Spatio-temporal modelling of stable isotopes in tree Mediterranean species (Quercus ilex L. and Pinus Halepensis Mill.): a climatic and ecophysiological view

Trees hold important secrets that may be essential in order to face the unprecedented current environmental challenges. The basis of this thesis is to use a combination of modern tools such as stable isotopes, Geographical Information Systems (GIS), Point Process statistics to retrieve climatic and ecophysiological information from forests at different spatial and temporal scales. We focus on two typical coexisting Mediterranean species: holm oak (Quercus ilex L.) and Aleppo pine (Pinus halepensis Mill.). At the regional scale: we generated carbon isotope (D13C) landscapes (isoscapes) of each species, later converted to annual precipitation maps: and we also showed that in Aleppo pine, annual precipitation drives D13C, RG and NDVI, but the three variables hold complementary information. At the local scale, we focus on a mixed forest stand in which both species coexist. By combining water isotopes and point process statistics, we could interpret tree-to-tree interactions in terms of water use (including seasonal variation).We found evidences of a dynamic niche segregation.Los árboles poseen secretos importantes que pueden ser esenciales para afrontar los actuales retos medioambientales. La idea central de esta tesis es usar una combinación de herramientas modernas, tales como Sistemas de Información Geográfica (SIG), estadística de Procesos Puntuales, para extraer información de los bosques a diferentes escalas espaciotemporales. Nos centramos en dos especies mediterráneas: la encina (Quercus ilex L.) y el pino carrasco (Pinus halepensis Mill.). A escala regional, generamos paisajes de distribución isotópica (isoscapes) de carbono (D13C) para cada especie, derivando así mapas de precipitación anual; mostramos que la precipitación controla la variabilidad espaciotemporal de la D13C, crecimiento radial (CR) e índice de vegetación (NDVI) para el pino, aunque ofrecen información complementaria. A escala local, nos centramos en una masa mixta donde ambas especies coexisten. Combinando isótopos de agua y estadística de Procesos Puntuales, interpretamos las interacciones árbol-árbol en el uso de agua (incluyendo variación estacional). Encontramos evidencias de una segregación de nicho hidrológico dinàmica.Els arbres amaguen secrets importants que poden ser essencials per enfrontar-se als actuals canvis ambientals sense precedents. El fonament d’aquesta tesi és fer servir una combinació d’eines innovadores com ara isòtops estables, Sistemes d’Informació Geogràfica (SIG), o estadística de processos puntuals a fi d’obtenir informació climàtica i ecofisiològica dels boscos a diferents escales temporals i espacials. L’objecte d’estudi són dues espècies típicament mediterrànies: alzina (Quercus ilex L.) i pi blanc (Pinus halepensis Mill) A escala regional, generem paisatges de distribució isotòpica (isoscapes) de (D13C) per cada espècie; trobem que la variació espacial i temporal en D13C, creixement radial (CR) i els índexs de vegetació (NDVI) pel pi blanc, ve donat per la precipitació anual, encara que ofereixen informació complementària. A escala local, ens centrem en una massa mixta on les dues espècies coexisteixen. Combinant isòtops d’aigua i estadística de processos puntuals hem pogut interpretar interaccions arbre-arbre en l’ús de l’aigua (incloent variació estacional). Trobem evidències d’una segregació de nínxol hidrològic dinàmica

Point processes statistics of stable isotopes: analysing water uptake patterns in a mixed stand of Aleppo pine and Holm oak

