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Soil water erosion on cultivated lands represents a severe threat to soil resources in the world, and especially in Mediterranean areas, due to their topographic, edaphic and climatic conditions. Among the cultivated lands, vineyards deserve a particular attention because, aside representing one of the most important crops in terms of income and employment, they also have proven to be the form of agricultural use that causes one of the highest soil losses. Although the topic of soil water erosion on vineyards has been studied, it still raises uncertainties, due to the high variability of procedures for data acquisition, which consists into different scales of analysis and measurement methods. There is still a great gap in knowledge about the effect of triggering factors on soil water erosion and, so far, an effort to quantify this effect on the Mediterranean viticulture has not been made yet. Therefore, this paper review aims to (i) develop a documented database on splash, sheet and rill erosion rates in Mediterranean vineyards, (ii) identify and, if possible, quantify the effect of triggering factors such as topography, soil properties, rainfall characteristics and soil conservation techniques on soil water erosion, and (iii) provide suggestions for a more sustainable viticulture. Although the large variability of data, some general trends between erosion rates and triggering factors could be found, as long as data were categorized according to the same measurement method. However, no general rule upon which to consider one triggering factor always predominant over the others came out. This paper review supports the importance of monitoring soil water erosion by field measurements to better understand the relationship between the factors. However, protocols should be established for standardizing the procedure of collecting data and reporting results to enable data comparison among different study areas. [ABSTRACT FROM AUTHOR]

Agricultural expansion in the Mediterranean resulted in plant and soil degradation due to the intensive use, climate conditions, and rugged terrain. After abandonment, the recovery of vegetation contributed to improvement in soil quality from a hydrological, pedological and geomorphological point of view. This paper shows three examples of ecosystem evolution in abandoned fields in Valencia, Murcia and Andalucia and the application of different methodological approaches that resulted in similar findings. In Valencia, the main responses were the recovery of vegetation after land abandonment and an increase in organic matter and infiltration capacity of soils. In Murcia, with the exception of some terraced areas on marls, where erosion processes following abandonment were important, land abandonment resulted in vegetation recovery, improved soil properties, and reduced surface wash and soil losses. In Andalucia, research along climatological gradients showed the relationship between vegetation patterns and soil moisture and the control that climate exerts on hydrological and erosive behaviour. The experimental research conducted in three different regions in Western Mediterranean demonstrated that abandonment can result in recovery of the geo-ecosystem as vegetation and soil quality improvements were shown. The marls areas in Murcia were the exception with low soil quality and low vegetation cover, and as a consequence showed evidence of high erosion rates after abandonment. [ABSTRACT FROM AUTHOR]

Mediterranean fluvial hydrology is characterised by decadal-to-multi-centennial length wet and dry episodes with abrupt transitions related to changes in atmospheric circulation. Since the mid-1990s site-based flood chronologies from slackwater deposits in bedrock rivers and regionally aggregated flood histories from alluvial deposits have developed increasingly higher resolution chronological frameworks, although regional coverage is still uneven. This paper analyses the spatial and temporal distribution of extreme Holocene hydrological events recorded in fluvial stratigraphy in the Iberian Peninsula (Spain and Portugal), southern France, southern Italy, Northern Africa (Morocco and Tunisia) and eastern Mediterranean (Greece, Crete, Turkey, Cyprus and Israel). This study constitutes the most comprehensive investigation of Holocene river flooding ever undertaken in the Mediterranean and is based on the analysis of 515 14 C and 53 OSL dates. It reveals that flood periods in different regions cluster into distinct time intervals, although region-wide flooding episodes can be identified at 7400–7150, 4800–4600, 4100–3700, 3300–3200, 2850–2750, 2300–2100, 1700–1600, 1500–1400, 950–800, ca. 300, 200–100 cal. BP. Periods with more frequent floods in the western Iberian region coincide with transitions to cool and wetter conditions and persistent negative NAO mode. In Northern Africa increased flood frequency coincides with periods of generally drier climate, while in the eastern Mediterranean there is a higher incidence of extreme flood events under wetter conditions. Our meta-data analysis identifies an out-of-phase pattern of extreme events across the Mediterranean over multi-centennial timescales, which is particularly evident between the western Iberian and eastern Mediterranean regions. This centennial-to-multi-centennial see-saw pattern in flooding indicates that bipolar hydroclimatic conditions existed in the Mediterranean during the Holocene. [ABSTRACT FROM AUTHOR]

