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Most studies on the geomorphological evolution of the Holocene from the Ebro depression (NE Spain) are focused on the period up to the Roman Epoch (218 BC–476 AD) while some references to medieval (476 AD–15th century) deposits are also occasionally dated. This paper focuses on the establishment of aggradation units on the valley bottoms and slopes of the Ebro depression after 1400 BP, their origin, comparison with other areas, and relationship with global paleoenvironmental changes. These units were produced after the incision phase that marked the end of the large Holocene accumulation (unit H1) around 1400 BP (at the end of the Late Roman Epoch). Morphosedimentary records enable us to establish three aggradation units during the last 1400 years: unit H2 ( ca. 1400–650 cal BP); unit H3 – with two H3A subunits ( ca. 650–500 cal BP) and H3B ( ca. 500–320 cal BP); and the H4 unit (after 320 cal BP). These units are organized following five types of aggradation/incision arrangements with differing complexities. There are also connections among these units and two slope stages in the region. Finally, the genetic relationships between these units and global paleoenvironmental changes are shown (LALIA, MCA, and LIA) and related to anthropic activity. This contribution is the first detailed and systematic approach to the study of morphosedimentary units and sedimentary arrangements during the Recent Holocene in the Mediterranean area.

The lower Gállego River has been strongly degraded since the 1960s due to human activity (gravel mining, dump accumulation, channeling works), which has produced a deep channel incision. Although these human-driven processes are usually reported in fluvial bibliography, in this case, more complex results are observable. For instance, regarding the depth and incision rates, we observed no relationship between the most anthropically impacted areas and the sections with the deepest incisions; moreover, the deepening process continues 40 years after the human interventions ceased. The reason for this maladjustment is the role played by the exhumation of the underlying Pleistocene substrate, affected by the synsedimentary processes of karstification. The appearance of paleodolines filled with fine sediments on the incision bottom and sides is the main factor conditioning the continuity and magnitude of the process. Besides, these paleodepressions direct the river dynamics and course, thus favoring its widening when they appear and causing the development of a new riverbed (Qt13) while the 1960s floodplain (Qt12) is becoming an old terrace located between 5 and 11 m above the new alluvial bottom. There are no previous records about this kind of consequences in the regional fluvial dynamics. El curso bajo del río Gállego ha sido fuertemente degradado desde los años 1960 por la actividad antrópica (extracción de áridos, acumulaciones de escombros, obras de encauzamiento) que ha conducido a una fuerte incisión. Aunque este tipo de procesos inducidos por el hombre son habituales en la bibliografía fluvial, en este caso se aprecian efectos más complejos. Son, por ejemplo, la profundidad y velocidad de la incisión, la falta de relación entre puntos de máxima intervención y los de mayor incisión o la continuidad del proceso cuarenta años después de cesar ese tipo de acciones. La respuesta a estos desajustes está en el papel que está jugando la exhumación del sustrato pleistoceno infrayacente, afectado por procesos sin sedimentarios de karstificación. La aparición de paleodolinas rellenas de sedimentos finos en el fondo y laterales de la incisión es actualmente el principal determinante de su importancia y continuidad. Además, estas paleodepresiones dirigen la dinámica y trazado del río y puntualmente fa- vorecen ensanchamientos laterales. Esto propicia la aparición de un nuevo lecho (Qt13) a medida que el lecho de los años 1960 (Qt12) va quedando como una terraza colgada entre 5 y 11 m sobre el nuevo fondo aluvial. No hay antecedentes de este tipo de consecuencias en la dinámica fluvial regional. Fil: Peña Monné, Jose Luis. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Longares Aladrén, Luis Alberto. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Rubio Fernández, V.. Universidad Autónoma de Madrid; España Fil: Sampietro Vattuone, Maria Marta. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Geoarqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina Fil: Sánchez-Fabre, Miguel. Universidad de Zaragoza. Facultad de Filosofía y Letras; España

Triggered by frequent high temperatures and scarce precipitation, droughts are a recurrent phenomenon in the Mediterranean Basin, causing significant impacts on forests. We analyzed the effects of drought intensity, duration, and seasonality on tree growth by investigating the relationship between the Standardized Precipitation-Evapotranspiration Index (SPEI) at different time scales and tree-ring width (TRW) in three pine species (Pinus halepensis Mill., P. sylvestris L, and P. uncinata Ramond ex A.DC) throughout a dense dendrochronological network in the Mediterranean Basin. We used generalized linear mixed models to predict such values over the entire distribution of the analyzed species. Furthermore, in areas where the species coexist, we analyzed the same parameters to highlight differences in their responses to similar climatic conditions. Our results showed that the maximum intensity of drought-affected conifers occurred more in the southern areas of the Spanish Mediterranean coast, especially P. halepensis, with maximum values of r = 0.67, while in the rest of the study area, the intensity decreased with elevation; we obtained maximum values of r = 0.40 and r = 0.33 for P. sylvestris and P. uncinata, respectively. This spatial distribution was also related to the duration of the drought impacts, showing that areas with lower intensity had shorter durations (2–4 months). We observed a latitudinal pattern in the seasonality of the drought impacts, with earlier growing seasons at high elevations (June–August) and later ones in the semi-arid Mediterranean. Similar intensity impacts were found in P. halepensis and P. sylvestris coexistence zones, although P. halepensis had a much longer duration and an earlier beginning of seasonality. Higher intensity, duration, and seasonality of drought effects were observed for P. sylvestris in areas where P. sylvestris and P. uncinata are distributed sympatrically. Understanding the plasticity and climatic response of these common southern European species to different types of droughts is crucial in the context of climate change where droughts are increasing in frequency and intensity.