Aim of study: Understanding inter- and intra-specific competition for water is crucial in drought-prone environments. However, little is known about the spatial interdependencies for water uptake among individuals in mixed stands. The aim of this work was to compare water uptake patterns during a drought episode in two common Mediterranean tree species, Quercus ilex L. and Pinus halepensis Mill., using the isotope composition of xylem water (δ18O, δ2 H) as hydrological marker. Area of study: The study was performed in a mixed stand, sampling a total of 33 oaks and 78 pines (plot area= 888 m2 ). We tested the hypothesis that both species uptake water differentially along the soil profile, thus showing different levels of tree-to-tree interdependency, depending on whether neighbouring trees belong to one species or the other. Material and Methods: We used pair-correlation functions to study intra-specific point-tree configurations and the bivariate pair correlation function to analyse the inter-specific spatial configuration. Moreover, the isotopic composition of xylem water was analysed as a mark point pattern. Main results: Values for Q. ilex (δ18O = –5.3 ± 0.2‰, δ2 H = –54.3 ± 0.7‰) were significantly lower than for P. halepensis (δ18O = –1.2 ± 0.2‰, δ2 H = –25.1 ± 0.8‰), pointing to a greater contribution of deeper soil layers for water uptake by Q. ilex. Research highlights: Point-process analyses revealed spatial intra-specific dependencies among neighbouring pines, showing neither oak-oak nor oak-pine interactions. This supports niche segregation for water uptake between the two species.This work was funded by the Projects SMARTREES (FP7-PEOPLE-2009-RG-246725, EU) and RESILFOR (AGL 2012-40039-C02-02, MEC, and Spain). JPF and JdC were supported by the Ramon y Cajal programme (MEC, Spain), and a FPI fellowship (MEC, Spain), respectively

Oak Competition Dominates Interspecific Interactions in Growth and Water-Use Efficiency in a Mixed Pine-Oak Mediterranean Forest

In the Mediterranean, mixed forests of Aleppo pine and holm oak are widespread. Generally considered a transition stage in the succession towards climax oak communities, niche segregation may also contribute to the prevalence of these communities. So far, there is increasing evidence of hydrological niche segregation, with the two species showing complementary water use and seasonal growth patterns. However, it remains unknown whether interspecific interactions affect the response to climate and the mid-term (decadal) growth and water-use efficiency of pines and oaks in mixed stands. Here, we combined tree-ring chronologies, built on different competition classes within a mixed stand, with a spatially explicit assessment of individual growth and wood carbon isotope discrimination (∆13C), as a proxy of intrinsic water-use efficiency, and compared these results with previously reported water uptake patterns. We found that competition with pines modulated the climate response of oaks, whereas pine climate response was insensitive to competition. On the other hand, pine density affected only pine growth, whereas oak competition affected both species. We conclude that the presence of pines had negligible or even positive effects on the oaks, but competition with neighbor oaks limited their ability to recover after drought. Conversely, pines experienced greater drought stress under competition, with both oaks and pinesThis research was funded by the Spanish Government through Projects CGL2011-26654 and RTI2018-094691-B-C31 (MCIU/AEI/FEDER, EU). J.P.F. was supported by Reference Group H09_20R (Gobierno de Aragón, Spain)

