Mediterranean Agrosystems Research Articles

Monitoring data on the effect of domestic livestock and rabbits on Androcymbiumeuropaeum (Lange) K. Richt. and its xerophytiques pastures for thirteen years.

Dataset of annual monitoring of herbivory effects on the conservation status of the endangered species Androcymbiumeuropaeum (Lange) K. Richt and its associated plant communities is presented in this manuscript. This dataset encompasses the annual monitoring of herbivory effects on the conservation status of the endangered species Androcymbiumeuropaeum. Since 2010, the SERPAM Department (Service of Evaluation, Restoration and Protection of Mediterranean Agrosystems) at the Zaidin Experimental Station, belonging to the Spanish National Research Council (CSIC-EEZ), has conducted annual sampling to assess the impact of both domestic and wild livestock, specifically rabbits, on the pastures where A.europaeum lives. The study consisted of a randomised block design, implementing three distinct treatments to evaluate different management strategies: (1) rabbit and domestic herbivory, (2) exclusion of domestic livestock and (3) exclusion of rabbits and domestic livestock. Within each treatment, two types of monitoring were conducted. Firstly, the abundance of A.europaeum was estimated by counting individuals within 50 cm x 50 cm quadrats. Secondly, plant species diversity was assessed along 2-m long transects using the modified Point-Quadrat method. The research was conducted within the Cabo de Gata-Níjar Natural Park in southern Spain, specifically in the Amoladeras Nature Reserve in Almería. The dataset contains information spanning from 2010 to 2023, providing valuable insights into the annual monitoring of herbivory effects on the conservation status of A.europaeum, contributing to our understanding of the species' interaction with domestic and wild animal in the studied area.

Open areas associated with traditional agriculture promote functional connectivity among amphibian demes in Mediterranean agrosystems

ContextFunctional connectivity across fragmented habitat patches is essential for the conservation of animal populations in humanized landscapes. Given their low dispersal capacity, amphibians in the Mediterranean region are threatened by habitat fragmentation and loss due to changes in land use, including agricultural intensification.ObjectivesWe assessed patterns of functional connectivity of a Near Threatened Mediterranean amphibian, the sharp ribbed newt (Pleurodeles waltl), in an agricultural landscape matrix in NW Spain subject to different intensification regimes.MethodsWe sampled newts in 17 ponds embedded in a terrestrial habitat matrix dominated by agricultural land uses. Genome-wide molecular markers (1390 SNPs) were used to assess patterns of genetic diversity and gene flow among ponds. We tested the role of landscape features on functional connectivity using isolation by resistance models incorporating information on Normalized Difference Vegetation Index (NDVI) data.ResultsWe found low levels of genetic diversity in all sampled populations. Global FST estimates and cluster analyses revealed shallow but significant genetic structure in the study area, with NDVI-based resistance models showing that open areas (rainfed crops and grasslands) offer lower resistance to gene flow and thus promote functional connectivity among demes.ConclusionsOur study highlights the important role of landscape features, such as open areas resulting from traditional rainfed agriculture, in promoting functional connectivity between amphibian populations in Mediterranean agrosystems. Conservation policies must adopt a functional network strategy and protect groups of inter-connected temporary ponds across the traditional agricultural matrix to efficiently preserve their associated biotic communities.

Effect of implementation of irrigation on raptor and corvid populations in a Mediterranean agrosystem

We analyzed changes in the composition of the community of birds of prey and corvids in a rainfed agrosystem after the transformation of 37.2 % of the sampled area into irrigated land between 2005 and 2020. We sampled 57 transects (372 km per year) and fitted generalized linear mixed models (GLMM) to study changes in species occurrence. Our results showed that specific richness and the Shannon index did not vary significantly between rainfed and irrigated transects, but there was a certain positive trend when comparing the years 2005 and 2020. Regarding the differences detected for each species, the occurrence of Montagu’s harrier Circus pygargus, hen harrier Circus cyaneus, Eurasian short-toed eagle Circaetus gallicus, griffon vulture Gyps fulvus and carrion crow Corvus corone was significantly lower in irrigated land than in rainfed land, while magpie Pica pica, Western marsh harrier Circus aeruginosus, common kestrel Falco tinnunculus and black kite Milvus migrans showed a significantly higher occurrence in the irrigated transects. In addition, our findings confirm a significant decrease in occurrence between 2005 and 2020 both in rainfed and irrigated areas for Montagu’s harrier, hen harrier and magpie, while Western marsh harrier, golden eagle Aquila chrysaetos, common buzzard Buteo buteo, red kite Milvus milvus, griffon vulture Gyps fulvus, red-billed chough Pyrrhocorax pyrrhocorax and Western jackdaw Coloeus monedula were detected significantly more frequently in 2020 than in 2005. These results suggest that assessment of the impact of a new irrigation system should focus on the most characteristic species of rainfed agrosystems because the apparently positive effect on other species, equally protected but more generalist, may mask the real effect on conservation.