Understanding the influence of the current climate on the distribution, composition, and carbon storage capacity of Mediterranean tree species is key to determining future pathways under a warmer and drier climate scenario. Here, we evaluated the influence of biotic and environmental factors on earlywood (EW) and latewood (LW) growth in Aleppo pine (Pinus halepensis Mill.). Our investigation was based on a dense dendrochronological network (71 sites), which covered the entire distribution area of the species in the Iberian Peninsula (around 119.652 km2), and a high-resolution climate dataset of the Western Mediterranean area. We used generalized linear-mixed models to determine the spatial and temporal variations of EW and LW across the species distribution. Our results showed an intense but differentiated climatic influence on both EW and LW growth components. The climatic influence explained significant variations across the environmental gradients in the study area, which suggested an important adaptation through phenotypic plasticity and local adaptation to varying climatic conditions. In addition, we detected a clear spatial trade-off between efficiency and safety strategy in the growth patterns across the species distribution. Additionally, in more productive areas, the trees presented a higher proportion of EW (more efficient to water transport), while, in more xeric conditions, the LW proportion increased (more safety to avoid embolisms), implying an adaptation to more frequent drought episodes and a higher capacity of carbon depletion. We therefore concluded that Mediterranean forests adapted to dryer conditions might be more efficient as carbon reservoirs than forests growing in wetter areas. Finally, we advocated for the need to consider wood density (EW/LW proportion) when modeling current and future forest carbon sequestrations.

18 Pags.- 8 Figs.- 2 Tabls. The definitive version is available at: https://www.sciencedirect.com/science/journal/11257865, Understanding the regional hydroclimatic variability beyond the instrumental period is essential to contextualize the current climatic period within a longer record. Dendrochronology has been used as a powerful tool for estimating the temperature and precipitation variability of the last centuries on an annual and even seasonal scale. However, most of the centenary trees in Spain are located in high-elevation mountain environments, so the reconstructed signal is not representative of the climate variability of the lowlands, where the main cities and most of the population and human activities are located. Here we present a precipitation reconstruction of the Bardenas Natural Park, a semi-arid environment within the Ebro Valley, based on 61 new tree-ring width series of Pinus halepensis Mill. The new chronology, calibrated against high-resolution instrumental precipitation data, uncovers a high and robust relationship with the annual precipitation (from previous June to current May) (1951−2012 CE; r = 0.78;), representing the precipitation totals of the hydrological year. Our reconstruction explains 61 % of the annual precipitation for the period 1951−2012 and is representative of the lowlands of the Northeast of Spain. We identified 12 extremely dry and 11 extremely wet years, finding the first half of the 20th century to be the period with most extreme episodes of the reconstruction. Additionally, we found a strong agreement between our tree-ring based reconstruction and the lowlands documentary-based drought estimators (rogation ceremonies). These findings contribute to improving our understanding of past hydroclimatic variability in semi-arid lowland areas where available proxy records are rare., ET was partially supported by the National Science Foundation (grant numbers OISE-1743738AGS-1702439). RSN is funded by a “Juan de la Cierva” postdoctoral grantFJCI-2017-31595. ET, RSN, MAS, LAL, MDL, and JMC are partially supported by the Government of Aragón through the “Program of research groups” (group H38, “Clima, Agua, Cambio Global y Sistemas Naturales”). MDL, JMC, MAS, and LAL were partially supported by the Spanish Ministerio de Economía y Competitividad (grant no. CGL2015-69985- R). KN is supported by contract no. C3330-19-952011 for co-financing the operation of the “Researchers-2.1-UL-BF-952011” by the Ministry Education, Science and Sport of the Republic of Slovenia and.

International audience; Please cite this article as: Alcolea, M., Dufraisse, A., Royo, Marí., Mazo, C., de Luis, Martí., Longares, L.A., Utrilla, P., Fábregas, Ramó., Dendro-anthracological tools applied to Scots type pine forests exploitation as fuel during the Mesolithic-Neolithic transition in the southern central pre-Pyrenees (Spain), Quaternary International (2020), https://doi.org/10.1016/j.quaint.2020.10.029This work focuses on the reconstruction of fuelwood procurement during the Mesolithic-Neolithic transition in the southern central Pre-Pyrenees (Spain). The study combines wood charcoal identification with the application of dendro-anthracological approaches in the archaeological sequence of Esplugón (9.4-6.8 kyr cal BP) (Sabiñanigo, Huesca). Scots type pine (Pinus sylvestris tp.) reaches in this record around 90% of exploited firewood in line with its abundance in the inner Iberia mountainous areas during the onset of the Holocene. The classification of pine wood fragments in anthraco-groups is based on the combination of different dendroanthracological tools: i) pith location tool and wood diameter estimation based on the trigonomethric method tool (ADmodel), ii) the study of growth rate based on the annual tree-ring width measurements, and iii) a modern dendrological dataset. There are hardly any differences observed in firewood procurement between the last hunter gatherers and the first farmers in the long sequences from rock-shelters with recurrent human occupations. First results from this site point to the exploitation of whole trees but a high use of small pine branches probably from the gathering of branch shedding.

