Sobre algunas plantas de las Yeseras de Almería

Se ofrecen datos corológicos y ecológicos sobre algunos táxones de interés de la flora gipsícola almeriense. Quince táxones pueden haberse citado por primera vez en la provincia.Corological and ecological data of some interesting taxa of the gypsum flora from Almería province are presented. Fifteen taxa are probably cited at the first time for Almería province (SE of Spain)

Functional ecology of the biological soil crust in semiarid SE Spain: sun and shade populations of Diploschistes diacapsis (Ach.) Lumbsch

The Tabernas badlands in semiarid south-east Spain is one of the driest regions in Europe with a mean annual precipitation of c. 240 mm. The landscape is deeply dissected, with canyons, ramblas and sparsely vegetated eroded badland slopes. The vegetation is predominantly a biological soil crust consisting of different types of lichen-rich communities, one of the more conspicuous being dominated by Diploschistes diacapsis (Ach.) Lumbsch. This lichen is mainly restricted to the north- facing slopes, where it forms extensive whitish carpets and probably plays an important role in preventing erosion of the slopes and allowing plant colonization. South-facing slopes are much more eroded and generally lack vegetation. %The photosynthetic performance of north (shade) and south-facing (sun) populations of D. diacapsis was studied to determine if these different populations showed any adaptations to the microclimatic conditions of their individual habitats. The response of CO2 exchange to light intensity, temperature and water content was measured under controlled conditions in the laboratory. Dry weight-based net photosynthetic rates were higher in the southern-exposed population but quantum efficiency, and light compensation points were similar. Thallus weight per unit area (LMA) was considerably higher for shade specimens but maximum water content and optimal water content were very similar and chlorophyll content on a dry weight basis was also similar. Chlorophyll content on an area basis was higher in the northern-exposed population and always much larger than those reported in other studies on the same species (up to 8 times larger) with the result that NP values on a chlorophyll basis were relatively low. The larger LMA meant that shade thalli stored more water per unit area which should ensure longer active periods than sun thalli. The results support a strategy pair of high NP and short active time versus low NP and long active time, both having been reported for other soil crust species. However, the visibly larger biomass of the shade D. diacapsis suggests that the lichen is at the limit of its adaptability in these habitats

Water vapor adsorption by dry soils: A potential link between the water and carbon cycles

Water vapor adsorption (WVA) by soil is a potential contributor to the water cycle in drylands. However, continuous in-situ estimates of WVA are still scarce and the understanding of its coupling with carbon cycle and ecosystem processes remains at an incipient stage. Here we aimed to (1) identify periods of WVA and improve the understanding of the underlying processes involved in its temporal patterns by using the gradient method; (2) characterize a potential coupling between water vapor and CO2 fluxes, and (3) explore the effect of soil properties and biocrusts ecological succession on fluxes. We assumed that the nocturnal soil CO2 uptake increasingly reported in those environments could come from WVA enhancing geochemical reactions involving calcite. We measured continuously during ca. 2 years the relative humidity and CO2 molar fraction in soil and atmosphere, in association with below- and aboveground variables, over the biocrusts ecological succession. We estimated water vapor and CO2 fluxes with the gradient method, and cumulative fluxes over the study. Then, we used statistical modelling to explore relationships between variables. Our main findings are (1) WVA fluxes during hot and dry periods, and new insights on their underlying mechanisms; (2) a diel coupling between water vapor and CO2 fluxes and between cumulative fluxes, well predicted by our models; and (3) cumulative CO2 influxes increasing with specific surface area in early succession stages, thus mitigating CO2 emissions. During summer drought, as WVA was the main water source, it probably maintained ecosystem processes such as microbial activity and mineral reactions in this dryland. We suggest that WVA could drive the nocturnal CO2 uptake in those moments and discuss biogeochemical mechanisms potentially involved. Additional research is needed to monitor soil water vapor and CO2 uptake and separate their biotic and abiotic components as those sinks could grow with climate change.Departamento de Física Aplicad

Efecto de antígenos de Clostridium perfringens y ácido retinoico sobre la expresión de IgA en la mucosa intestinal de crías de alpacas (Vicugna pacos)