Long-Term Field Evaluation of Conventional vs. Micropropagated Plants of Chrysanthemum cinerariifolium

Pyrethrum is a perennial herbaceous plant endemic to the eastern coast of the Adriatic Sea, and introduced in large areas of nearly all continents, where it is cultivated for the industrial extraction of pyrethrins. Pyrethrins are a group of six closely related monoterpene esters, widely used as natural insecticides. The world production of natural pyrethrins is lower than the market demand, and a wider introduction of this crop within the Mediterranean agrosystems could be an appealing opportunity for farmers and manufacturers. The availability of adequate amounts of selected plant material to bring into cultivation is, however, one of the major issues. Therefore, the in vitro propagation of elite pyrethrum genotypes could be a suitable alternative to conventional propagation methods. In this paper, we present the results of a 9-year field comparison between pyrethrum plants coming from an in vitro propagation protocol and plants obtained by cutting from the same mother plants. Furthermore, since plantlets derived from in vitro regeneration may experience ploidy changes, we evaluated the stability of the ploidy level of pyrethrum-micropropagated plants by flow cytometry (FCM) analysis. FCM screening revealed no differences among the morphotypes and between them and the mother plant. Likewise, the field evaluation of plants gave no significant differences between flower yields in both groups. Hence, micropropagation was confirmed as an easy, efficient and reproducible method to obtain large quantities of selected pyrethrum genotypes.

Water Use and Soil Water Balance of Mediterranean Vineyards under Rainfed and Drip Irrigation Management: Evapotranspiration Partition and Soil Management Modelling for Resource Conservation

Vineyards represent complex Mediterranean agrosystems that deliver significant ecosystem services to society. Yet, many vine-growers still need to assimilate the importance of crop and soil management to the conservation of soil and water resources. The main objective of this study was to evaluate water use and the water balance terms in rainfed and irrigated vineyards in Italy and Portugal, respectively, in both cases aiming at the sustainability of natural resources use. The SIMDualKc model is used for both sites after calibration and validation by fitting soil water content measurements. The Italian case study focused on the impacts of inter-row conservation management in hillslope vineyards while the Portuguese case study analyzed irrigation water management under scarcity in flat vineyards. For the Italian vineyards, the model results focused on the evapotranspiration fluxes and their partition, control of surface runoff, and soil water recharge provided by the inter-row soil management using cover crops. Model results of the Portuguese case study showed the need for improving irrigation water use and the terms of water balance, namely referring to percolation and soil water evaporation. Both case studies further demonstrated the advantages of using computational tools to better cope with climate variability in the Mediterranean region and made evident the benefits of improved crop and soil management practices in counteracting land degradation and valuing the use and conservation of natural resources.

Soil-based automated irrigation for a nectarine orchard in two water availability scenarios