The Visigothic and Paleo Islamic settlement system in the Ebro Valley (NE Spain) is yet not well known. This is due to the lack of research and low visibility of the settlements, but not to an effective demographic recession. In this paper we present the results of our research in Los Pedregales archaeological site, in Huesca Province. The site appears as a complex assemblage of archaeological artifacts from different chronologies (Roman, Early Middle Ages, Modern…) and numerous stone structures in a severely eroded terrain. Within the framework of a geoarchaeological research, we carried out an intensive surface survey and the excavation of some of the structures. Thus, we interpret the main phase of the site as an assemblage of storage pits dated between the 6th and the 9th Centuries AD. This is new data for the improvement of our understanding of past rural landscapes and the scattered peasant communities that dwelled in them. In this paper, we describe and interpret the studied structures, we study the most relevant artifacts recovered —mainly pottery— and we set the site in the context of the general settlement system and historical processes that affect this territory., El conocimiento de la ocupación visigoda y paleoislámica en el valle del Ebro resulta un tanto difuso, más por falta de investigaciones y por la escasa visibilidad de los asentamientos, que por un efectivo despoblamiento. En este artículo presentamos los resultados de nuestras investigaciones en el yacimiento de Los Pedregales, en la provincia de Huesca, un sas cronologías (romanos, altomedievales, modernos…) junto con numerosas estructuras pétreas en un área completamente alterada por procesos erosivos. Una minuciosa prospección y la excavación de algunas estructuras en el marco de un estudio geoarqueológico, nos ha permitido explicar la ocupación principal del yacimiento como un campo de silos datado entre los siglos vi y ix, que aporta una nueva referencia para la comprensión de los paisajes rurales antiguos y las comunidades campesinas dispersas que los ocupan. En el artículo se describen e interpretan las estructuras, se estudian los materiales más relevantes, especialmente los cerámicos, y se contextualiza el yacimiento con relación al poblamiento y los procesos históricos que afectan a este territorio.

On two accumulation levels, separated by an unevenness up to 2 m, two contrasted plant communities can be differentiated in subalpine stage of the Pyrenees: the dense tussock-forming grass Nardus stricta, at the upper level (L1), and the open chalk grasslands at the lower level (L2). In order to confirm the soil-relief-grasslands relationships, we analyzed and compared soil pedogenesis and properties in both accumulation levels. In addition, we classify the soils following WRB and ST systems and we discuss the finesse of both taxonomies in these high mountain environments. The work has been carried out at 1900 masl, in the Ordesa and Monte Perdido National Park (PNOMP), in the summer grasslands site of La Estiva (Fanlo, Central Pyrenees, NE Spain). Five soil pits were studied in every accumulation level (L1 and L2) for a side-by-side comparison. The study of soils in the two levels of accumulation reveals a series of differences in their genesis, properties and soil classification. The accumulation of organic matter and lixiviation are the dominant edafogenetic processes in L1, to which we must add the rejuvenation by gully erosion in L2. Soils at L1 and L2 shared many physical properties as a fine granulometry, with a homogeneous particle-size distribution with depth. In both levels, the soils lack carbonates, even though limestones are the parental material. The soils in L1 have a greater thickness and, thus, a higher water holding capacity than in L2. In relation to chemical properties, soils in L1 have a significantly lower pH, a lower base saturation, and lower available calcium content than in L2, reflecting a more intense leaching process, consistent with a longer period of slope stability. Over L1 with Nardus mat-grasslands, the main soil is classified as Orthoeutric Cambisols (Clayic, Humic), and the soil over L2, with chalk-grasslands, as Hypereutric Leptosols (Loamic, Ochric). Soil taxonomy System (USDA), giving more weight to the temperature regime, classify both soils as Haplocryept, at the level of great group, separating them at the subgroup level as Typic Haplocryept (L1) and Lithic Haplocryept (L2), according to the depth at which limestone appears (lithic contact). Definitely, the microtopograhy and geomorphologic context, is linked to the pedodiversity, which goes hand in hand with plant diversity in this subalpine environment.

