Vegetación dispersa y flujos de vertiente en clima semiárido

[Resumen] Se revisa la información disponible sobre la generación y dinámica de los mosaicos de vegetación-suelo desnudo en clima semiárido y su relación con los flujos de vertiente. Muchos de los datos utilizados se obtuvieron en el área experimental de Rambla Honda (Almería) que opera en el marco del proyecto MEDALUS de la Comisión de las Comunidades Europeas. Las conclusiones indican que la diferenciación de las propiedades del suelo entre las fases veegtadas y desnudas se refuerza con el tiempo. Las primeras se convierten en "islas de fertilidad" y núcleos activos de sucesión, mientras que las segundas sufren una progresiva degradación. Los rodales de vegetación obtienen agua de las áreas desnudas adyacentes, de manera que ambas constituyen unidades funcionales, cuya forma y distribución espacial resulta de interacciones entre el crecimiento de las plantas y los flujos de escorrentía y sedimentos a lo largo de las vertientes.[Abstract] A review is made on the available information about the origin and dynamics of vegetation-bare soil mosaics in semi-arid climate and their relation with runoff and sediment fluxes. Data come mostly from the Rambla Honda field site which is being operated under the Medalus project from the Commission of European Communities. Main conclusions show that differences in the soil properties between vegetated and bare patches are self-reinforced with time. The former become "fertility islands" and active successional spots, while the latter suffer a progressive degradation. Vegetated patches obtaln water from neighbour bare areas so that both become functional units. Shapes and spatial patterns of such units result from interactions between plant growth and downhill fluxes of water and sediments

A neuro-scientific approach to enviroment care

Grass-root feedback to public agencies’ policies for coping with global change threats is poor and reactive. Concurrently, human population becomes more urban, isolated from nature and unable to take personal decisions about it. Therefore, helping societal involvement and proactive behavior towards nature is a crucial challenge nowadays. This paper intends to explore the role of emotions in support of a positive interaction in human/ environment systems, to assess their evolutionary changes and ways to eventually readdress its trend. For that purpose, the latest neuroscientific findings are applied to disentangle the nature impact on the human emotional system by comparing the present people’s attitudes to those from pre-agrarian cultures. This knowledge allows drawing guidelines to improve people´s concern to care for the environment.La retroalimentación “grass-root” para las políticas de los organismos públicos que tienen como objetivo enfrentarse a las amenazas del cambio global es pobre y reactiva. Al mismo tiempo, la población humana se vuelve más urbana, aislada de la naturaleza e incapaz de tomar decisiones personales al respecto. Por lo tanto, ayudar a la participación social y al comportamiento proactivo hacia la naturaleza es en la actualidad un desafío crucial. Este artículo intenta explorar el papel de las emociones en apoyo de una interacción positiva entre los sistemas humanos/ambientales, con el objeto de evaluar sus cambios evolutivos y caminar finalmente hacia una reorientación de su tendencia. Con este propósito, se aplican las últimas conclusiones neurocientíficas para desentrañar el impacto de la naturaleza en el sistema emocional humano, comparando las actitudes de las personas actuales con las de las culturas preagrarias. Este conocimiento permite diseñar pautas que mejoren la preocupación de las personas por el cuidado del medio ambiente

Variaciones sedimentarias durante el Eoceno medio en la sierra de Andía (Navarra)

In this paper, tkie stratigraphical and lithological character- istics of the Middle Eocene are established, in the Sierra de Andia (Navarra, Spain). Examples of the cross-stratification are described and the directional data analyzed. A study of the basin evolution is elaborated. It is pro- posed a correlation with the youngest sediments of the Sierra de Urbasa, situated more to the West

Comparison of Three Operative Models for Estimating the Surface Water Deficit Using ASTER Reflective and Thermal Data

