Perspectives on climate change and human development in the Mediterranean agriculture

The Mediterranean region is one of the world's climate change hotspots. Future climate projections envisage dramatic implications for the agricultural and water sectors that will endanger economic development and lead to natural resources degradation and social instability.

The potential of organic fertilizers and water management to reduce N2O emissions in Mediterranean climate cropping systems. A review.

Environmental problems related to the use of synthetic fertilizers and to organic waste management have led to increased interest in the use of organic materials as an alternative source of nutrients for crops, but this is also associated with N2O emissions. There has been an increasing amount of research into the effects of using different types of fertilization on N2O emissions under Mediterranean climatic conditions, but the findings have sometimes been rather contradictory. Available information also suggests that water management could exert a high influence on N2O emissions. In this context, we have reviewed the current scientific knowledge, including an analysis of the effect of fertilizer type and water management on direct N2O emissions. A meta-analysis of compliant reviewed experiments revealed significantly lower N2O emissions for organic as opposed to synthetic fertilizers (23% reduction). When organic materials were segregated in solid and liquid, only solid organic fertilizer emissions were significantly lower than those of synthetic fertilizers (28% reduction in cumulative emissions). The EF is similar to the IPCC factor in conventionally irrigated systems (0.98% N2O-N N applied−1), but one order of magnitude lower in rainfed systems (0.08%). Drip irrigation produces intermediate emission levels (0.66%). Differences are driven by Mediterranean agro-climatic characteristics, which include low soil organic matter (SOM) content and a distinctive rainfall and temperature pattern. Interactions between environmental and management factors and the microbial processes involved in N2O emissions are discussed in detail. Indirect emissions have not been fully accounted for, but when organic fertilizers are applied at similar N rates to synthetic fertilizers, they generally make smaller contributions to the leached NO3− pool. The most promising practices for reducing N2O through organic fertilization include: (i) minimizing water applications; (ii) minimizing bare soil; (iii) improving waste management; and (iv) tightening N cycling through N immobilization. The mitigation potential may be limited by: (i) residual effect; (ii) the long-term effects of fertilizers on SOM; (iii) lower yield-scaled performance; and (iv) total N availability from organic sources. Knowledge gaps identified in the review included: (i) insufficient sampling periods; (ii) high background emissions; (iii) the need to provide N2O EF and yield-scaled EF; (iv) the need for more research on specific cropping systems; and (v) the need for full GHG balances. In conclusion, the available information suggests a potential of organic fertilizers and water-saving practices to mitigate N2O emissions under Mediterranean climatic conditions, although further research is needed before it can be regarded as fully proven, understood and developed.

Role of maize stover incorporation on nitrogen oxide emissions in a non-irrigated Mediterranean barley field.

Aims Agricultural soils in semiarid Mediterranean areas are characterized by low organic matter contents and low fertility levels. Application of crop residues and/or manures as amendments is a cost-effective and sustainable alternative to overcome this problem. However, these management practices may induce important changes in the nitrogen oxide emissions from these agroecosystems, with additional impacts on carbon dioxide emissions. In this context, a field experiment was carried out with a barley (Hordeum vulgare L.) crop under Mediterranean conditions to evaluate the effect of combining maize (Zea mays L.) residues and N fertilizer inputs (organic and/or mineral) on these emissions. Methods Crop yield and N uptake, soil mineral N concentrations, dissolved organic carbon (DOC), denitrification capacity, N2O, NO and CO2 fluxes were measured during the growing season. Results The incorporation of maize stover increased N2O emissions during the experimental period by c. 105 %. Conversely, NO emissions were significantly reduced in the plots amended with crop residues. The partial substitution of urea by pig slurry reduced net N2O emissions by 46 and 39 %, with and without the incorporation of crop residues respectively. Net emissions of NO were reduced 38 and 17 % for the same treatments. Molar DOC:NO 3 − ratio was found to be a robust predictor of N2O and NO fluxes. Conclusions The main effect of the interaction between crop residue and N fertilizer application occurred in the medium term (4–6 month after application), enhancing N2O emissions and decreasing NO emissions as consequence of residue incorporation. The substitution of urea by pig slurry can be considered a good management strategy since N2O and NO emissions were reduced by the use of the organic residue.