Flat-bottomed valleys formed by Holocene fills are the most characteristic landforms in the center of the Ebro basin. This paper analyzes, within a regional framework, a small fluvial basin located in the north of the Alcubierre Range. Three Holocene morphosedimentary units (H1-H3) and a subfunctional level (H4) are identified. These units are representative of the regional geomorphological evolutionary process in the Ebro basin. New chronological insights on climate and landscape management are provided by a study of the Bastarás weir, a construction made for water flow management during the Little Ice Age (LIA). The integration of Val de Zaragoza radiocarbon datings intothe regional framework enables the authors to identify the main formation stages, as well as the influence of climatic and human factors on its evolution. The intensification of human pressure in the territory is reflected in a progressive increase in sediment accumulation rates in the valleys, peaking during Roman times and the Little Ice Age. Los valles de fondo plano formados por rellenos holocenos constituyen los paisajes más característicos del sector central de la cuenca del Ebro. En este trabajo se analiza una pequeña cuenca fluvial localizada en el norte de la Sierra de Alcubierre, en la que se han identificado tres unidades morfosedimentarias holocenas (H1-H3) y un nivel subfuncional (H4), que son representativos de la evolución geomorfológica regional de la Cuenca del Ebro. Uno de los aspectos más relevantes del valle lo constituye el azud de Bastarás, construcción realizada durante la Pequeña Edad del Hielo para el aprovechamiento del agua, que aporta nuevos datos cronológicos sobre dicha época y acerca de la gestión del territorio. La integración de las dataciones radiocarbónicas obtenidas en la Val de Zaragoza en un marco regional ha permitido precisar las principales etapas de formación de los valles de fondo plano, así como la importancia de los factores climáticos y humanos en su evolución. La intensificación de la presión humana sobre el territorio queda reflejada en un progresivo aumento en las tasas de acumulación de sedimentos en los valles, alcanzando sus picos máximos en Época Romana y en la Pequeña Edad del Hielo. Fil: Peña Monné, José Luis. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Sampietro Vattuone, Maria Marta. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Geoarqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina Fil: Longares Aladrén, Luis A. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Pérez Lambán, Fernando. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Sánchez Fabre, Miguel. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Alcolea García, M.. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Vallés, L.. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Echeverría Arnedo, M. T.. Universidad de Zaragoza. Facultad de Filosofía y Letras; España Fil: Baraza, C.. Universidad de Zaragoza. Facultad de Filosofía y Letras; España

An analysis of the spatial and temporal variability of daily precipitation concentration (CI) in Spain was made based on a high‐resolution (5 × 5 km) daily gridded precipitation data set for the 1950–2012 period. For each grid point in the Iberian Peninsula (IP) and Balearic and Canary Islands, the average annual CI was computed, as well as its coefficient of variation and the 5th and 95th percentiles. Annual values were also computed, and the time series of the index were used to assess temporal trends over the whole period. The spatial distribution of the CI showed a strong relationship with the orographic barriers near the coastlines. The Canary Islands showed the highest values of CI, along with the eastern Mediterranean facade of the IP. The highest inter‐annual variations of the CI occurred in the southern IP and in the southern Canary Islands. The trends of CI were, overall, positive and significant, which indicates an increase of daily precipitation concentration over the study period and an increasing environmental risks scenario where erosivity, torrentiality, and floods may become more frequent.

12 Pags.- 34Figs.- 3 Tabls., The negative impacts of drought on forest growth and productivity last for several years generating legacies, although the factors that determine why such legacies vary across sites and tree species remain unclear. We used an extensive network of tree‐ring width (RWI, ring‐width index) records of 16 tree species from 567 forests, and high‐resolution climate and normalized difference vegetation index (NDVI) datasets across Spain during the common period 1982‒2008 to test the hypothesis that climate conditions and growth features modulate legacy effects of drought on forests. Legacy effects of drought were calculated as the differences between detrended‐only RWI and NDVI series (i.e. after removing long‐term growth trends) and pre‐whitened RWI and NDVI series predicted by a model including drought intensity. Superposed Epoch Analysis (SEA) was used to estimate whether legacy effects differed from random. Finally, legacy effects were related to water balance, growth persistence and variability, and tree species identity. We found a widespread occurrence of drought legacy effects on both RWI and NDVI, but they were seldom significant. According to SEA, first‐year drought legacies were negative and different from random in 9% and 5% of the RWI and NDVI series respectively. The number of significant second‐ and third‐year legacies was substantially lower. Differences between RWI and NDVI legacies indicate that canopy greenness and radial growth responses to drought are decoupled. We found variations in legacies between tree species with gymnosperms presenting larger first‐year drought legacies than angiosperms, which were exposed to less severe droughts. Greater growth variability can explain the presence of first‐year RWI legacies in gymnosperms from dry sites despite that the relationship between growth variability and legacies was complex. Synthesis. Accounting for species and site responses to drought provides a better understanding of the magnitude and duration of drought legacies on forest growth and productivity. Despite the widespread occurrence of growth reductions in the years during and after drought occurrence, significant legacies were not very common, mostly lasted one year, and were more widespread in gymnosperms. These are relevant factors to be considered in the future when studying the consequences of drought on forest productivity and tree growth., This study was financially supported by: Xunta de Galicia, Grant/Award Number: PGIDIT06PXIB502262PR, GRC GI‐1809; INIA, Grant/Award Number: RTA2006‐00117; CANOPEE, 2014‐2020‐FEDER funds; and Spanish Science Ministry: RTI2018‐096884‐B‐C31, RTI2018‐096884‐B‐C33, AGL2017‐83828‐C2‐2R and ENV4‐CT97‐0641 projects. GSB was supported by a ‘Juan de la Cierva Formación’ grant from MINECO (FJCI 2016‐30121). This research was supported by the BERC 2018‐2021 program, and by the Spanish Ministry of Science, Innovation and Universities through the BC3 María de Maeztu excellence accreditation (MDM‐2017‐0714) and the IBERYCA (CGL2017‐84723‐P) project. R.S.S. was supported by VULBOS project (UPO‐1263216, FEDER Funds, Andalusia Regional Government, Consejería de Economía, Conocimiento, Empresas y Universidad 2014‐2020), and A.H. by PinCaR project (UHU‐1266324, FEDER Funds, Andalusia Regional Government, Consejería de Economía, Conocimiento, Empresas y Universidad 2014‐2020). K.N. was supported by the Ministry of Education, Science and Sports (Republic of Slovenia, Raziskovalci‐2.1‐UL‐BF‐ C3330‐19‐952011).