This work studies the feasibility of using automated drip irrigation based on the volumetric soil water content measured with capacitance probes in early maturing nectarine trees (Prunus persica L. Batsch, cv. ‘Flariba’) grown in a clay–loam soil in Mediterranean conditions. An automated irrigation treatment (AUTO), based on the management allowed depletion (MAD) concept (with a feed-back control system), was compared with an irrigation-scheduling method based on the conventional crop evapotranspiration (100% ETc) as Control, under high (HWA) and low (LWA) water availability scenarios, each during three consecutive growing seasons. With HWA (no water restriction), the AUTO treatment maintained the soil water content at near field capacity (α = 10% depletion of available soil water content), and there were no significant differences between treatments in terms of the plant–soil water status, nectarine yield, or fruit quality parameters. Under LWA conditions (water deficit), the AUTO treatment (α = 10% during pre-harvest and 30% post-harvest) provided 43% less water than the Control, promoting a moderate plant water deficit, which led to a decrease in vegetative growth (winter pruning and tree canopy cover) but no significant differences in total yield and fruit quality parameters (although the total soluble solid content increased). The water use efficiency values in the AUTO treatment increased by an average of 34%. It was concluded that automated irrigation, based on MAD seasonal threshold values and monitored by means of real-time soil water content sensors, could be considered a promising tool for application in semi-arid Mediterranean agro-systems subjected to water scarcity.

Long-Term Effects of the Application of Urban Waste Compost and Other Organic Amendments on Solanum tuberosum L.

Background: In a Mediterranean agrosystem of low productivity, a study was carried out on the effects of municipal solid waste compost (MSWC) compared to other organic and inorganic amendments on the production, quality and yield of three potato varieties (Solanum tuberosum L.) and an advanced clone. Method: Simultaneously, the agronomic and nutritional parameters of the potato crop, the degree of bioavailability and the possible risks of heavy metal contamination were studied. Results: Two stages are observed in the yield and content of macro, micronutrients and heavy metals. The addition of all amendments and especially that of urban waste compost increased potato production and the content of macronutrients, micronutrients and heavy metals in the soils of all varieties, showing a progressive accumulation in tubers. Nevertheless, the performance is not maintained over time with a notable decrease during the second stage of its application. Conclusion: Highlighting the potato clone A7677 not only in its performance but also in the concentration of iron, zinc, copper, essential micronutrients for human consumption and especially for populations deficient in these trace elements.

Comparing the effects of soil fauna on litter decomposition and organic matter turnover in sustainably and conventionally managed olive orchards

Soils and crops in Mediterranean agrosystems are vulnerable to climate change and environmental stresses, and they will be more and more in the next future. In this scenario, soil organic matter (SOM) plays a crucial role and its level is principally determined by the continuous physical and chemical action of soil fauna. While the importance of microorganisms in fruit agrosystems has been extensively and recently highlighted, the role of soil fauna - and particularly of macrofauna - to ecosystem services has been often overlooked. On this basis, the aim of this study was to characterize and compare C/N dynamics and other soil physicochemical parameters, soil macrofauna abundance, bioturbation and litter/SOM decomposition indices in a Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (namely sustainable, Smng, and conventional, Cmng) for 18 years. The adoption of the Smng system significantly increased almost three times the abundance of earthworms and two times that of other soil macrofauna. Bioturbation due to soil fauna and roots was significantly higher in the Smng system, and this caused a significantly faster SOM decomposition measured both in 90-day incubated local litter bags (decomposition constant = 0.092 and 0.072 in the Smng and Cmng system, respectively) and in tea bags (decomposition rate constant = 0.018 and 0.010 in the Smng and Cmng system, respectively). Soil C and N dynamics were also affected by different soil management. The results highlighted that the soil chemical quality of the Smng system is the result of the higher abundance and activity of soil fauna, in terms of enhanced litter decomposition and bioturbation. From the general analysis of the data obtained, it emerged that the role of soil fauna should be seriously taken into account in land management strategies not exclusively oriented to fruit yield and quality, but also to soil fertility restoration.

Feeding Ecology and Prey Selection by Wintering Long-Eared Owls Asio otus in Mediterranean Agrosystems

The diet composition and dietary patterns of the Long-eared Owl Asiootus were studied in Mediterranean agrosystems in central Crete (Greece) over the winters of 2009–2015. Overall, 2,819 prey items were recovered from 1,207 pellets, belonging to six taxa of mammals, 22 taxa of birds and four taxa of insects. Small mammals were the most common prey species, accounting for 75.8% by frequency and 79.7% by biomass, followed by birds (23.2% and 20.1%); the latter being rather an island component compared to continental regions. The House Mouse Mus musculus was the most important prey species in the owl's diet (56.3%) ahead of the Wood Mouse apodemus sylvaticus (9.51%) and the Black Rat Rattus rattus (7.9%). The species proved to be a significant rodent predator in olive groves and vineyards during winter months, selecting Wood Mouse and young Black Rat more than expected. Long-eared Owl feeding ecology studies could lead to improved land management and agricultural practices in the rural landscapes of the Mediterranean.

