Dinámica del uso y cobertura del suelo en las dehesas de Sierra Morena (Parque Natural Sierra Norte de Sevilla, España), 1956-2007

The dehesa, a representative savanna-like ecosystem type, has played and plays an important economic, ecological and social role, in addition to the valuable environmental services that it provides. The present study is focused on the analysis of the changes in the land use /cover of the dehesa in the Sierra Norte de Sevilla Natural Park (Sierra Morena Biosphere Reserve) during the last 50 years. In order to estimate the consequences that the change of land uses and, the activities that are carried out on it have on the dynamics of the dehesa, a diachronic analysis was performed for the period 1956-2007 using the digital geographic information available. The most important changes observed were related to: i) the increase of urban areas, water surface area, reforestation areas, eroded areas, mining areas and dumping sites; and ii) the decrease of cultivation areas, dehesa, scrubland and pastureland. The changing dynamics did not strictly res-pond only to phytosociological aspects, but it is necessary to explain the evolution of the landscape from the complex balance between biophysical and socioeconomic dynamics, where the current environmental changes also make it very difficult to ensure the persistence of this ecosystem. The present legislation promotes the development of a clear and up-to-date diagnosis of the problems that this ecosystem is facing. In this sense, the geographic information systems may be very useful at establishing the guidelines for the conservation and regeneration of the dehesas, and at spreading their environmental values.La dehesa, además de los valiosos servicios ambientales que presta, ha jugado y juega un importante papel económico, ecológico y social. En el presente estudio se analizan los cambios en el uso y cubierta del suelo de las dehesas en el Parque Natural Sierra Norte de Sevilla (Sierra Morena) durante los últimos 50 años. Se realizó un análisis diacrónico para el período 1956-2007 utilizando la información geo-gráfica digital disponible. Los cambios más importantes observados estuvieron relacionados con: i) el incremento de las áreas urbanas, la superficie del agua, áreas de reforestación, áreas erosionadas, áreas de minería y vertederos; y ii) la disminución de las áreas de cultivo, de dehesa, de monte bajo y pastos. Las dinámicas encontradas no respondieron exclusivamente a los aspectos fitosociológicos, pero fueron necesarias para explicar la evolución del paisaje desde el complejo equilibrio entre las dinámicas biofísicas y socioeconómicas, donde también los actuales cambios ambientales hacen que sea muy difícil asegurar la persistencia de este particular ecosistema. La actual le-gislación promueve el desarrollo de un diagnóstico claro de los problemas que este ecosistema enfrenta. En este sentido, los sistemas de información geográfica pueden ser muy útiles en el establecimiento de las directrices para la regeneración y conservación de las dehesas, y en el énfasis de sus valores ambientales.Consejería de Medio Ambiente de la Junta de Andalucía. OG-039/0

Electro-orientation of Ag nanowires in viscoelastic fluids

In this work we study the electro-orientation (through electric birefringence experiments) of silver nanowires in polymer solutions eventually capable of forming gel networks. Information on the structure of the polymer solution is obtained by evaluating the electro-orientation of the nanowires. It is found that in presence of poly(ethylene oxide), Kerr’s law (birefringence proportional to the square of the field) is fulfilled, and the randomization process after switching off the external field is purely diffusive, controlled by the viscosity of the Newtonian polymer solution. In the case of (gelating) sodium alginate solutions, measuring at larger distances from the bottom (where the source of cross-linking Ca2+ ions is deposited) means a smaller degree of cross-linking, and a less stiff gel. In fact, it is found that after a certain time the birefringence signal gets frozen at the bottom, indicating that a gel network is formed which hinders particle orientation. The viscosity deduced up to that point agrees well with rheological determinations, with increasing deviations found at longer times due to the inhomogeneous gel formation. This process has an interesting consequence on birefringence response: Kerr’s law fails to be fulfilled, appearing a ”yield” applied electric field, larger the longer the time after preparation

Dynamical versus statistical downscaling for the generation of regional climate change scenarios at a Western Mediterranean basin: the Jucar River District

[EN] Current climate change (CC) predictions for the Western Mediterranean show a significant increase in temperature, and a decrease in precipitations, with great variability depending on general circulation models (GCM) and downscaling approaches. This paper analyses how dynamic downscaling improves statistically based CC scenarios. The study area was the Jucar River Basin (JB), with results from ECHAM5 GCM, and a close time frame of 2010-2040 appropriated for decision-making. The dynamic downscaling was performed with the regional climate model (RCM) RegCM3. It was applied to a coarse grid over the Iberian Peninsula, and then to a finer grid over the JB. The RCM was customized to reproduce Western Mediterranean climatic conditions using the convective precipitation scheme of Grell; the non-convective scheme was customized by changing the default RHmin and C-ptt parameters to reproduce precipitations originated by larger-scale atmospheric circulations. The RCM results, compared to current official Spanish Agency of Meteorology (AEMET) scenarios-statistically based-reproduce much better historical data (used to verify scenarios generation). They foresee a 21.0% precipitation decrease for 2010-2040, compared to previous ECHAM4 predictions with statistical downscaling (-6.64%). The most significant reductions are in February, September and October. Average estimated temperature increase is 0.75 degrees C, with high increments in July (+3.05 degrees C) and August (+1.89 degrees C).Chirivella Osma, V.; Capilla Romá, JE.; Pérez-Martín, MÁ. (2016). Dynamical versus statistical downscaling for the generation of regional climate change scenarios at a Western Mediterranean basin: the Jucar River District. Journal of Water and Climate Change. 7(2):379-392. doi:10.2166/wcc.2015.207S3793927