21 Pags.- 5 Figs.- 1 Appendix. - Suppl. Data., This study links tree-ring growth and gross primary production for a variety of forest types under different environmental conditions across Spain. NOAA-AVHRR satellite imagery data were combined with dendrochronological records and climate data at a fine spatial resolution (1.21 km2) to analyze the interannual variability of tree-ring growth and vegetation activity for different forest biomes from 1981 to 2015. Specifically, we assessed the links between tree-ring width indices (TRWi), the Normalized Difference Vegetation Index (NDVI) and a variety of environmental conditions, represented by climatic variables (air temperature, precipitation, evapotranspiration and water balance) and elevation. The impact of these variables on tree growth was assessed by means of the Predictive Discriminant Analysis (PDA). Results reveal a general positive and significant relationship between inter-annual variability of the NDVI at a high spatial resolution (1.21 km2) and tree-ring growth. Maximum correlations between NDVI and tree-ring growth were recorded when cumulative NDVI values were considered, in some cases covering long time periods (6–10 months), suggesting that tree growth is mainly related to Gross Primary Production (GPP) at annual scale. The relationship between tree-ring growth and inter-annual variability of the NDVI, however, strongly varies between forest types and environmental conditions., This work was supported by the research projects CGL2014-52135-C03-01, CGL2015-69186-C2-1-R, CGL2015-69985-R, CGL2013-48843-C2-1-R, AGL2014-53822-C2-1-R, (BFU2010-21451), PCIN-2015-220, CGL2016-81706-REDT and CGL2017-82216-R financed by the Spanish Commission of Science and Technology and FEDER, 1560/2015: Herramientas de monitorización de la vegetación mediante modelización ecohidrológica en parques continentales financed by the Red de Parques Nacionales, IMDROFLOOD financed by the Water Works 2014 co-funded call of the European Commission, CROSSDRO financed by the AXIS (Assessment of Cross(X) – sectorial climate Impacts and pathways for Sustainable transformation) JPI-Climate co-funded call of the European Commission and INDECIS, which is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462). Financed by the Spanish Commission of Science and Technology and FEDER, and INDECIS, which is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462). Natalia Martin-Hernandez was supported by a doctoral grant by the Aragon Regional Government, Marina Peña-Gallardo was granted by the Spanish Ministry of Economy and Competitiveness and Miquel Tomas-Burguera was supported by a doctoral grant by the Spanish Ministry of Education, Culture and Sport. Raúl Sánchez-Salguero, Antonio Gazol and Gabriel Sangüesa-Barreda were supported by Postdoctoral grants (IJCI-2015-25845, MINECO-FPDI 2013-16600 and FJCI 2016-30121, respectively; FEDER funds). This work also benefited from funding from Xunta de Galicia (PGIDIT06PXIB502262PR, GRC GI-1809, ROCLIGAL-10MDS291009PR), INIA (RTA2006-00117), and Interreg V-A POCTEFA (CANOPEE, 2014-2020-FEDER funds) projects.

13 páginas.- 10 figuras. - 1 tabla.- referencias.- Supplementary data to this article can be found online athttps://doi.org/10.1016/j.scitotenv.2020.139121, The two most widely extended mountain grasslands in Europe (Nardus-mat grasslands and chalk grasslands) are distributed forming complex patterns. In the Ordesa and Monte Perdido National Park (Central Pyrenees, NE-Spain), they grow as secondary pastures within the treeline ecotone at the subalpine belt. This work aims to show the influence of soil properties on the spatial distribution of these pastures, under a dynamic geomorphology. Soils are sampled under both grasslands, which grow on different cumulative levels: Nardus-mat grasslands in the upper level (L1) and chalk grasslands in the lower level (L2). Soils in L1 have a significantly higher acidity, lower soluble ions and exchangeable calcium content than those in L2, reflecting a more intense leaching process, consistent with a longer period of slope stability. Qualitative differences are detected in the soil organic matter of the soil, using carbon and nitrogen isotopes, lighter in L2 soils than in L1 soils, due to a higher proportion of legumes growing in L2 (chalk grasslands). Soils in L1 and L2 shared many physical properties, such as a fine and homogeneous texture in the whole profile (silty clay or silty clay loam), and high aggregate stability and porosity in the topsoil. In contrast, the soils in L2 are shallower than in L1, which reduces their water-holding capacity. The soil is classified as Orthoeutric Cambisol (Clayic, Humic) in L1 but its rejuvenation, by gully erosion, transforms it into an Hypereutric Leptosol (Loamic, Ochric) in L2 (Typic Haplocryept and Lithic Haplocryept, respectively by Soil Taxonomy system). Definitely, the distribution of both grasslands for the studied area is linked to two cumulative levels of different ages, which in turn is strongy related to different soil properties., This study is part of the results of a microproject funded by the “Instituto de Estudios Altoaragoneses-Diputación de Huesca (Call 2018). Lucía Buendía was supported by a novel research contract, funded by the Institute for Research into Environmental Sciences (IUCA) of the University of Zaragoza. This work has been partially financed by the Regional Government of Aragón (Geoforest research group S51_17R) co-financed with FEDER 2014-2020 “Construyendo Europa desde Aragón”. The authors would also like to thank Federico Fillat for his help in the field and for their constructive comments and suggestions, which led to a substantial improvement of the paper.