Effects of cover crops on soil biota, soil fertility and weeds, and Pratylenchus suppression in experimental conditions

Summary Cover crops are used in Mediterranean agrosystems to reduce soil degradation and restore soil function. We carried out an experiment to test the effects of two cover crops (Brachypodium distachyon and Trifolium subterraneum, mulched or incorporated) and two bare soil controls (fertilised and unfertilised) on soil properties, biodiversity, and soil natural suppressiveness against Pratylenchus neglectus in pot microcosms. Cover crop performance, weed infestation, litter decomposition rates, soil properties, and the response of soil biota (nematode indicators, mesofauna feeding activity, enzymatic activity, and mycorrhizal spores) were measured. A short-term suppressiveness experiment was performed to determine P. neglectus colonisation of wheat roots after each treatment. Trifolium subterraneum incorporation significantly enhanced the fungal-mediated decomposition channel and decomposition rates, but enzymatic activities and mycorrhizal spore abundances did not respond to the experimental treatments. Cover crops were effective at controlling weeds, but did not increase soil suppressiveness against P. neglectus. Brachypodium distachyon cover cropping increased root infection.

The role of biodiversity data in High Nature Value Farmland areas identification process: A case study in Mediterranean agrosystems

The concept of High Nature Value Farmland (HNVF) was introduced in the early 1990s to highlight the crucial role of low intensity farming systems for the conservation of biodiversity in Europe. HNVF is a biodiversity indicator and the maintenance or the enhancement of HNVF is a goal of the EU’s rural development policy. Several different approaches currently exist for identifying such areas, and a number of studies have shown that outcomes have often been unsatisfactory, at least as concerns biodiversity conservation. In this study, we use birds as indicators to assess the correlation between HNVF types identified according to the land cover approach and farmland areas important for biodiversity in Apulia, a southern Italian region that is among the most important in the Mediterranean area for farmland biodiversity. Our results suggest that unless the current land cover approach – which is mainly based on criteria relating to vegetation types and landscape structure – is accompanied by an objective analysis of local biodiversity levels, it risks excluding from HNVF some of the most important areas for biodiversity, thus reducing indicator effectiveness because of the lack of a proper assessment of HNVF extent and quality. Thus, our study shows a possible method to better identify HNVF type 3, thus increasing the effectiveness of the HNVF indicator.

Managing Mediterranean soil resources under global change: expected trends and mitigation strategies

The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and anthropogenic drivers. These soils are expected to be dramatically affected by future climate and societal changes. These changes imply that suitable adaptive management strategies for these resources cannot simply be transposed from experiments that are performed in other regions of the world. Following a framework that considers the chain of “drivers-soil process-soil capital-ecosystem services/disservices,” the paper review the research undertaken in the Mediterranean area on three types of Mediterranean soil degradation than can be expected under global change: (i) soil losses due to the increase of drought and torrential rainfall; (ii) soil salinization due the increase of droughts, irrigation, and sea level; and (iii) soil carbon stock depletion with the increase of temperature and droughts. The possible strategies for mitigating each of these degradations have been largely addressed and are still studied in current research projects. They should include changes in agricultural practices, soil water management, and vegetal material. As a pre-requisite for the site-specific adaptations of such mitigation strategies within viable Mediterranean agrosystems, it is highlighted that methodological advances are necessary in integrated assessment of agricultural systems and in finer resolution soil mapping.

Strategies for greenhouse gas emissions mitigation in Mediterranean agriculture: A review

An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to irrigation type (drip, sprinkle and furrow) and N fertilization rate (100 and 300kgNha−1yr−1) revealed that these factors may outweigh the reduction in GHG emissions beyond the plot scale. The analysis of the impact of some structural changes on top-down mitigation of GHG emissions revealed that 3–15% of N2O emissions could be suppressed by avoiding food waste at the end-consumer level. A 40% reduction in meat and dairy consumption could reduce GHG emissions by 20–30%. Reintroducing the Mediterranean diet (i.e. ∼35% intake of animal protein) would therefore result in a significant decrease of GHG emissions from agricultural production systems under Mediterranean conditions.