N2O emissions and N efficiency due to tillage systems and crop rotation under a rainfed Mediterranean agroecosystem

Application of nitrogen (N) fertilizers in agricultural soils increases the risk of N loss to the atmosphere in the form of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO)and the water bodies as nitrate (NO3-). The implementation of agricultural management practices can affect these losses. In Mediterranean irrigation systems, the greatest losses of NO3-through leaching occur within the irrigation and the intercropperiod. One way to abate these losses during the intercrop period is the use of cover crops that absorb part of the residual N from the root zone (Gabriel and Quemada, 2011). Moreover, during the following crop, these species could be applied as amendments to the soil, providing both C and N to the soil. This effect of cover and catch crops on decreasing the pool of N potentially lost has focused primarily on NO3-leaching. The aim of this work was to evaluate the effect of cover crops on N2O emission during the in tercrop period in a maize system and its subsequent incorporation into the soil in the following maize crop.

N-Management using Nitrification inhibitor DMPP to Reduce Nitrogen Oxide Emissions in Mediterranean Winter Barley.

Increasing nitrogen (N) use efficiency during crop production is paramount both from an economic and environmental perspective. A proposed measure to achieve it is to split the addition of fertilizers with more than on application. For a winter crop under Mediterranean climatic conditions, the most common application pattern consists of a basal fertilization (October-November) an a top-dressing (February-March).

Summer rainfall variability in European Mediterranean mountains from the sixteenth to the twentieth century reconstructed from tree rings.

En este trabajo se utilizan dendrocronologías para reconstruir la precipitación estival.

Exploring public support for climate change adaptation policies in the Mediterranean region: A case study in Southern Spain.

The understanding of public perception to climate change is an essential factor in the development of adaptation policies. In the Mediterranean, agriculture, as the largest consumer of freshwater, has the highest potential to suffer adverse impacts of climate change. Future water availability predictions, conflicting interests among stakeholders and an increasing social concern about the environment further aggravate the situation. Therefore studying public support for adaptation policies can play a key role in successfully adapting the sector. The study site, approximately 36,000 hectares of rice fields in Seville (Spain), exemplifies an area in the Mediterranean where water needs to be carefully re-allocated in view of the limitations anticipated by climate change scenarios; in particular where conflicts will arise between water for agriculture and water for ‘natural’ ecosystems. This paper proposes an ex-ante evaluation of the societal support for adaptation policies. A survey of 117 respondents was conducted and a Logit model utilized to analyze which predictors positively or negatively affect people's support for adaptation policies. Results suggest that the main barriers to support these policies were economic losses and low climate change concern whereas the primary motivation factor was environmental commitment. Additionally, the main socio-demographic determinants were gender, age, education and family structure. In order to improve societal support for climate change adaptation policies, implementing educational and awareness raising initiatives will be the main challenges for policy makers to overcome.

A model of economic management of cultural heritage: the rehabilitation of fort christmas as an interpretation center of defensive architecture of the Mediterranean in Cartagena (Spain)

The Cultural Heritage constitutes a way to generate social identities and play an important role in the development of the Spanish Mediterranean cities that opt to sustainable quality tourism. The reflection on the necessity of intervention on this heritage, in addition to establishing what should be done, brings up the need to define the reasons for taking action, why and what-for. These decisions are essential to establish if its maintenance and recovery are economically sustainable. The Project "Cartagena Port of Cultures", with support from the European Union, is an example of effective instrument for ensuring the sustainability of our built heritage conservation. Its main objective was to enable sustainable development of tourism in Cartagena based on sustainability and seasonality. This was achieved through a process of recovery of heritage resources and their optimum promotion and marketing.

