, there is no information available about the effectiveness of this technique. Such information is critical in protected areas where mulch application can modify the recovery of natural vegetation by altering the soil moisture regime. In this study, the effects of the application of 20 m wide straw mulch strips on soil erosion, soil moisture and vegetation recovery were assessed during the first year after a high-severity fire that occurred in September 2020 in two European dry-heathland areas. During the first year after the fire, the mean sediment yields in the untreated plots were 18.5 Mg ha−1 and 33.8 Mg ha−1, respectively at the Lobios and Vilariño study sites. Although the straw mulch strips reduced soil erosion by >70% on average, erosion rates remained high at both sites. Soil moisture contents in mulch-treated areas were significantly higher than in untreated areas during spring and summer. Mulching affected vegetation recovery in different ways, i.e., it had neutral to positive effects, depending on the study site. No alteration in species composition was observed in either of the sites as a result of treatment application. In summary, the reduction in soil erosion after the application of straw mulch strips covering 67% of burned soil under the conditions of the present study under the conditions of the present study reduced a 70–75% of soil erosion after a high-severity wildfire. • Straw mulch strips significantly reduced (70–75%) post-fire soil erosion. • Mulch application increases soil moisture relatively to the control in spring-summer. • The effects of mulch on vegetation cover ranged from neutral to positive. • Mulching did not affect plant species richness. [ABSTRACT FROM AUTHOR]

To ensure sustainable agricultural management, there is a need not only to quantify soil erosion rates but also to obtain information on the status of soil water content and soil loss under different soil types and land uses. A clear understanding of the temporal dynamics and the soil moisture spatial variability (SMSV) will help to control soil degradation by hydrological processes. This study represents the first attempt connecting cosmic-ray neutron sensors (CRNS) with soil erosion research, a novel approach to explore the complex relationships between soil water content (SWC) and soil redistribution processes using two of the most powerful nuclear techniques, CRNS and fallout 137Cs. Our preliminary results indicate that CRNS captured soil moisture dynamics along the study toposequence and demonstrated the sensitivity of neutron sensors to investigate the effect of parent material on soil water content. The Empirical Orthogonal Function (EOF) analysis of the comprehensive data from seven CRNS surveys revealed that one dominant spatial structure (EOF1) explains 89.2% of SMSV. The soil redistribution rates estimated with 137Cs at the nine locations along the hillslope, together with local factors related to soil properties (SOC, soil depth, hydraulic conductivity) and land use showed significant correlations with EOF. This study provides strong field evidence that soil type significantly affect SMSV, highlighting the key impact on soil erosion and sedimentation rates. Nevertheless, more research is needed to investigate the specific contributions of soil properties to the spatial variability of soil moisture and their subsequent effects on soil redistribution dynamics of interest for soil management. [Display omitted] • Combining nuclear techniques for exploring soil moisture and soil redistribution. • Parent material controls soil moisture spatial variability (SMSV). • Seven CRNS surveys at nine locations captured 85.5% of SMSV using EOF analysis. • Soil depth, hydraulic conductivity, erosion rates and SOC significantly affect SVSM. • CRNS and 137Cs provide insights into the link between SWC and soil redistribution. [ABSTRACT FROM AUTHOR]