Publicación a texto completo no autorizada por el autorEl documento digital no refiere asesorCompara los niveles de expresión relativa del gen del exón 1 de la IgA en el epitelio intestinal de las crías de alpacas tratadas y no tratados por vía oral con antígenos de Clostridium perfringens mas All -trans Ácido Retinoico (ATRA). Se muestrearon 32 animales: 14 tratados (6 de 1 día de edad y 8 entre 7 a 14 días de edad) y 18 no tratadas (10 de 1 día de edad y 8 entre 7 a 14 días de edad). Las muestras tomadas correspondieron a 2 cm de yeyuno, la cual fue congelada en nitrógeno líquido a -196°C. A su arribo en el laboratorio se realizó la extracción de ARN total con Trizol® siguiendo las indicaciones del fabricante, luego se sintetizó ADN complementario (ADNc). Posteriormente se realizó la PCR convencional y la técnica de RT- PCR Tiempo Real empleando oligonucleótidos diseñados para la detección del exón 1 de la región Fc IgA de alpaca. La cuantificación de la expresión relativa mediante normalización con ARNm del gen GAPDH y los cálculos de la expresión relativa se realizaron utilizando el método Ct comparativo (2-ΔΔCt). Se comprobó que la administración de antígenos de Clostridium perfringens más ATRA ejerce un efecto inmunomodulador positivo sobre la IgA en mucosa intestinal de crías de alpacas tratadas con respecto a las no tratadas. Los animales tratados de 1 día de edad y entre 7 a 14 días de edad presentaron mayor producción de ARNm de IgA con respecto a sus sendos grupos no tratados, evidenciando diferencias significativas (p<0.05).Tesi

Rainfall timing and runoff: The influence of the criterion for rain event separation

Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT) is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T0) and three descriptive variables of rain. Our results show that the optimum MIT is 1 hour, which seems to be the minimum period of time required for water in larger macropores to drain and sufficiently modify the effect of antecedent soil moisture on the runoff generation process. Rain events are classified into three significantly different groups: (1) large and intense rains, (2) light rains on wet soil, and (3) light rains on dry soil. Intense rains produce most of the runoff, but there were significant differences between small events in the runoff generated. Of rain events, 63.75% are single-tip events, and many could be dew

Runoff and soil loss in biocrusts and physical crusts from the Tabernas Desert (southeast Spain) according to rainfall intensity

Biological soil crusts (biocrusts) influence hydrological and erosive processes in drylands, and their effects increase with hypothetic successional development. Runoff and raindrops, both dependent on rain intensity, are among the main causes of erosion in these areas. However, little is known about the existence of soil loss nonlinearity in relation to rain intensity and crust types; this nonlinearity could control biocrust succession and dynamics. The assumption of biocrust types as successional stages, which allow space-for-time sampling, makes it advisable to include all the successional stages when exploring possible nonlinearity. We considered seven types of crusts, three physical and four biological. We created four rainfall intensity levels in controlled laboratory conditions: 18, 60, 120, and 240 mm/h. In all but the last, we conducted the experiments at two levels of antecedent soil moisture. Generalized Lineal Models enabled us to test for differences. These analyses confirmed previous knowledge regarding the significant effect of rainfall intensity, crust type and antecedent soil moisture and their interactions on runoff and soil loss, despite the small sample size of the sample units. For example, runoff, and particularly soil loss, decreased along succession. Moreover, some results were novel: the runoff coefficient increased only up to 120 mm/h of rain intensity. A decoupling between runoff and soil loss occurred at high intensities. Soil loss increased as rainfall intensity increased only up to 60 mm/h, and then it decreased, mainly due to physical crusts, because of the formation of a water sheet on the surface due to the incoming rainwater exceeding the drainage capacity. Although soil loss was greater in the incipient cyanobacteria than in the most developed lichen biocrust (Lepraria community), the protection provided by any biocrust against soil loss was great compared to the physical crust, and almost as strong at all rain intensities. Soil loss increased with antecedent soil moisture only in physical crusts. Biocrusts resisted the rain splash even at a rainfall intensity of 240 mm/h

Estación Experimental "El Cautivo" (Desierto de Tabernas, Almería)

En: La Red de Estaciones Experimentales de Seguimiento y Evaluación de la Desertificación (RESEL) . Actividades y Resultados 1995-2004. Dirección General para la Biodiversidad, Ministerio de Medio Ambiente, MadridEl Área Experimental El Cautivo es una instalación permanente, mantenida y gestionada por el Departamento de Desertificación y Geoecología de la Estación Experimental de Zonas Aridas (EEZA) del CSIC, en Almería. El Cautivo inició su andadura en 1990 en el marco del proyecto “Erosión por acarcavamiento en medio semiárido: causas, evolución y restauración” (del Plan Nacional de Ciencia y Tecnología), y ha funcionado sin interrupción desde entonces asociada a otros proyectos de investigación. El Cautivo se escogió por ser una de las áreas del desierto de Tabernas en donde los procesos geomorfológicos parecen ser especialmente activos, enmarcados por el clima más árido de Europa que le confieren características geoecológicas muy especiales. Además, las áreas intensamente acarcavadas, conocidas como malpaís o badlands en inglés, son consideradas como laboratorios naturales que ofrecen en miniatura y en intervalos de tiempo cortos muchas de las formas y procesos erosivos de los paisajes fluviales.El trabajo presentado en este capítulo ha sido financiado total o parcialmente por los siguientes proyectos de investigación: 1) Erosión por acarcavamiento en medio semiárido: causas, evolución y restauración (NAT89-1072-C06-02), 2) DESERMA (AMB93-0844-C06-01), 3-4-5) MEDALUS I, II y III (EPOC-CT90-0014-SMA; EV5V-0128; ENV4-CT95-0118), 6) PROHIDRADE (AMB95-0986-C02-01), 7) EPOHIDRO (HID98-1056-C02-01), 8) PROHISEM (REN2001-2268-C02-01/HID), 9) GEORANGE (CE EVK2-2000-22089, CSIC ENVIR/992/0630), 10) ECONEXUS (REN2000-1513 GLO) y 11) PECOS (REN2003 - 04570/ GLO).Peer reviewe