Lateral and depth patterns of soil organic carbon fractions in a mountain Mediterranean agrosystem

SUMMARYThe spatial distribution of soil organic carbon (SOC) can be affected by environmental factors such as land use change, type of vegetation, soil redistribution processes and soil management practices. Because data are scarce in mountain agroecosystems, improving knowledge on the relationships between land use, soil redistribution processes and SOC fractions is of interest, especially in rapidly changing Mediterranean landscapes. Typically, SOC is divided into two distinct carbon fractions: the active and decomposable fraction (ACF) with rapid turnover rates, which acts as a short-term carbon reservoir, and the stable carbon fraction (SCF) with lower turnover rates that acts as a long-term reservoir. In the present study SOC, ACF and SCF contents were measured by the dry combustion method and converted to inventories expressed as mass per unit surface area (kg/m2). The SOC distribution patterns were related to land use and soil redistribution processes in soil profiles along a representative mountain agroecosystem toposequence in northeast Spain. The soil depth profiles were identified as stable, eroded and depositional sites using fallout137caesium (Cs). Significantly higher amounts of SOC were found in forest soils (36 ± 20·2 g/kg) compared to abandoned (21 ± 14·3 g/kg) and cultivated arable land (11 ± 6·3 g/kg), suggesting that cultivation decreases SOC content. In addition, stable soil profiles had significantly higher SOC content (42 ± 24·3 g/kg) than at depositional and eroded profiles (18 ± 14·5 and 17 ± 13·1 g/kg, respectively). A positive and statistically significant relationship between SOC and137Cs inventories suggested that both are moved and associated with similar soil redistribution processes.

Wheat alleles introgress into selfing wild relatives: empirical estimates from approximate Bayesian computation in Aegilops triuncialis.

Extensive gene flow between wheat (Triticum sp.) and several wild relatives of the genus Aegilops has recently been detected despite notoriously high levels of selfing in these species. Here, we assess and model the spread of wheat alleles into natural populations of the barbed goatgrass (Aegilops triuncialis), a wild wheat relative prevailing in the Mediterranean flora. Our sampling, based on an extensive survey of 31 Ae. triuncialis populations collected along a 60 km × 20 km area in southern Spain (Grazalema Mountain chain, Andalousia, totalling 458 specimens), is completed with 33 wheat cultivars representative of the European domesticated pool. All specimens were genotyped with amplified fragment length polymorphism with the aim of estimating wheat admixture levels in Ae. triuncialis populations. This survey first confirmed extensive hybridization and backcrossing of wheat into the wild species. We then used explicit modelling of populations and approximate Bayesian computation to estimate the selfing rate of Ae. triuncialis along with the magnitude, the tempo and the geographical distance over which wheat alleles introgress into Ae. triuncialis populations. These simulations confirmed that extensive introgression of wheat alleles (2.7 × 10(-4) wheat immigrants for each Ae. triuncialis resident, at each generation) into Ae. triuncialis occurs despite a high selfing rate (Fis ≈ 1 and selfing rate = 97%). These results are discussed in the light of risks associated with the release of genetically modified wheat cultivars in Mediterranean agrosystems.

Micromorphological analysis on the influence of the soil mineral composition on short-term aggregation in semi-arid Mediterranean soils .