Soil erosion is a very serious environmental problem worldwide, with agriculture considered the main source of sediment in inland waters. In order to determine the extent and importance of soil erosion in the Spanish region of Navarra, in 1995 the Government of Navarra established the Network of Experimental Agricultural Watersheds (NEAWGN), which consists of five small watersheds representative of local conditions. In each watershed, key hydrometeorological variables, including turbidity, were recorded every 10 min, and daily samples were taken to determine suspended sediment concentration. In 2006, the frequency of suspended sediment sampling was increased during hydrologically relevant events. The main objective of this study is to explore the possibility of obtaining long and accurate time series of suspended sediment concentration in the NEAWGN. To this end, simple linear regressions between sediment concentration and turbidity are proposed. In addition, supervised learning models incorporating a larger number of predictive variables are used for the same purpose. A series of indicators are proposed to objectively characterize the intensity and timing of sampling. It was not possible to obtain a satisfactory model for estimating the concentration of suspended sediment. This would be mainly due to the large temporal variability found of the physical and mineralogical characteristics of the sediment, which would be affecting the turbidity value, independently of the sediment concentration, per se. This fact would be particularly important in small river watersheds such as those of this study, and especially if their physical conditions are spatially and temporally radically disturbed by agricultural tillage and by a constant modification of the vegetation cover, as is the case in cereal basins. Our findings suggest that better results could be obtained by including in the analysis variables such as soil texture and exported sediment texture, rainfall erosivity, and the state of vegetation cover and riparian vegetation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Wildfire has historically been an alteration factor in Mediterranean basins. Despite Mediterranean ecosystems' high resilience, wildfire accelerates erosion and degradation processes, and also affects soil functionality by affecting nutrient cycles and soil structure. In semi-arid Mediterranean basins, check dams are usually built in gullies and channels after fire as a measure against soil erosion. Although check dams have proven efficient action to reduce erosion rates, studies about how they affect soil functionality are lacking. Our approach focuses on how soil functionality, defined as a combination of physico-chemical and biological indicators, is locally affected by check dam construction and the evolution of this effect over time. Soils were sampled in eight check dams in two semi-arid areas at SE Spain, which were affected by wildfire in 2012 and 2016. The study findings reveal that by altering sediments cycle and transport, check dams influence soil's main physico-chemical and biochemical characteristics. Significant differences were found between check dam-affected zones and the control ones for many indicators such as organic matter content, electrical conductivity or enzymatic activity. According to the ANOVA results, interaction between check dams influence and time after fire, was a crucial factor. PCA results clearly showed check-dams influence on soil functionality. [ABSTRACT FROM AUTHOR]

Gully erosion in agrosilvopastoral systems of SW Spain represents a common degradation process, but has been hardly analysed. The suitability of using the Unmanned Aerial Vehicles (UAV) and Structure from Motion photogrammetry (SfM) workflow to map small valley-bottom gullies in these landscapes was tested. The results showed centimetre-level accuracy. Observed strengths and limitations of the UAV+SfM workflow in the study areas are discussed. The resulting cartography allowed mapping soil erosion forms at outstanding spatial scales. All study areas showed evidences of degradation. [ABSTRACT FROM AUTHOR]

Severe fire greatly increases soil erosion rates and overland-flow in forest land. Soil erosion prediction models are essential for estimating fire impacts and planning post-fire emergency responses. We evaluated the performance of a) the Revised Universal Soil Loss Equation (RUSLE), modified by inclusion of an alternative equation for the soil erodibility factor, and b) the Disturbed WEPP model, by comparing the soil loss predicted by the models and the soil loss measured in the first year after wildfire in 44 experimental field plots in NW Spain. The Disturbed WEPP has not previously been validated with field data for use in NW Spain; validation studies are also very scarce in other areas. We found that both models underestimated the erosion rates. The accuracy of the RUSLE model was low, even after inclusion of a modified soil erodibility factor accounting for high contents of soil organic matter. We conclude that neither model is suitable for predicting soil erosion in the first year after fire in NW Spain and suggest that soil burn severity should be given greater weighting in post-fire soil erosion modelling. [ABSTRACT FROM AUTHOR]

The exposure of tree or shrub roots represents a clear indicator of soil loss in the surrounding area. Previous studies have used this type of botanical evidence to estimate soil erosion rates, preferring roots at some distance from the tree stem because the inflection point (or root collar) undergoes a vertical displacement caused by basal growth. The aim of this paper is to develop a method that combines the inflection point of holm oaks and high-resolution digital images obtained by means of a terrestrial laser scanner to estimate soil erosion rates in Mediterranean dehesas. To correct for vertical displacement, the basal growth of each tree was determined in the field, differentiating the part of the roots that had been exposed by erosion from that generated by wood growth. Two datasets obtained through different approaches were used for validating the basal growth measured in the field survey: (i) a growth study analysing stems and cores of holm oaks and (ii) field measurements of basal growth of holm oaks located in an area without soil erosion. The results obtained by each method offered similar mean values (12.7 and 8.4 cm, respectively) as compared to the values estimated in the field survey (10.2 cm). Afterwards, soil erosion rates were corrected, reducing the values on average by 40%, with a mean loss of 26.7 t ha ‐1  y −1 . No relationship was found between tree age and basal growth. On the other hand, soil erosion rates showed a slightly negative trend with relation to tree age, indicating an upward tendency of soil losses from the year 1640 to 2014. Finally, it was possible to define three periods with varying erosion rates: 10.4 t ha −1  y −1 (1640–1830), 19.2 t ha −1  y −1 (1831–1888) and 27.2 t ha −1  y −1 (1889–2014). [ABSTRACT FROM AUTHOR]