The scarp of Remolinos-Juslibol is an abrupt relief formed by Miocene gypsums located on the left bank of the Ebro River, in the vicinity of the city of Zaragoza. This work provides data for the reconstruction of the channel morphology and dynamics of the Ebro River and its interaction with the gypsum scarp from the Little Ice Age (LIA) to the present day. At the same time, several scenarios are also proposed for this interaction during the MCA (Medieval Climate Anomaly). To do this, different proxies are used, such as historical maps and records, morphosedimentary records of the tributary ephemeral streams, data from paleofloods, and the evolution of Medieval castles built on the scarp. During the MCA, the river was centered on its floodplain. Large alluvial fans developed by lateral ephemeral streams coming from the north since at least the Chalcolitic-Bronze age continued with their dominant dynamics during the Medieval times. Interaction with the scarp was scarce during this period and this allowed the building of castles on this relief. Later, the Ebro River moved its meanders towards the scarp, eroding most part of the lateral alluvial fans; in addition, infilled valleys were left hanging by the rapid retreat of the scarp and the events of rockfalls and landslides were very active. The map of Dew Rodolphe (1746) and the dating of these events confirm that this erosive process developed mainly during the second part of the LIA (18–19th centuries). From the middle of the 19th century, the fluvial sinuosity of the Ebro River increased and progressively separated from the scarp, which evolved to the present relative stability, in which landslides and rockfalls are scarce.

Annual periodicity of cambium production of xylem and phloem cells has rarely been compared in trees from different environments. We compared the structure of cambium and the youngest xylem and phloem increments in four tree species, Fagus sylvatica, Picea abies, Pinus sylvestris and Pinus halepensis, from nine temperate and Mediterranean sites in Slovenia and Spain. In Picea abies, Pinus sylvestris and Fagus sylvatica from temperate locations in Slovenia, xylem and phloem growth ring boundaries could be identified. In Fagus sylvatica growing at two elevations on Moncayo mountain, Spain, phloem increment consisted of only early phloem. In Pinus sylvestris from the same two sites, growth ring boundaries were not as clear as in temperate Slovenian sites. In some cases we could identify phloem growth ring boundaries but in others it was very doubtful, which could be explained by collapse of the outermost early phloem sieve cells. In Pinus halepensis from all sites, we could only distinguish between collapsed and non-collapsed phloem, while phloem rings could not be identified. Widths of the youngest phloem and xylem annual increments could only be compared when phloem increments could be clearly defined, as with Picea abies, Fagus sylvatica and Pinus sylvestris from temperate sites. The visibility of the growth ring boundary in phloem was not related to the width of annual radial growth. The correlation between xylem and phloem ring widths was high, but moderate between the number of dormant cambial cells and xylem ring and phloem ring widths. Based on the structure of the youngest phloem increments, we concluded that there is no typical annual periodicity in cambial production of phloem cells in trees from certain Mediterranean sites. This may be due to continuous yearlong cell production and the absence of true cambium dormancy, at least on the phloem side, under mild winter conditions.

Forests exhibit strategies to cope with climate change; however, the rate of the changes on forests can be slower than the actual changes in environmental conditions. Forest management policies, such as assisted migration, may help forests to adapt their species distribution to changing climate conditions. Nonetheless, it certainly requires a better knowledge of climate influences on trees to ensure the success of specific management actions. In this study, we apply dendroclimatological methods to investigate the growth response of the main forest species present in Moncayo Natural Park to climate to assess their current relationship and to model these responses over the potential distribution of each species across the study area. Our results revealed large differences in the response of beech, pine and Pyrenean oak to prevailing climate factors and indicated species-specific patterns of climate sensitivity. The general importance of summer conditions for tree growth was confirmed. In addition, we found directional trends in correlation with specific climate factors along spatial gradients; these results are consistent with the autoecology of the studied species. Based on these findings, we present a new model approach that can serve as a key tool for forest managers to design forest communities that are more stable during climatic change.

In the past few decades, temperate forests have been negatively altered by numerous anthropogenic activities and by the impact of ongoing climate change. These changes may require management actions to help preserve some forest tree species. In this sense, highly-detailed knowledge of tree growth and survival across territorial and climatic gradients will be important for forest conservation. We developed a novel approach to determine the optimal zones of forest growth and expansion through climate suitability maps, using a dense tree-ring network of four forest species in Moncayo Natural Park and high-resolution climate data. Our results showed that the mixed-effects models developed using climate data and tree size were able to predict between 65 and 80% of growth variability along the climatic gradient. All studied species were influenced by climate, and the relationship between growth and climate significantly differed along the prevailing climate gradient. Moreover, the suitability maps showed that the current species distribution is limited, and their application may serve as a tool for adaptive management in forests subjected to climate change.