Endozoochorus seed dispersal by goats: recovery, germinability and emergence of five Mediterranean shrub species

Herbivores can play an important role as seed dispersal vectors, ungulates constituting potential seed dispersal agents of Mediterranean grasses and shrubs. We evaluated the role of domestic goats as seed dispersers of five representative Mediterranean forage shrub species [Cistus albidus L., Phillyrea angustifolia L., Calicotome villosa (Poir.) Link., Rhamnus lycioides L. and Atriplex halimus L.]. Following seed ingestion by goats, total faeces were collected at 24-h intervals for five days. The total number of seeds recovered varied among species, with R. lycioides showing the minimum recovery percentage (1.3%) and C. albidus (35.8%), the maximum. Seed recovery was significantly related to seed hardness and length. In most species, the maximum amount of seeds recovered occurred 48-72 h after ingestion. The passage through the goat gut significantly depressed seed germination in C. albidus, C. villosa and A. halimus; inhibited it in R. lycioides and increased it in P. angustifolia. Seedling emergence was significantly lower in intact dung pellets than in broken-down ones, and both significantly lower than in uneaten seeds (control). The results of this study show that goats can potentially favor or inhibit seed dispersal of browsed Mediterranean shrub species. Therefore, goat grazing could be a potential management tool for expanding target shrub species populations or preventing shrub encroachment in undesired areas

Índice de perfusión en una reanimación con riesgo biológico, como medida de mala tolerancia fisiológica

Introduction: Perform a cardiopulmonary resuscitation requires technical knowledge and minimal physical conditions. Perform this resuscitation a team of individual protection against biological risks level D placed increases the overexertion that encourage rescuers are subjected.The objective of this study is to prove the existence of a pattern of poor physiological tolerance to the use of personal protective equipment level D, category 4-5-6B for action in incidents with biological risk objectified by measuring the perfusion index before and after a simulated resuscitation.Material and methods: We have performed a quasiexperimental not controlled on 96 volunteers chosen through a random sampling, stratified by sex, level of education and professional category, medical and nursing students and professionals doctors and nurses.A decision of the perfusion index before performing the resuscitation and other simulated after resuscitation.Results: A 15% of the volunteers presented a perfusion index lower back to baseline, which translates into a situation of peripheral vasoconstriction after the completion of the physical exercise that involved the clinical case, when expected was a vasodilatation to Increase perfusion.Conclussion: Extrapolating these data, we can conclude that, in the sample for the study, the volunteers who have less perfusion index at the end of that at the beginning do not tolerate well the effort involved in the case.Introducción: Realizar de una forma adecuada una reanimación cardiopulmonar precisa unos conocimientos técnicos y unas mínimas condiciones físicas. Realizar esta reanimación un equipo de protección individual frente a riesgos biológicos nivel D colocado aumenta el sobresfuerzo al que se ven sometidos los reanimadores.El objetivo de este estudio es comprobar la existencia de un patrón de mala tolerancia fisiológica al uso de los equipos de protección nivel D, categoría 4-5-6B para la actuación en incidentes con riesgo biológico objetivado mediante la medición del índice de perfusión antes y después de una reanimación simulada.Material y métodos: Se ha realizado un estudio cuasiexperimental no controlado sobre 96 voluntarios elegidos mediante un muestreo aleatorio estratificado por sexo, nivel de formación y categoría profesional, estudiantes de Medicina y Enfermería y profesionales Médicos y Enfermeros. Se realizó una toma del índice de perfusión antes de realizar la reanimación y otra después de la reanimación simulada.Resultados: Un 15% de los voluntarios presentaron un índice de perfusión posterior más bajo al basal, lo que se traduce en una situación de vasoconstricción periférica después de la realización del ejercicio físico que supuso el caso clínico, cuando lo esperable era una vasodilatación para aumentar la perfusión.Conclusiones: Extrapolando estos datos, podemos concluir que, en la muestra de estudio que nos ocupa, los voluntarios que presentan menos índice de perfusión al finalizar que al comenzar no toleran bien el esfuerzo que supone el caso clínico. &nbsp