Abstract: Understanding soil dynamics is essential for making appropriate land management decisions, as soils can affect the carbon content from the atmosphere, emitting large quantities of CO2 or storing carbon. This property is essential for climate change mitigation strategies as agriculture and forestry soil management can affect the carbon cycle. The Mediterranean dehesa (Mediterranean grassland ecosystem with scattered oak trees — grazing system with Quercus ilex spp. ballota) is a silvopastoral system that integrates forestry, agricultural and livestock practices. The dehesa is characterized by the preservation of forest oaks that provide environmental services including carbon capture and storage. This paper shows the relationships between soil properties and soil organic carbon (SOC) in two soil types: Cambisols (CM) and Leptosols (LP), with two management systems: organic farming (OF) for 20years and conventional tillage (CT) in a Mediterranean dehesa of southern Spain without cropping. An analysis of 85 soil profiles was performed in 2009 in Los Pedroches Valley (Cordoba, southern Spain). The SOC stock (SOC-S) was greater in CM (75.64Mgha−1) than in LP (44.01Mgha−1). Physical parameters were the main variables affecting soil development. SOC-S was very similar in OF and CT (CM [74.90Mgha−1-CT; 76.39Mgha−1-OF] and LP [44.77Mgha−1-CT; 43.25Mgha−1-OF]). Data analysis showed that management practices had little effect on SOC storage in the study zone. Significant differences between soil types and management practices were found in SOC content for different horizons. The stratification ratio was >2 in both soils types (CM and LP) and management systems (OF and CT). These results indicate that the soil is of high quality, and that management practices have little influence on SOC-S in Los Pedroches Valley. [Copyright &y& Elsevier]

Abstract: Water repellency (WR) is a common soil property in many fire-affected ecosystems, but it also occurs in long-unburned terrain. It can vary in space at different scales (between point and pedon or slope and catchment) and time (during the same day, between seasons or years, or with a post-fire recovery period). This paper: i) reports on the occurrence and persistence of WR in fire-affected calcareous forest soils under Mediterranean climatic conditions, examining its spatial variability at macro-, meso- and micro-scales, and monthly changes with soil moisture content; and ii) develops exploratory models to estimate the probability of the natural background (not fire-induced) WR to occur through a Mixed-Effect Logistic Regression Model. Four sites with comparable soil and vegetation types were studied, all of them burned in 1979, the third again 1999, and the fourth in April 2008. All sites were sampled immediately after the fire of 2008, a further 17 times until July 2009, and once more in August 2011. At each site, 5 random plots (10cm×10cm) were selected for each of the vegetation types: Pinus halepensis, Quercus coccifera, Rosmarinus officinalis and bare soil. In each plot we carried out 10 Water Drop Penetration Time measurements at the surface and at 1cm depth. WR was detected in samples from all sites, although WR was most frequent at the soil surface at the sites last burnt in 1979. The recently burned site had similar WR to the long-unburned ones in surface but greater at 1cm depth, although for both depths WR was reduced by the following year. WR was still very low in the site burned 10years before. Variability of WR between different vegetation types was as high as within the same type at the same site, and similarly high at within sites (1ha) and at 10cm×10cm plot-scales. The lowest variability was found in bare soil plots because they were mostly wettable. An exploratory model to estimate the probability of WR occurrence was derived for each unburned site. The most powerful explanatory variables for the probability of WR to occur (P<0.0001) for both unburned sites were the covariate moisture content together with the category soil surface (associated to the fixed factor soil depth) for one site and P. halepensis (associated to vegetation type) for the other. The model input parameters are straightforward to obtain and the model may be a useful tool in estimating occurrence and fluctuation of soil WR. [Copyright &y& Elsevier]