Aridity modulates N availability in arid and semiarid Mediterranean grasslands

While much is known about the factors that control each component of the terrestrial nitrogen (N) cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC) on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia), including both biotic (e.g. plant cover) and abiotic (e.g. soil OC and pH). If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

On the importance of shrub encroachment by sprouters, climate, species richness and anthropic factors for ecosystem multifunctionality in semi-arid Mediterranean ecosystems

One of the most important changes taking place in drylands worldwide is the increase of the cover and dominance of shrubs in areas formerly devoid of them (shrub encroachment). A large body of research has evaluated the causes and consequences of shrub encroachment for both ecosystem structure and functioning. However, there are virtually no studies evaluating how shrub encroachment affects the ability of ecosystems to maintain multiple functions and services simultaneously (multifunctionality). We aimed to do so by gathering data from ten ecosystem functions linked to the maintenance of primary production and nutrient cycling and storage (organic C, activity of β-glucosidase, pentoses, hexoses, total N, total available N, amino acids, proteins, available inorganic P, and phosphatase activity), and summarizing them in a multifunctionality index (M). We assessed how climate, species richness, anthropic factors (distance to the nearest town, sandy and asphalted road, and human population in the nearest town at several historical periods) and encroachment by sprouting shrubs impacted both the functions in isolation and M along a regional (ca. 350 km) gradient in Mediterranean grasslands and shrublands dominated by a non-sprouting shrub. Values of M were higher in those grasslands and shrublands containing sprouting shrubs (43 and 62%, respectively). A similar response was found when analyzing the different functions in isolation, as encroachment by sprouting shrubs increased functions by 2–80% compared to unencroached areas. Encroachment was the main driver of changes in M along the regional gradient evaluated, followed by anthropic factors and species richness. Climate had little effects on M in comparison to the other factors studied. Similar responses were observed when evaluating the functions in isolation. Overall, our results showed that M was higher at sites with higher sprouting shrub cover, longer distance to roads and higher perennial plant species richness. Our study is the first documenting that ecosystem multifunctionality in shrublands is enhanced by encroaching shrubs differing in size and leaf attributes. Our findings reinforce the idea that encroachment effects on ecosystem functioning cannot be generalized, and that are largely dependent on the traits of the encroaching shrub relative to those of the species being replaced.

Land Cover Mapping by an Optimized Object-Oriented Approach. Case of Study Mediterranean Landscapes

Remote sensing information from spaceborne and airborne platforms continues to provide valuable data for different environmental monitoring applications. In this sense, high spatial resolution im-agery is an important source of information for land cover mapping. For the processing of high spa-tial resolution images, the object-based methodology is one of the most commonly used strategies. However, conventional pixel-based methods, which only use spectral information for land cover classification, are inadequate for classifying this type of images. This research presents a method-ology to characterise Mediterranean land covers in high resolution aerial images by means of an object-oriented approach. It uses a self-calibrating multi-band region growing approach optimised by pre-processing the image with a bilateral filtering. The obtained results show promise in terms of both segmentation quality and computational efficiency.

Current ozone levels threaten gross primary production and yield of Mediterranean annual pastures and nitrogen modulates the response

Pastures are among the most important ecosystems in Europe considering their biodiversity and dis- tribution area. However, their response to increasing tropospheric ozone (O 3 ) and nitrogen (N) deposi- tion, two of the main drivers of global change, is still uncertain. A new Open-Top Chamber (OTC) experiment was performed in central Spain, aiming to study annual pasture response to O 3 and N in close to natural growing conditions. A mixture of six species of three representative families was sowed in the fi eld. Plants were exposed for 40 days to four O 3 treatments: fi ltered air, non- fi ltered air (NFA) repro- ducing ambient levels and NFA supplemented with 20 and 40 nl l � 1 O 3 . Three N treatments were considered to reach the N integrated doses of “ background ” , þ 20 or þ 40 kg N ha � 1 . Ozone signi fi cantly reduced green and total aboveground biomass (maximum reduction 25%) and increased the senescent biomass (maximum increase 40%). Accordingly, O 3 decreased community Gross Primary Production due to both a global reduction of ecosystem CO 2 exchange and an increase of ecosystem respiration. Nitrogen could partially counterbalance O 3 effects on aboveground biomass when the levels of O 3 were moderate, but at the same time O 3 exposure reduced the fertilization effect of higher N availability. Therefore, O 3 must be considered as a stress factor for annual pastures in the Mediterranean areas.