Requisitos para a valoração de riscos de preservação em repositórios digitais

Objective. The present article approaches in a succinct way to some theoretical considerations about the preservation and the risk management in digital repositories. In that sense, three key international experiences are presented, in order to assess risks in the digital environment and to offer a set of general requirements that should be taken into account for the assessment of preservation risks in digital repositories.Method. We used the classic documentary analysis of an extensive specialized bibliography on the subject. Likewise, the classic documentary analysis was very useful for the understanding of the three international experiences of risk assessment in digital repositories that are presented.Results. The main result was a set of ten general requirements that should be taken into account for the assessment of preservation risks in digital repositories.Conclusions. The results obtained make it possible to assess the reliability, authenticity and integrity of your resources through the identification of threats in the components of your system, your community of users and your organizational environment.Objetivo. El presente artículo se propone abordar de manera suscinta algunas consideraciones teóricas en torno a la preservación y la gestión de riesgos en repositorios digitales. En este sentido, se presentan tres experiencias internacionales clave, orientadas a la valoración de riesgos en ambiente digital, para luego ofrecer un conjunto de requisitos generales que deberían tenerse en cuenta para la valoración de riesgos de preservación en repositorios digitalesMétodo. Se utilizó el análisis documental clásico de una extensa bibliografía especializada sobre el tema que se aborda en este artículo. Asimismo, el análisis documental clásico fue de gran utilidad para la comprensión de las tres experiencias internacionales de valoración de riesgos en repositorios digitales que se presentan.Resultados. El principal resultado fue un conjunto de diez requisitos generales que deberían tenerse en cuenta para la valoración de riesgos de preservación en repositorios digitales.Conclusiones. Los resultados obtenidos permiten valorar la confiabilidad, autenticidad e integridad de sus recursos a través de la identificación de amenazas en los componentes de su sistema, su comunidad de usuarios y su ambiente organizacional.Objetivo. O presente artigo propõe-se abordar de maneira suscinta algumas considerações teóricas em torno da preservação e o gerenciamento de riscos em repositórios digitais. Neste sentido, apresentam-se três experiências internacionais chave, orientadas à valoração de riscos em ambiente digital, para depois oferecer um conjunto de requisitos gerais que deveriam ser tido em conta para a valoração de riscos de preservação em repositórios digitaisMétodo. Utilizou-se a análise documentária clássico de uma extensa bibliografia especializada sobre o tema que se aborda neste artigo. Assim mesmo, a análise documentária clássico foi de grande utilidade para o entendimento das três experiências internacionais de valoração de riscos em repositorios digitais que se apresentam.Resultados. O principal resultado foi um conjunto de dez requisitos gerais que deveriam ser tido em conta para a valoração de riscos de preservação em repositórios digitais.Conclusões. Os resultados obtidos permitem valorizar a confiabilidade, autenticidade e integridade de seus recursos mediante a identificação de ameaças nos componentes de seu sistema, sua comunidade de usuários e seu ambiente organizacional

Proposal to Foster Sustainability through Circular Economy-Based Engineering: A Profitable Chain from Waste Management to Tunnel Lighting

The increasing demands of infrastructures in terms of energy consumption, raw material demand, greenhouse gas emissions, waste management, treatment of components after their lifetime period, and financial costs are nowadays a serious threat for sustainability. Given that the resources are limited, it is difficult to ensure an accurate level of well-being for future generations. For this reason, new perspectives in design, production and consumption are necessary. In this work, the principles of circular economy are applied to concrete branches of engineering. Departing from a design orientated to new uses after life period of infrastructures, a circular economy-aimed engineering makes possible the connection and mutual profit of such different branches like waste management and tunnel lighting. The benefits in environmental and financial terms are a strong argument in favor of a stronger link between engineering and circular economy.This study has been supported and co-financed by projects from the Spanish Ministry of Economy and Competitiveness ECO2010-15885 and ECO2013-47027-P, Andalusian Government P11-SEJ-7294 and European Union (ERDF funds)