Aggregation in soils is the result of the interaction of the soil organic components and soil minerals. The reactivity of the mineral phase is acknowledged to interfere with aggregates formation and stabilization, but its influence on aggregation in semi-arid Mediterranean soils remains mostly unknown. In this study, we used micromorphological analysis of aggregates formed in a 28-d incubation in two agricultural soils differing only in the composition of the mineral phase in the upper Ap horizon (a carbonate-depleted Palexeralf with 21.5% clay, and a contiguous carbonate-rich Typic Calcixerept with 20.9% clay before decarbonation which was reduced to 10.4% upon decarbonation). The two soils belong to the same agricultural field and have had similar management for decades. Soil samples were completely disaggregated into their fractions < 250 μm, and incubated with fresh organic matter to stimulate re-aggregation. Macroaggregates (> 2 mm) formed during the incubation were separated at days 3, 7, 14, 21 and 28 and used to prepare thin sections. Macroaggregates were more abundant at day 3, and then decreased in number in the two soils, which indicates a dependency between organic matter decomposition and stable macroaggregates formation. They contained a greater proportion of smaller aggregates in the decarbonated soil. Micromorphological analysis revealed significant differences in the fabric and physical characteristics of these macroaggregates, in which bonds among primary particles were observed to be led by clays in the Palexeralf while the coarse fraction appeared embedded in a micromass with crystallitic b-fabric corresponding to carbonates in the Calcixerept. This resulted in a more compact fabric and less porosity in macroaggregates in the Calcixerept. Image analysis of thin sections was used to quantify and characterize the pore system of macroaggregates. Porosity (pores > 20 μm) was more than double (36.9% for 15.6%) within macroaggregates in the decarbonated soil, with more elongated pores. Although in both soils most pores were 20 to 150-μm in equivalent diameter, some porosity > 150 μm was observed only in macroaggregates from the decarbonated soil. These observations allow hypothesizing that the mechanisms responsible for aggregates stabilization and/or formation are different in the two soils, and that they result in different physical characteristics of soil aggregates. The implications of such differences on air and water flow rates within aggregates, and thus on the soil microbial activity and organic matter decomposition, as well as on soil erodibility, need to be studied and accounted for when evaluating the effect of soil management and other practices on soil quality in semi-arid Mediterranean agrosystems.

Sewage sludge compost use in bioenergy production – a case study on the effects on Cynara cardunculus L energy crop

Abstract As energy obtained from biomass is expected to significantly contribute to the future renewable energy pool, knowledge regarding energy crops management is crucial in order to maximize productivity while establishing positive environmental synergies. In this sense, the application of waste materials as organic amendments represents an interesting option for the growth of energy crops in Mediterranean regions. This is the first three-year trial (2008–2011) that assesses the effect of different sewage sludge compost treatments, applied as basal dressing, on the productivity the energy crop Cynara cardunculus L. (cynara). The experiment was conducted in Alicante (Southeastern Spain), testing four compost application rates: 0, 30, 50 and 70 t ha−1. Cynara yields (dry basis) were higher in the 2010/11 comparatively with 2008/09 for aboveground biomass (2063 vs 1202 g m−2), seed yield (320 vs 153 g m−2), oil yield (81 vs 33 g m−2) and energy yield (37 vs 21 MJ m−2). Concerning fertilisation treatments, composted sludge exerted positive effects, mainly between 50 and 70 t ha−1 application rates, primarily improving the productivity of cynara: aboveground biomass (2195 g m−2) and energy (38 MJ m−2) yields of plants amended with 70 t ha−1 were 68% higher than control plants, while seeds (308 g m−2) and oil yields (103 g m−2) increased by 40%. Therefore, the use of SSC enhanced cynara's productivity (aboveground biomass and seeds yields primarily). The present research provides valuable data to growers and researchers interested in the maximization of environmental positive synergies (soil protection, waste reuse, bioenergy production), as a way to enhance the sustainability of Mediterranean agrosystems.

Soil carbon dynamics as affected by long-term contrasting cropping systems and tillages under semiarid Mediterranean climate

In a dryland Mediterranean agrosystem (Sicily, Italy) a comparative study was carried out among two crop systems (wheat/wheat and wheat/bean) after 19 years under three most used tillage managements (conventional, dual layer and no-tillage), in order to ascertain the effects of those experimental factors, single and combined, on various soil organic C pools (total and extractable organic C, microbial biomass C, basal respiration). Field CO2 fluxes from soil, throughout a year, were also determined. Moreover, C input and output were assessed, as well as microbial and metabolic quotients. Tillage management more than cropping system affected the soil organic C stored in the first 15cm of soil. After 19 years, no-tillage caused a 3.6Mgha−1 increase of C content in wheat/faba rotation while of 5.6Mgha−1 in wheat monoculture. The higher soil total organic C content in wheat monoculture was ascribed to a lower quality of residues supplied (higher both C/N ratio and acid detergent fibre (ADF) content). Moreover, wheat/bean rotation increased soil microbial biomass C, basal respiration and microbial quotient, thus suggesting that crop rotation more than tillage management was the driving factor in improving soil biochemical indicators.