Crop rotation and residues influence N2O emission and N efficiency rather than tillage under a rainfed Mediterranean agroecosystem

Conservation tillage and crop rotation have spread during the last decades because promotes several positive effects (increase of soil organic content, reduction of soil erosion, and enhancement of carbon sequestration) (Six et al., 2004). However, these benefits could be partly counterbalanced by negative effects on the release of nitrous oxide (N2O) (Linn and Doran, 1984). There is a lack of data on long-term tillage system study, particularly in Mediterranean agro-ecosystems. The aim of this study was to evaluate the effects of long-term (>17 year) tillage systems (no tillage (NT), minimum tillage (MT) and conventional tillage (CT)); and crop rotation (wheat (W)-vetch (V)-barley (B)) versus wheat monoculture (M) on N2O emissions. Additionally, Yield-scaled N2O emissions (YSNE) and N uptake efficiency (NUpE) were assessed for each treatment.

Stem CO2 efflux and its contribution to ecosystem CO2 efflux decrease with drought in a Mediterranean forest stand

tThe rate of metabolic processes demanding energy in tree stems changes in relation with prevailing cli-matic conditions. Tree water availability can affect stem respiration through impacts on growth, phloemtransport or maintenance of diverse cellular processes, but little is known on this topic. Here we moni-tored seasonal changes in stem CO2efflux (Fs), radial growth, sap flow and non-structural carbohydrates intrees of Quercus ilex in a Mediterranean forest stand subjected since 2003 to either partial (33%) through-fall exclusion (E) or unchanged throughfall (C). Fsincreased exponentially during the day by an effectof temperature, although sap flow attenuated the increase in Fsduring the day time. Over the year, Fsalso increased exponentially with increasing temperatures, but Fscomputed at a standard temperatureof 15?C (F15s) varied by almost 4-fold among dates. F15swas the highest after periods of stem growth anddecreased as tree water availability decreased, similarly in C and E treatments. The decline in F15swas notlinked to a depletion of soluble sugars, which increased when water stress was higher. The proportionof ecosystem respiration attributed to the stems was highest following stem growth (23.3%) and lowestduring the peak of drought (6.5%). High within-year variability in F15smakes unadvisable to pool annualdata of Fsvs. temperature to model Fsat short time scales (hours to months) in Mediterranean-type for-est ecosystems. We demonstrate that water availability is an important factor governing stem CO2effluxand suggest that trees in Mediterranean environments acclimate to seasonal drought by reducing stemrespiration. Stem respiratory rates do not seem to change after a long-term increase in drought intensity,however.

Modelización de servicios ecosistémicos en una cuenca hidrológica del área mediterránea = Modeling ecosystem services in a mediterranean area river basin