Abstract: Variations in the distribution pattern of soil water repellency (SWR) and soil moisture are of major importance for the hydrological and geomorphological processes in Mediterranean burned areas, and also for their ecological implications concerning to re-establishment of the vegetation cover. This paper studies the influence of Rosmarinus officinalis L. and Quercus coccifera L. vegetated patches on SWR and their relationships with soil moisture content (SMC) and soil organic matter (SOM) in burned and unburned calcareous soils of a Mediterranean shrubland ecosystem, considering the first rainfall event occurred after the wildfire in Les Useres (Castellón, eastern Spain). In a burnt SSE facing hillslope (739605 West, 4449022 North), 8 microsites were selected under Q. coccifera and 20 under R. officinalis. Three concentric zones were distinguished around the plants: Zone I (stump), Zone II (intermediate) and Zone III (bare soil), showing differences on its soil surface appearance, which were considered for soil sampling and for field moisture measurements. In the nearest unburned zone, at the same hillslope, 8 microsites for each of the same species were also selected, on the basis that they were representative of the pre-fire conditions. The obtained results imply that fire caused a significant increase in SWR at R. officinalis stumps (measured by means of the water drop penetration time test, WDPT). However, at burned Q. coccifera microsites, SWR was destroyed by fire, at least in the 2mm soil fraction (WDPT<5s). Results also showed the presence of a gradient from the highest WDPT and SOM at Zone I to the lowest at Zone III for the two studied species, in that way that bare soil was wettable at burned and unburned microsites and this fact is also reflected on the spatial distribution of SMC. Field SMC showed an increasing gradient from the stumps towards the outer zone, and the differences between SMC in the stumps and bare soil were greater from burned than unburned microsites. Field SMC showed significant and negative correlation coefficients with the WDPT and SOM content for the two studied species. Moreover, a positive relationship between WDPT and SOM was found. Partial correlation analysis at burned microsites revealed that SMC and WDPT are influenced by the SOM. The hydrological and ecological implications of these results are discussed. [Copyright &y& Elsevier]

Abstract: The demographic pressure decrease in Southern Spanish Mediterranean mountainous areas in the mid twentieth century led to the abandonment of agriculture and rupture in the geo-ecosystem balance which had existed until then. Since then, different phases of recovery have been put into action to return the landscape to its earlier natural condition according to climate and soil degradation state after the abandon. In Mediterranean climatic conditions (between subhumid and semi-arid regimes), degraded soil recovery has followed different tendencies rendering the landscape in heterogenic and complex one. This heterogeneity has manifested in the vegetation pattern of abandoned fields. In this paper, we analyze the state of three abandoned fields situated under different Mediterranean climatic conditions from the recovery point of view by means of monitoring the effects of spatial and temporal variability of soil moisture in the vegetation pattern over a period of two years sampling (Nov. 2002–Nov. 2004). The results showed that: i) more annual rainfall volume did not guarantee success in the biological recovery of the system due to the influence of other factors such as the degradation state of the soil post-abandonment or the steep slope gradient; ii) soil moisture variability tended to play a more important role in affecting vegetal cover in semi-arid conditions; and iii) in dry climatic conditions the system demonstrated greater signs of recovery (greater biodiversity). [Copyright &y& Elsevier]