O ATUAL CENÁRIO DA RELAÇÃO TRABALHADOR-ORGANIZAÇÃO-TRABALHO E OS RISCOS À SAÚDE DO TRABALHADOR

Nesta entrevista à Revista Laborativa, o Professor Dr. Mário Lázaro Camargo, responde a perguntas sobre sua trajetória profissional e trabalhos realizados na área da Psicologia Organizacional e do Trabalho. Discorre ainda sobre o cenário atual no mundo do trabalho, suas implicações à saúde do trabalhador e os desafios neste campo de atuação, para psicólogos e organizações empregadoras. Outro tema abordado por nosso entrevistado é o presenteísmo, um importante fenômeno organizacional da atualidade, e suas consequências na relação ser humano-trabalho-organização

Defining minimum runoff length allows for discriminating biocrusts and rainfall events

The runoff coefficient (RC) is widely used despite requiring to know the effective contributing area, which cannot be known a priori. In a previous work, we defined runoff length (RL), which is difficult to measure. This work aimed to define the minimum RL (mRL), a quantitative and easy proxy of RL, for use in a pilot study on biocrusts in the Tabernas Desert, Spain. We show that RC decreases according to a hyperbola when the contributing area increases, the independent variable being the length of the effective contributing area and its coefficient involving the effects of rainfall and surface features and antecedent conditions. We defined the mRL as the length of the effective contributing area making RC = 1, which is calculated regardless of the area. We studied mRL from three biocrust types and 1411 events clustered in seven categories. The mRL increased with rain volume and intensity, catchment area and slope, whereas plant cover and biocrust succession (with one exception) had a negative effect. Depending on the plot, mRL reached up 3.3-4.0 m on cyanobacterial biocrust, 2.2-7.5 m on the most widespread lichens, and 1.0-1.5 m on late-successional lichens. We discuss the relationships of mRL with other runoff-related parameters

Modelos para estimación de curvas de potencia de referencia aplicadas al análisis del rendimiento de aerogeneradores

El análisis del rendimiento de las curvas de potencia de aerogeneradores requiere un filtrado y caracterización de las mismas. Este filtrado identifica aquellos valores de la curva de potencia en los que la producción es inferior a la esperada, permitiendo analizar el rendimiento y la definición de una curva media que la caracteriza. Los métodos estáticos de filtrado y caracterización actuales presentan, en general, limitaciones en cuanto a su adaptación al comportamiento real del aerogenerador analizado para las condiciones de trabajo existentes. Requieren de la intervención de un técnico cualificado que los supervise, lo que incluye un factor de subjetividad importante y además imposibilita la aplicación de dichos métodos de trabajo en una aplicación informática autónoma. El análisis de los métodos de trabajo actuales, de sus carencias y de los requisitos necesarios para su automatización, dan lugar a nuevos métodos dinámicos de filtrado. Estos nuevos métodos de filtrado deben ser eficientes y permitir un compromiso razonable entre los resultados obtenidos manualmente y los de los algoritmos que puedan automatizar el proceso de cálculo. Los métodos dinámicos de filtrado y caracterización de curvas de potencia permiten su adaptación al comportamiento real del aerogenerador para las condiciones de trabajo existentes. En ellos previamente se analiza un modelo que morfológicamente permite caracterizar a una curva de potencia de un aerogenerador (En este caso, Distribución Normal Acumulada de Gauss). A continuación se define la ecuación correspondiente a dicho modelo y se optimizan los parámetros que la definen con el fin de ajustar el modelo al comportamiento concreto de la máquina y periodo analizados. A continuación se definen los umbrales de filtrado de la curva de referencia y se estima el Rendimiento de la máquina, (función de mérito utilizada, muy sensible a la calidad del filtrado). Se comparan las estimaciones de la función de mérito para cada método comparándolo con un óptimo, el tratamiento manual de los datos por un técnico cualificado. Finalmente, se evalúan las desviaciones de cada método respecto al óptimo y analizan las ventajas e inconvenientes de cada uno. Con esto, se define un método de estimación del rendimiento de aerogeneradores que alcanza un equilibrio entre calidad, recursos necesarios y posibilidades de automatización del proces