Experiencia con Sildenafil oral en pacientes hemodializados. Estudio multicentro

La Disfunción Sexual Eréctil (DSE) está presente en la Enfermedad Renal Crónica Terminal, siendo de naturaleza multifactorial el empleo del Sildenafil, documentado en diversos trabajos internacionales. Este estudio tuvo como objetivo evaluar la evolución de la DSE, según el Indice Internacional de Función Eréctil-5 (IIFE-5), después del tratamiento con Sildenafil, así como su eficacia y seguridad en pacientes en hemodiálisis por vez primera en nuestro país. Se trata de un estudio cuasi-experimental, no controlado en 22 pacientes,  previo consentimiento informado, con edad entre 18-60 años, hemodiálisis por más de 6 meses y  pareja sexual (femenina) estable de más de 6 meses. Se excluyeron enfermos con antecedentes  personales de infarto miocardio, angina, anemia severa y hepatopatía. Se administró 50 mgs de Sildenafil (Activin), 2 veces por semana, durante  4 semanas, al final de las cuales se volvió a aplicar el IIFE-5, reclasificándose la DSE; además se recogieron los eventos adversos señalados en la literatura en relación con el fármaco en estudio. Como resultados, obtuvimos: Edad 43,5 ± 6,2años, enfermedad causal: diabetes 36,4%,  hipertensión 31,8%,  tiempo en hemodiálisis de 5,8 ± 4,2 años. Sildenafil fue asociado a la mejoría de la puntuación en los cinco dominios explorados con el IIFE-5. Se observó la mejoría  de la DSE en 81,8% del total de los enfermos. Los diabéticos, seguidos de los hipertensos, presentaron mayor severidad de la DSE que el resto de los pacientes, así como menor mejoría global del puntaje al final del tratamiento (p<0.001). Los eventos adversos se presentaron en 54,5% de los enfermos, con carácter leve y transitorio: cefalea (30%), rubor (27,5%) y congestión nasal (24%). Como conclusión tenemos que el Sildenafil oral en estos pacientes hemodializados con DSE se comportó de manera efectiva y segura.  Palabras clave: Disfunción sexual eréctil,  hemodiálisis, índice internacional de función eréctil-5,  Sildenafil

Circadian rhythms regulate the environmental responses of net CO2 exchange in bean and cotton canopies

Studies on the dependence of the rates of ecosystem gas exchange on environmental parameters often rely on the up-scaling of leaf-level response curves ('bottom-up' approach), and/or the down-scaling of ecosystem fluxes ('top-down' approach), where one takes advantage of the natural diurnal covariation between the parameter of interest and photosynthesis rates. Partly independent from environmental variation, molecular circadian clocks drive ∼24 h oscillations in leaf-level photosynthesis, stomatal conductance and other physiological processes in plants under controlled laboratory conditions. If present and of sufficient magnitude at ecosystem scales, circadian regulation could lead to different results when using the bottom-up approach (where circadian regulation exerts a negligible influence over fluxes because the environment is modified rapidly) relative to the top-down approach (where circadian regulation could affect fluxes as it requires the passage of a few hours). Here we dissected the drivers of diurnal net CO2 exchange in canopies of an annual herb (bean) and of a perennial shrub (cotton) through a set of experimental manipulations to test for the importance of circadian regulation of net canopy CO2 exchange, relative to that of temperature and vapor pressure deficit, and to understand whether circadian regulation could affect the derivation of environmental flux dependencies. Contrary to conventional wisdom, we observed how circadian regulation exerted controls over net CO2 exchange that were of similar magnitude to the controls exerted by direct physiological responses to temperature and vapor pressure deficit. Diurnal patterns of net CO2 exchange could only be explained by considering effects of environmental responses combined with circadian effects. Consequently, we observed significantly different results when inferring the dependence of photosynthesis over temperature and vapor pressure deficit when using the top-down and the bottom up approaches.We remain indebted to E. Gerardeau, D. Dessauw, J. Jean, P. Prudent (Aïda CIRAD), J.-J. Drevon, C. Pernot (Eco&Sol INRA), B. Buatois, A. Rocheteau (CEFE CNRS), A. Pra, A. Mokhtar and the full Ecotron team, in particular C. Escape, for outstanding technical assistance during experiment set-up, plant cultivation and measurements. Earlier versions of the manuscript benefitted from comments by M. Dietze, B. Medlyn, R. Duursma and Y.-S. Lin. This study benefited from the CNRS human and technical resources allocated to the ECOTRONS Research Infrastructures as well as from the state allocation ‘Investissement d'Avenir’ ANR-11-INBS-0001, ExpeER Transnational Access program, Ramón y Cajal fellowships (RYC-2012-10970 to VRD and RYC-2008-02050 to JPF), the Erasmus Mundus Master Course Mediterranean Forestry and Natural Resources Management (MEDfOR) and internal grants from UWS-HIE to VRD and ZALF to AG. We thank the Associate Editor T. Vesala and two anonymous reviewers for their help to improve this manuscript