Organic Farming Benefits Local Plant Diversity in Vineyard Farms Located in Intensive Agricultural Landscapes

The majority of research on organic farming has considered arable and grassland farming systems in Central and Northern Europe, whilst only a few studies have been carried out in Mediterranean agro-systems, such as vineyards, despite their economic importance. The main aim of the study was to test whether organic farming enhances local plant species richness in both crop and non-crop areas of vineyard farms located in intensive conventional landscapes. Nine conventional and nine organic farms were selected in an intensively cultivated region (i.e. no gradient in landscape composition) in northern Italy. In each farm, vascular plants were sampled in one vineyard and in two non-crop linear habitats, grass strips and hedgerows, adjacent to vineyards and therefore potentially influenced by farming. We used linear mixed models to test the effect of farming, and species longevity (annual vs. perennial) separately for the three habitat types. In our intensive agricultural landscapes organic farming promoted local plant species richness in vineyard fields, and grassland strips while we found no effect for linear hedgerows. Differences in species richness were not associated to differences in species composition, indicating that similar plant communities were hosted in vineyard farms independently of the management type. This negative effect of conventional farming was probably due to the use of herbicides, while mechanical operations and mowing regime did not differ between organic and conventional farms. In grassland strips, and only marginally in vineyards, we found that the positive effect of organic farming was more pronounced for perennial than annual species.

Identifying erosive periods by using RUSLE factors in mountain fields of the Central Spanish Pyrenees

Abstract. The Mediterranean environment is characterized by strong temporal variations in rainfall volume and intensity, soil moisture and vegetation cover along the year. These factors play a key role on soil erosion. The aim of this work is to identify different erosive periods in function of the temporal changes in rainfall and runoff characteristics (erosivity, maximum intensity and number of erosive events), soil properties (soil erodibility in relation to freeze-thaw processes and soil moisture content) and current tillage practices in a set of agricultural fields in a mountainous area of the Central Pyrenees in NE Spain. To this purpose the rainfall and runoff erosivity (R), the soil erodibility (K) and the cover-management (C) factors of the empirical RUSLE soil loss model were used. The R, K and C factors were calculated at monthly scale. The first erosive period extends from July to October and presents the highest values of erosivity (87.8 MJ mm ha−1 h−1), maximum rainfall intensity (22.3 mm h−1) and monthly soil erosion (0.25 Mg ha−1 month−1) with the minimum values of duration of erosive storms, freeze-thaw cycles, soil moisture content and soil erodibility (0.007 Mg h MJ−1 mm−1). This period includes the harvesting and the plowing tillage practices. The second erosive period has a duration of two months, from May to June, and presents the lowest total and monthly soil losses (0.10 Mg ha−1 month−1) that correspond to the maximum protection of the soil by the crop-cover ($C$ factor = 0.05) due to the maximum stage of the growing season and intermediate values of rainfall and runoff erosivity, maximum rainfall intensity and soil erodibility. The third erosive period extends from November to April and has the minimum values of rainfall erosivity (17.5 MJ mm ha−1 h−1) and maximum rainfall intensity (6.0 mm h−1) with the highest number of freeze-thaw cycles, soil moisture content and soil erodibility (0.021 Mg h MJ−1 mm−1) that explain the high value of monthly soil loss (0.24 Mg ha−1 month−1). The interactions between the rainfall erosivity, soil erodibility, and cover-management factors explain the similar predicted soil losses for the first and the third erosive periods in spite of the strong temporal differences in the values of the three RUSLE factors. The estimated value of annual soil loss with the RUSLE model (3.34 Mg ha−1 yr−1) was lower than the measured value with 137Cs (5.38 Mg ha−1 yr−1) due to the low values of precipitation recorded during the studied period. To optimize agricultural practices and to promote sustainable strategies for the preservation of fragile Mediterranean agrosystems it is necessary to delay plowing till October, especially in dryland agriculture regions. Thus, the protective role of the crop residues will extend until September when the greatest rainfall occurs together with the highest runoff erosivity and soil losses.