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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]

Semiarid and arid environments are frequently structured in vegetation patches that heterogeneously distribute water resources (water runoff and soil moisture). This redistribution is interrelated with episodes of rainfall triggering pulses of plant growth according to the Trigger–Transfer–Reserve–Pulse (TTRP) model. Spatial heterogeneity in the hydrological behaviour of surface patches has been described in Mediterranean mining restored hillslopes. Nevertheless studies describing the interactions of this hydrological heterogeneity with ecological processes on restored environments are lacking. This study investigates the relationships between overland flow running at hillslope scale and ecosystem processes at patch scale in restored hillslopes. We selected three approximately 20 year old restored hillslopes along a gradient of overland flow (hillslope runoff coefficients are 15.9%, 2.2% and 0.3% for the three experimental hillslopes). We studied environmental conditions describing the ecohydrological interactions under the TTRP approach for arid and semiarid environments. Our results indicate that in restored hillslopes: 1) soil moisture content was associated to the type of vegetation patches; 2) higher soil water content enhanced vegetation diversity and soil properties, improving vegetation performance and colonization opportunities; and 3) there was an inverse relationship between the volume of overland flow and soil moisture at the hillslope scale, influencing, in turn, ecohydrological processes at the patch scale. Overall our results highlight the importance of overland flow modifying soil moisture distribution at patch scale and hence, influencing vegetation dynamics and ecological succession in these novel ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: This study reports the soil–plant relationships within a protected landscape in semiarid SE Spain that includes salt marshes and temporary streams and that is affected by agricultural water leaching. The main objective was to establish a conceptual model in order to use vegetation as bioindicator of soil conditions. With this model, environmental changes – based on the observation of vegetation – could be detectable, allowing the prevention of environmental impacts and the improvement of the environmental management of the studied area. Eight sampling stations with a total of 39 plots were established for the sampling of vegetation (floristic composition and species abundance) and soil (moisture, pH, redox potential, electrical conductivity and soluble ions). Multivariate analysis showed that vegetation was closely related to soil moisture and salinity. The soils colonised by steppe grasses (dominated by Lygeum spartum) and halophilus and halonitrophilus shrubs (dominated by Suaeda vera and Limonium spp.) were the driest (moisture <~20%) and least saline (EC <~30dSm−1). Phragmites australis, Sarcocornia fruticosa and Arthrocnemum macrostachyum dominated in the most saline and wettest soils. P. australis reached maximum cover at EC values ~40dS m−1 and soil moisture ~30% and consistently appeared on those soils with lower seasonal contrasts of moisture and salinity. Between 30 and 80dSm−1 of soil salinity, S. fruticosa reached maximum cover (~100%) while A. macrostachyum did not exceed ~80%. Outside this range of salinity S. fruticosa declined (cover <10%), while the other species maintained cover >~40%. In addition, A. macrostachyum grew in soils with stronger seasonal changes of moisture and salinity. Based on the model established, if an expansion of P. australis is detected, an increase in soil moisture and a decrease in soil salinity during the year could be inferred. These changes could be due to an increased entry of effluents of fresh and/or brackish water from agricultural areas. In turn, an increase in the cover of A. macrostachyum would indicate higher soil salinity, which could be a consequence of an increase in the evaporation rates (due to rising temperatures) and a decrease in rainfall (predicted consequences of global warming). The expansion of S. fruticosa would be favoured under relatively high soil salinity conditions (which limit P. australis expansion) jointly with high soil moisture, without strong seasonal changes (which limit A. macrostachyum expansion). Our results support the role of vegetation as bioindicator of disturbances and the use of soil–plant relationships models to improve the environmental management of saline ecosystems. [Copyright &y& Elsevier]

Abstract: This study evaluates the spatial and temporal variability in soil water repellency (SWR) in two Mediterranean rangelands (with similar tree and shrub species) and its relationships to different eco-geomorphologic variables (climate, aspect, soil cover and some soil properties). Every month from October 2008 to May 2009 (rainy season), soil moisture and SWR was measured in field conditions by means of gravimetric method and Water Drop Penetration Test, respectively. Also, disturbed and undisturbed soil samples were taken to analyze some soil properties: bulk density, texture, organic matter, pH and electrical conductivity. The entire tests were performed in north and south aspect hillslopes and beneath shrub and bare soil in every of them. The results indicated that: i) climatic conditions seem to be more transcendent than the vegetal species for explaining the variability in SWR; ii) thus, SWR appears to be controlled by the antecedent rainfall and soil moisture; iii) more severe SWR were observed in patches characterized by sandier soils and/or higher organic matter contents; and iv) the factor ‘hillslope aspect’ was not found so crucial as it was expected. [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: Soil moisture is considered the main limiting factor governing the structure and dynamics of vegetation in drylands. Soil erosion is perceived as a critical process affecting these systems, especially when rill formation occurs, as rill networks can condition the availability and spatial distribution of soil moisture. To assess the impact of soil erosion processes on the dynamics of Mediterranean-dry reclaimed systems, during the 2005–06 hydrological year we monitored the soil moisture regime (temporal availability and spatial distribution) and the associated responses describing vegetation performance (plant water status and potential seed germination) and vegetation structure in five coal-mining reclaimed slopes subjected to different rill erosion rates (from 0 to about 70tha−1 year−1). Rill network development leads to increased runoff connectivity and to concentration of water flow along the channeling network. As a result, water loss from the slope system is maximized. Simultaneously, the spatial distribution of soil moisture is ruled by the pattern of geomorphic forms (rill and interrill units). The ecological consequences are led by the intensification of water stress and the occurrence of unfavorable conditions for plant recruitment and natural colonization, causing a non-linear decline of species richness and aboveground biomass at the slope scale level. When dense rill networks are developed, long-term effects of erosion result in a sharp ecosystem transition to a very simple and low productive plant community spatially organized in downward spots adjacent to the rills, where plants minimize simultaneously water stress and the mechanical disturbance associated to concentrated flows. [ABSTRACT FROM AUTHOR]