24 pages, 4 figures, 4 tables.-- Special Issue "Remote Sensing of Natural Resources and the Environment".Three operative models with minimum input data requirements for estimating the partition of available surface energy into sensible and latent heat flux using ASTER data have been evaluated in a semiarid area in SE Spain. The non-evaporative fraction (NEF) is proposed as an indicator of the surface water deficit. The best results were achieved with NEF estimated using the "Simplified relationship" for unstable conditions (NEF_Seguin) and with the S-SEBI (Simplified Surface Energy Balance Index) model corrected for atmospheric conditions (NEF_S-SEBIt,) which both produced equivalent results. However, results with a third model, NEF_Carlson, that estimates the exchange coefficient for sensible heat transfer from NDVI, were unrealistic for sites with scarce vegetation cover. These results are very promising for an operative monitoring of the surface water deficit, as validation with field data shows reasonable errors, within those reported in the literature (RMSE were 0.18 and 0.11 for the NEF, and 29.12 Wm-2 and 25.97 Wm-2 for sensible heat flux, with the Seguin and S-SEBIt models, respectively).This study received financial support from several different research projects: the integrated EU project, DeSurvey (A Surveillance System for Assessing and Monitoring of Desertification) (ref.: FP6- 00.950, Contract nº. 003950), the PROBASE (ref.: CGL2006-11619/HID) and CANOA (ref.: CGL2004-04919-C02-01/HID) projects funded by the Spanish Ministry of Education and Science; and the BACAEMA ('Balance de carbono y de agua en ecosistemas de matorral mediterráneo en Andalucía: Efecto del cambio climático', RNM-332) and CAMBIO ('Efectos del cambio global sobre la biodiversidad y el funcionamiento ecosistémico mediante la identificación de áreas sensibles y de referencia en el SE ibérico', RNM 1280) projects funded by the Junta de Andalucía (Andalusian Regional Government).Peer reviewe

Geomorphic Processes above Timberline in the Spanish Pyrenees

14 páginasPeer reviewe

A 1973-2008 archive of climate surfaces for NW Maghreb

Climate archives are time series. They are used to assess temporal trends of a climate-dependent target variable, and to make climate atlases. A high-resolution gridded dataset with 1728 layers of monthly mean maximum, mean and mean minimum temperatures and precipitation for the NW Maghreb (28ºN-37.3ºN, 12ºW-12ºE, 1-km resolution) from 1973 through 2008 is presented. The surfaces were spatially interpolated by ANUSPLIN, a thin-plate smoothing spline technique approved by the World Meteorological Organization (WMO), from georeferenced climate records drawn from the Global Surface Summary of the Day (GSOD) and the Global Historical Climatology Network-Monthly (GHCN-Monthly version 3) products. Absolute errors for surface temperatures are approximately 0.5ºC for mean and mean minimum temperatures, and peak up to 1.76ºC for mean maximum temperatures in summer months. For precipitation, the mean absolute error ranged from 1.2 to 2.5 mm, but very low summer precipitation caused relative errors of up to 40% in July. The archive successfully captures climate variations associated with large to medium geographic gradients. This includes the main aridity gradient which increases in the S and SE, as well as its breaking points, marked by the Atlas mountain range. It also conveys topographic effects linked to kilometric relief mesoforms.Focus on Morocco, Algeria and Tunisia North of 28ºNDeSurvey IP (European Commission FP6 contract No. 003950), MesoTopos (Junta de Andalucia PE P08-RNM-04023) and MELODIES (European Commission FP7, contract No. 603525)Ye

Analysis of effective resistance calculation methods and their effect on modelling evapotranspiration in two different patches of vegetation in semi-arid SE Spain

International audienceEffective parameters are of major importance in modelling surface fluxes at different scales of spatial heterogeneity. Different ways to obtain these effective parameters for their use in meso-scale and GCM models have been studied. This paper deals with patch-scale heterogeneity, where effective resistances were calculated in two patches with different vegetation (Retama sphaerocarpa (L.) Boiss shrubs, and herbaceous plants) using different methods: aggregating soil and plant resistances in parallel, in series or by an average of both. Effective aerodynamic resistance was also calculated directly from patch fluxes. To assess the validity of the different methods used, the Penman-Monteith equation was used with effective resistances to estimate the total ?E for each patch. The ?E estimates found for each patch were compared to Eddy Covariance system measurements. Results showed that for effective surface resistances, parallel aggregation of soil and plant resistances led to ?E estimates closer to the measured ?E in both patches (differences of around 10%). Results for effective aerodynamic resistances differed depending on the patch considered and the method used to calculate them. The use of effective aerodynamic resistances calculated from fluxes provided less accurate estimates of ?E compared to the measured values, than the use of effective aerodynamic resistances aggregated from soil and plant resistances. The results reported in this paper show that the best way of aggregating soil and plant resistances depends on the type of resistance, and the type of vegetation in the patch