Producción Científica, Drought is one of the key natural hazards impacting net primary production and tree growth in forest ecosystems. Nonetheless, tree species show different responses to drought events, which make it difficult to adopt fixed tools for monitoring drought impacts under contrasting environmental and climatic conditions. In this study, we assess the response of forest growth and a satellite proxy of the net primary production (NPP) to drought in peninsular Spain and the Balearic Islands, a region characterized by complex climatological, topographical, and environmental characteristics. Herein, we employed three different indicators based on in situ measurements and satellite image-derived vegetation information (i.e., tree-ring width, maximum annual greenness, and an indicator of NPP). We used seven different climate drought indices to assess drought impacts on the tree variables analyzed. The selected drought indices include four versions of the Palmer Drought Severity Index (PDSI, Palmer Hydrological Drought Index (PHDI), Z-index, and Palmer Modified Drought Index (PMDI)) and three multi-scalar indices (Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Precipitation Drought Index (SPDI)). Our results suggest that—irrespective of drought index and tree species—tree-ring width shows a stronger response to interannual variability of drought, compared to the greenness and the NPP. In comparison to other drought indices (e.g., PDSI), and our results demonstrate that multi-scalar drought indices (e.g., SPI, SPEI) are more advantageous in monitoring drought impacts on tree-ring growth, maximum greenness, and NPP. This finding suggests that multi-scalar indices are more appropriate for monitoring and modelling forest drought in peninsular Spain and the Balearic Islands., Ministerio de Economía projects: (CGL2015-69186-C2-1-R (Fundiver)), (CGL2015-69985-R (CLIMED)),( CGL2013-48843-C2-1-R (CoMo-ReAdapt)),( AGL2014-53822-C2-1-R (SATIVA)),( XIRONO (BFU2010-21451)),( CGL2014-52135-C03-01), (PCIN-2015-220), and (CGL2016-81706-REDT (Ecometas Network)), (1560/2015 (ECOHIPRO)), Xunta de Galicia, projects:(PGIDIT06PXIB502262PR, GRC GI-1809, ROCLIGAL-10MDS291009PR), INIA (RTA200600117) e Interreg V-A POCTEFA (CANOPEE, 2014-2020-fondos FEDER), Ministerio de Economía y Empresa, postdoctoral grants (MINECO-FPDI 2013-16600; fondos FEDER), Postdoctoral grants (IJCI-2015-25845)

In landscapes that are extremely sensitive to small environmental changes, like some Mediterranean areas, archaeological contexts could present some problems to their interpretation and evolutionary reconstruction. This is the case of Los Pedregales archaeological site, located in the Hoya de Huesca (NE of Spain), where several stone mounds of unknown age and function were found in an extensive badland. The geomorphological, edaphological, and archaeological study, together with radiocarbon and OSL datings and contextualization into the geomorphological regional framework, made it possible to interpret these structures and to establish an evolutionary model. It was determined that they were silos excavated in Pleistocene sands and silts (Unit 1) during the Visigothic and Early Muslim epochs (6th-7th centuries), and that they were later filled with limestone blocks. Successive aggradational and degradational stages (Units 2, 3 and 4) during MCA (Medieval Climatic Anomaly) and LIA (Little Ice Age) periods covered and incised the area, leaving the shape of positive structures included in the badland. Fil: Peña Monné, José Luis. Universidad de Zaragoza; España Fil: Sampietro Vattuone, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Geoarqueología; Argentina Fil: Picazo Millán, Jesús V.. Universidad de Zaragoza; España Fil: Longares, Luis Alberto. Universidad de Zaragoza; España Fil: Pérez Lambán, Fernando. Universidad del País Vasco; España Fil: Badia, D.. Universidad de Zaragoza; España

Wood formation is the primary biological process through which carbon is durably sequestered in woody plants, and is thus a major contributor to mitigate climate change. We analyzed the tree growth patterns of four conifer species across the Iberian Peninsula (IP) based on a dense dendrochronological network (179 sites) combined with a high resolution climate dataset. Generalized linear-mixed models were used to predict the potential tree growth of different pine species under different climate conditions considering different age classes. We found a strong age dependency of tree growth, significant variations across the climate gradients, and a significant interaction of both age and climate effects on the four species considered. Overall, Pinus halepensis was the species with the highest climate sensitivity and the highest growth rates in all age classes and across its distribution area. Due to its stronger plastic character and its potential adaptability, Pinus halepensis was demonstrated to be the most suitable species in terms of tree growth and potentiality to enhance carbon sequestration in the IP. Since its potential distribution largely exceeds its actual distribution, P. halepensis arises as a key species to cope with future climate conditions and to keep fixing carbon regardless of the climatic circumstances.