La modelización es un proceso por el que se obtienen modelos de los procesos del ´mundo real´ mediante la utilización de simplificaciones. Sin embargo, las estimaciones obtenidas con el modelo llevan implícitas incertidumbre que se debe evaluar. Mediante un análisis de sensibilidad se puede mejorar la confianza en los resultados, sin embargo, este paso a veces no se realiza debido básicamente al trabajo que lleva consigo este tipo de análisis. Además, al crear un modelo, hay que mantener un equilibrio entre la obtención de resultados lo más exactos posible mediante un modelo lo más sencillo posible. Por ello, una vez creado un modelo, es imprescindible comprobar si es necesario o no incluir más procesos que en un principio no se habían incluido. Los servicios ecosistémicos son los procesos mediante los cuales los ecosistemas mantienen y satisfacen el bienestar humano. La importancia que los servicios ecosistémicos y sus beneficios asociados tienen, junto con la necesidad de realizar una buena gestión de los mismos, han estimulado la aparición de modelos y herramientas para cuantificarlos. InVEST (Integrated Valuation of Ecosystem Services and Tradoffs) es una de estas herramientas específicas para calcular servicios eco-sistémicos, desarrollada por Natural Capital Project (Universidad de Stanford, EEUU). Como resultado del creciente interés en calcular los servicios eco-sistémicos, se prevé un incremento en la aplicación del InVEST. La investigación desarrollada en esta Tesis pretende ayudar en esas otras importantes fases necesarias después de la creación de un modelo, abarcando los dos siguientes trabajos. El primero es la aplicación de un análisis de sensibilidad al modelo en una cuenca concreta mediante la metodología más adecuada. El segundo es relativo a los procesos dentro de la corriente fluvial que actualmente no se incluyen en el modelo mediante la creación y aplicación de una metodología que estudiara el papel que juegan estos procesos en el modelo InVEST de retención de nutrientes en el área de estudio. Los resultados de esta Tesis contribuirán a comprender la incertidumbre involucrada en el proceso de modelado. También pondrá de manifiesto la necesidad de comprobar el comportamiento de un modelo antes de utilizarlo y en el momento de interpretar los resultados obtenidos. El trabajo en esta Tesis contribuirá a mejorar la plataforma InVEST, que es una herramienta importante en el ámbito de los servicios de los ecosistemas. Dicho trabajo beneficiará a los futuros usuarios de la herramienta, ya sean investigadores (en investigaciones futuras), o técnicos (en futuros trabajos de toma de decisiones o gestión ecosistemas). ABSTRACT Modeling is the process to idealize real-world situations through simplifications in order to obtain a model. However, model estimations lead to uncertainties that have to be evaluated formally. The role of the sensitivity analysis (SA) is to assign model output uncertainty based on the inputs and can increase confidence in model, however, it is often omitted in modelling, usually as a result of the growing effort it involves. In addition, the balance between accuracy and simplicity is not easy to assess. For this reason, when a model is developed, it is necessary to test it in order to understand its behavior and to include, if necessary, more complexity to get a better response. Ecosystem services are the conditions and processes through which natural ecosystems, and their constituent species, sustain and fulfill human life. The relevance of ecosystem services and the need to better manage them and their associated benefits have stimulated the emergence of models and tools to measure them. InVEST, Integrated Valuation of Ecosystem Services and Tradoffs, is one of these ecosystem services-specific tools developed by the Natural Capital Project (Stanford University, USA). As a result of the growing interest in measuring ecosystem services, the use of InVEST is anticipated to grow exponentially in the coming years. However, apart from model development, making a model involves other crucial stages such as its evaluation and application in order to validate estimations. The work developed in this thesis tries to help in this relevant and imperative phase of the modeling process, and does so in two different ways. The first one is to conduct a sensitivity analysis of the model, which consists in choosing and applying a methodology in an area and analyzing the results obtained. The second is related to the in-stream processes that are not modeled in the current model, and consists in creating and applying a methodology for testing the streams role in the InVEST nutrient retention model in a case study, analyzing the results obtained. The results of this Thesis will contribute to the understanding of the uncertainties involved in the modeling process. It will also illustrate the need to check the behavior of every model developed before putting them in production and illustrate the importance of understanding their behavior in terms of correctly interpreting the results obtained in light of uncertainty. The work in this thesis will contribute to improve the InVEST platform, which is an important tool in the field of ecosystem services. Such work will benefit future users, whether they are researchers (in their future research), or technicians (in their future work in ecosystem conservation or management decisions).