Analysis of effective resistance calculation methods and their effect on modelling evapotranspiration in two different patches of vegetation in semi-arid SE Spain

Effective parameters are of major importance in modelling surface fluxes at different scales of spatial heterogeneity. Different ways to obtain these effective parameters for their use in meso-scale and GCM models have been studied. This paper deals with patch-scale heterogeneity, where effective resistances were calculated in two patches with different vegetation (Retama sphaerocarpa (L.) Boiss shrubs, and herbaceous plants) using different methods: aggregating soil and plant resistances in parallel, in series or by an average of both. Effective aerodynamic resistance was also calculated directly from patch fluxes. To assess the validity of the different methods used, the Penman-Monteith equation was used with effective resistances to estimate the total λE for each patch. The λE estimates found for each patch were compared to Eddy Covariance system measurements. Results showed that for effective surface resistances, parallel aggregation of soil and plant resistances led to λE estimates closer to the measured λE in both patches (differences of around 10%). Results for effective aerodynamic resistances differed depending on the patch considered and the method used to calculate them. The use of effective aerodynamic resistances calculated from fluxes provided less accurate estimates of λE compared to the measured values, than the use of effective aerodynamic resistances aggregated from soil and plant resistances. The results reported in this paper show that the best way of aggregating soil and plant resistances depends on the type of resistance, and the type of vegetation in the patch.This work received financial support from several different research projects: the PROBASE (ref.: CGL2006-11619/HID) and CANOA (ref.: CGL2004-04919-C02-01/HID) projects funded by the Spanish Ministry of Education and Science; and the BACAEMA (“Balance de carbono y de agua en ecosistemas de matorral mediterráneo en Andalucía: Efecto del cambio climático”, RNM-332) and CAMBIO (“Efectos del cambio global sobre la biodiversidad y el funcionamiento ecosistémico mediante la identificación de áreas sensibles y de referencia en el SE ibérico”, RNM 1280) projects funded by the regional government Junta de Andalucía. The first author enjoyed a pre-doctoral grant from the Spanish Ministry of Science and Technology

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

Land degradation means a loss of management options

This essay approaches land degradation by targeting its ultimate thermodynamic causes, rather than its immediate environmental consequences. The objective is to make some propositions that could help understand the essence of the process, and contribute to a theoretical framework to be developed. These propositions are: 1. Human populations are an ecosystem component, not an external driver. 2. Coupled Human and Natural Systems (CHANS) tend to increase their overall complexity over time. CHANS complexity cannot feasibly be managed. 3. CHANS are made up of two types of subsystems, a consuming Foreland (FL) consisting of the human population, and a producing Backland (BL) in its environment. 4. The FL maintains its order at the expense of simplifying the BL, which becomes an entropy sink. This is the essence of ecological degradation, which is inherent to CHANS persistence. 5. Land degradation is an ecological state, not a landscape type. Hence it should be assessed within a complete range of states of ecological maturity. 6. Land use creates degradation proportional to the simplification of the ecosystems involved. Such degradation can be defined as a decrease in exergy, and results in loss of management options. Three associated corollaries are: a) A more effective target may be to regulate rather than attempt to eliminate land degradation; b) Monitoring ecological degradation trajectories may be more effective than assessing land degradation states; c) Land degradation can be decreased by maximizing the potential for interconversion between land uses.This work was supported by the European Commission under the DeSurvey IP [FP6 Integrated Project contract no. 003950], the European Space Agency under the DesertWatch Extension project [DUE contract no. 18487/04/I-LG] and Tragsatec (Grupo Tragsa) [contract no. 25.604]