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Garcia-Ruiz J.M.,CSIC - Pyrenean Institute of Ecology | Lopez-Moreno J.I.,CSIC - Pyrenean Institute of Ecology | Vicente-Serrano S.M.,CSIC - Pyrenean Institute of Ecology | Lasanta-Martinez T.,CSIC - Pyrenean Institute of Ecology | Begueria S.,CSIC - Aula Dei Experimental Station
Earth-Science Reviews | Year: 2011

Mediterranean areas of both southern Europe and North Africa are subject to dramatic changes that will affect the sustainability, quantity, quality, and management of water resources. Most climate models forecast an increase in temperature and a decrease in precipitation at the end of the 21st century. This will enhance stress on natural forests and shrubs, and will result in more water consumption, evapotranspiration, and probably interception, which will affect the surface water balance and the partitioning of precipitation between evapotranspiration, runoff, and groundwater flow. As a consequence, soil water content will decline, saturation conditions will be increasingly rare and restricted to periods in winter and spring, and snow accumulation and melting will change, especially in the mid-mountain areas. Future land management will be characterized by forest and shrub expansion in most Mediterranean mountain areas, as a consequence of farmland and grazing abandonment, with increasing human pressure localized only in some places (ski resort and urbanized of valley floors). In the lowlands, particularly in the coastal fringe, increasing water demand will occur as a consequence of expansion of irrigated lands, as well as the growth of urban and industrial areas, and tourist resorts.Future scenarios for water resources in the Mediterranean region suggest (1) a progressive decline in the average streamflow (already observed in many rivers since the 1980s), including a decline in the frequency and magnitude of the most frequent floods due to the expansion of forests; (2) changes in important river regime characteristics, including an earlier decline in high flows from snowmelt in spring, an intensification of low flows in summer, and more irregular discharges in winter; (3) changes in reservoir inputs and management, including lower available discharges from dams to meet the water demand from irrigated and urban areas. Most reservoirs in mountain areas will be subject to increasing water resource uncertainty, because of the reduced influence of snow accumulation and snowmelt processes. Besides, reservoir capacity is naturally reduced due to increasing sedimentation and, in some cases, is also decreased to improve the safety control of floods, leading to a reduction in efficiency for agriculture. And (4) hydrological and population changes in coastal areas, particularly in the delta zones, affected by water depletion, groundwater reduction and saline water intrusion. These scenarios enhance the necessity of improving water management, water prizing and water recycling policies, in order to ensure water supply and to reduce tensions among regions and countries. © 2011 Elsevier B.V. Source

Vicente-Serrano S.M.,CSIC - Pyrenean Institute of Ecology | Begueria S.,CSIC - Aula Dei Experimental Station | Lopez-Moreno J.I.,CSIC - Pyrenean Institute of Ecology
Journal of Climate | Year: 2010

The authors propose a new climatic drought index: the standardized precipitation evapotranspiration index (SPEI). The SPEI is based on precipitation and temperature data, and it has the advantage of combining multiscalar character with the capacity to include the effects of temperature variability on drought assessment. The procedure to calculate the index is detailed and involves a climatic water balance, the accumulation of deficit/surplus at different time scales, and adjustment to a log-logistic probability distribution. Mathematically, the SPEI is similar to the standardized precipitation index (SPI), but it includes the role of temperature. Because the SPEI is based on a water balance, it can be compared to the self-calibrated Palmer drought severity index (sc-PDSI). Time series of the three indices were compared for a set of observatories with different climate characteristics, located in different parts of the world. Under global warming conditions, only the sc-PDSI and SPEI identified an increase in drought severity associated with higher water demand as a result of evapotranspiration. Relative to the sc-PDSI, the SPEI has the advantage of being multiscalar, which is crucial for drought analysis and monitoring. © 2010 American Meteorological Society. Source

Lee Y.,University of Lausanne | Rubio M.C.,University of Lausanne | Rubio M.C.,CSIC - Aula Dei Experimental Station | Alassimone J.,University of Lausanne | Geldner N.,University of Lausanne
Cell | Year: 2013

The precise localization of extracellular matrix and cell wall components is of critical importance for multicellular organisms. Lignin is a major cell wall modification that often forms intricate subcellular patterns that are central to cellular function. Yet the mechanisms of lignin polymerization and the subcellular precision of its formation remain enigmatic. Here, we show that the Casparian strip, a lignin-based, paracellular diffusion barrier in plants, forms as a precise, median ring by the concerted action of a specific, localized NADPH oxidase, brought into proximity of localized peroxidases through the action of Casparian strip domain proteins (CASPs). Our findings in Arabidopsis provide a simple mechanistic model of how plant cells regulate lignin formation with subcellular precision. We speculate that scaffolding of NADPH oxidases to the downstream targets of the reactive oxygen species (ROS) that they produce might be a widespread mechanism to ensure specificity and subcellular precision of ROS action within the extracellular matrix. © 2013 Elsevier Inc. Source

Yruela I.,CSIC - Aula Dei Experimental Station
Metallomics | Year: 2013

Transition metals are involved in essential biological processes in plants since they are cofactors of metalloproteins and also act as regulator elements. Particularly, plant chloroplasts are organelles with high transition metal ion demand because metalloproteins are involved in the photosynthetic electron transport chain. The transition metal requirement of photosynthetic organisms greatly exceeds that of non-photosynthetic organisms, and either metal deficiency or metal excess strongly impacts photosynthetic functions. In chloroplasts, the transition metal ion requirement needs a homeostasis network that strictly regulates metal uptake, chelation, trafficking and storage since under some conditions metals cause toxicity. This review gives an overview of the current understanding of main features concerning the role of copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) in plant photosynthesis as well as the mechanisms involved in their homeostasis within chloroplasts. The metalloproteins functioning in photosynthetic proteins of plants as well as those proteins participating in the metal transport and metal binding assembly are reviewed. Furthermore, the role of nickel (Ni) in artificial photosynthesis will be discussed. © 2013 The Royal Society of Chemistry. Source

Navas A.,CSIC - Aula Dei Experimental Station
Environmental Modelling and Software | Year: 2014

Flow accumulation algorithms (FAAs) predict the cumulative upstream drainage but each FAA generates a different map and this uncertainty still remains unsolved. This study makes advances in flow path research by testing 8 FAAs and analyzing the uncertainties of 15 simulations. The DR2-2013© SAGAv1.0 hydrological software is presented in a study carried out for two catchment lakes (NE Spain) over a 69-month test period. The best simulations were obtained with two single flow (Rho8 and Deterministic Infinity) and two multiple flow (Multiple Flow with threshold value and Triangular Multiple Flow) algorithms. Correlations between runoff depths and lake levels improved when the test period was split into wet and dry seasons. Correlations also improved with a one-month delay in response time and no delay in the large and small lakes. The DR2-2013© tool helped predict changes in lake volume and the highest model efficiencies were obtained with the multiple flow algorithms. © 2014 Elsevier Ltd. Source

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