Abstract: Sediment transport in the Ribera Salada stream was estimated from continuous suspended and bedload monitoring between 2005 and 2008. The Ribera Salada basin is a mountainous perennial river in the Southern Pyrenees and is representative of the extensive forestry land use in this upland region. Water and sediment fluxes have been analysed with the aim of determining the thresholds, duration, ranges and relative contributions of the two sediment transport modes (suspended and bedload), and their variability in relation to the basin''s annual hydrology. The stream''s hydrology in the first two sampling years was average in the context of a 10-yr series of the basin, while 2007–2008 can be classified as a wet year. The specific total sediment load during the study period amounted to 12tkm− 2y− 1, a low value compared with similar Mediterranean counterparts. The maximum load (31.5tkm− 2y− 1) was observed during the wettest year of the monitoring programme. During average years most of the total load (>90%) was transported in suspension; consequently, suspended sediment transport is more frequent through time. In contrast, bedload occurs sporadically during floods that exceed certain hydraulic thresholds, corresponding to a flow equalled or exceeded 4% of the time, that yields an average shear stress of ∼35Nm− 2. Under such conditions bedload transport becomes relevant and, if the threshold is frequently exceeded as in relatively wet years such as 2007–2008, may constitute the majority of the total sediment load (74%). This paper provides new evidence of the distinct role of sediment transport modes in stable fluvial environments where only sporadic inputs of surplus energy (flow discharge) determine the dominant mode, magnitude and duration of their respective contribution. [Copyright &y& Elsevier]

Abstract: Traditional rainfed agriculture in semi-arid regions heavily relies on soil and water conservation (SWC) structures to supplement the sparse rainfall. As referring to the ecosystem functions of these constructions, when extensive such systems prevent any runoff into the fluvial system. The extent to which these dams and terraces resist major events is variable, and earthen dams can be major sediment sources. Extensification and increasing mechanization of rainfed agriculture in marginal areas have led to a change in cropping systems. Large-scale almond and olive plantations with widely spaced trees do not rely on runoff water, but draw the soil water from a large soil volume of bare soil maintained by regular shallow tillage. The high density of terraces has now become a nuisance to the farmers. The aim of this paper is to i) demonstrate the degradation of SWC structures and the relative importance of the driving forces, ii) assess the limits of the protection that earthen dams can provide by surveying their resistance during a heavy storm (return period 8.2 years) and iii) demonstrate the implications of the abandonment of SWC structures over the period 1956–2005 for the hydrological connectivity between croplands and the ephemeral rivers system. The headwaters of a marl catchment with a continuous area treated with SWC structures in Murcia region (Spain) already had a very high density of step terraces and check dams (182 m ha−1) in 1956. This density decreased by 27% in the period 1956–2005. Furthermore, many terraces have not been maintained and flow traces indicate that they no longer retain water. This is particularly true for the check dams in abandoned lands. The distance between the step terraces has increased over time, making them vulnerable to erosion. The mean drainage area of the dams that failed during the heavy storm was significantly (3.16 ha) higher than that of the ones that remained intact (1.11 ha). The probability of failure increases with drainage area from P =0.16 for an area of 1.8 ha to P =0.8 for an area of 20 ha. The percentage of cropland draining directly on the river system without interference of a check dam has increased from just 9% in 1956 to 31% in 2005 and 40% after the storm in November 2006. [Copyright &y& Elsevier]

Abstract: Runoff and soil loss from forest road backslopes is a serious problem in Mediterranean areas. Surface runoff and sediment production on backslopes of forest roads in Los Alcornocales Natural Park (southern Spain) has been studied in this paper using a simple portable rainfall simulator at an intensity of 90 mm h−1. One hundred rainfall simulations were performed on bare and vegetated road backslopes during summer and winter in order to study seasonal differences. Runoff coefficients and soil loss rates were lower on the vegetated plots than on the bare ones. Runoff coefficients increased 1.7 (bare backslopes) and 3.1 times (vegetated backslopes) from summer to winter. Preserving the vegetation cover over 20% is recommended for keeping soil loss rates under low levels, especially during winter. [Copyright &y& Elsevier]