16 Pags.- 3 Tabls.- 5 Figs., Forecasted increase drought frequency and severity may drive worldwide declines in forest productivity. Species‐level responses to a drier world are likely to be influenced by their functional traits. Here, we analyse forest resilience to drought using an extensive network of tree‐ring width data and satellite imagery. We compiled proxies of forest growth and productivity (TRWi, absolutely dated ring‐width indices; NDVI, Normalized Difference Vegetation Index) for 11 tree species and 502 forests in Spain corresponding to Mediterranean, temperate, and continental biomes. Four different components of forest resilience to drought were calculated based on TRWi and NDVI data before, during, and after four major droughts (1986, 1994–1995, 1999, and 2005), and pointed out that TRWi data were more sensitive metrics of forest resilience to drought than NDVI data. Resilience was related to both drought severity and forest composition. Evergreen gymnosperms dominating semi‐arid Mediterranean forests showed the lowest resistance to drought, but higher recovery than deciduous angiosperms dominating humid temperate forests. Moreover, semi‐arid gymnosperm forests presented a negative temporal trend in the resistance to drought, but this pattern was absent in continental and temperate forests. Although gymnosperms in dry Mediterranean forests showed a faster recovery after drought, their recovery potential could be constrained if droughts become more frequent. Conversely, angiosperms and gymnosperms inhabiting temperate and continental sites might have problems to recover after more intense droughts since they resist drought but are less able to recover afterwards., This study was financially supported by the Spanish Ministry of Economy projects: CGL2015‐69186‐C2‐1‐R (Fundiver), CGL2015‐69985‐R (CLIMED), CGL2013‐48843‐C2‐1‐R (CoMo‐ReAdapt), AGL2014‐53822‐C2‐1‐R (SATIVA), XIRONO (BFU2010‐21451), CGL2014‐52135‐C03‐01, PCIN‐2015‐220, and CGL2016‐81706‐REDT (Ecometas Network). The study was also funded by IMDROFLOOD (Water Works 2014, EC) and INDECIS (European Research Areas for Climate Services) projects. This work also benefited from funding from Xunta de Galicia (PGIDIT06PXIB502262PR, GRC GI‐1809, ROCLIGAL‐10MDS291009PR), INIA (RTA2006‐00117), and Interreg V‐A POCTEFA (CANOPEE, 2014‐2020‐FEDER funds) projects. RSS and AG were supported by Postdoctoral grants (IJCI‐2015‐25845 and MINECO‐FPDI 2013‐16600; FEDER funds).

The most important stratified screes of the Iberian Range are found in Sierra de Albarracín. These slope deposits have been traditionally considered, without absolute datings, as having been formed during various Pleistocene cold phases. The aim of this paper is to establish the sedimentological, morphological, chronological, and paleoenvironmental characteristics of these deposits through the study of four profiles recorded in the Calomarde canyon (El Rollo, El Molino, and Royuela) and Toril. The most representative profile is that of El Rollo as it is formed by basal tufa and stratified scree layers separated by paleosoils. Radiocarbon datings obtained from paleosoil samples show that the sequence ranges between the early and middle Holocene. The profiles from El Molino and Royuela, as well as the upper levels of Toril, complete the sequence showing deposits from upper Holocene (Bronze Age and ‘Little Ice Age’). These data show the oscillations during the Holocene between colder phases, represented by the stratified screes, and warmer–wetter phases with soil development and local tufa deposits. This geomorphological and pedological response to the Holocene climatic variability shows its clearest records in the canyons. However, there are almost no Pleistocene accumulations – with the exception of that of Toril (minimum age of

A high-resolution daily gridded precipitation dataset was built from raw data of 12,858 observatories covering a period from 1950 to 2012 in peninsular Spain and 1971 to 2012 in Balearic and Canary Islands. The original data were quality controlled and gaps were filled on each day and location independently. Using the serially-complete dataset, a grid with a 5 x 5 kilometres spatial resolution was constructed by estimating daily precipitation amounts and their corresponding uncertainty at each grid node. Daily precipitation estimations were compared to original observations to assess the quality of the gridded dataset. Four daily precipitation indices were computed to characterize the spatial distribution of daily precipitation and nine extreme precipitation indices were used to describe the frequency and intensity of extreme precipitation events. The use of the total available data in Spain, the independent estimation of precipitation for each day and the high spatial resolution of the grid allowed for a precise spatial and temporal assessment of daily precipitation that are difficult to achieve when using other methods, pre- selected long-term stations or global gridded datasets. SPREAD dataset is publicly available at http://dx.doi.org/10.20350/digitalCSIC/7393.

An interdisciplinary non-invasive research strategy combining the analysis of archival documents, detailed geomorphological mapping, Quaternary stratigraphic studies, analysis of ceramics, and radiocarbon dating was designed to reconstruct the evolution of the Mezimegeer–Juslibol Castle, northeastern Spain. This fortress had great strategic importance in the siege and conquest of the nearby Islamic city of Saraqusta by the Christians in A.D. 1118. The castle and moat complex was built in the mid-10th century. In the mid-12th century, its rapid degradation began, as it is shown by this geoarchaeological study of the sediments in the moats. Its present state of decay is due to later erosion that is promoted by the unstable bedrock of Miocene gypsum, highly deformed gravels that form a Pleistocene fluvial terrace, and the environmental aridity.

A quality-controlled and enhanced database of 38 temperature and 52 precipitation stations was developed for Slovenia, a transitional area between Mediterranean, Alpine and continental climatic regimes, covering the period 1951–2007. Mean annual temperatures significantly increased in nearly all of Slovenia (except western areas) at rates between 0.15 and 0.36 °C/decade. Warming was most intense strongest in summer and spring in north-eastern Slovenia (0.3–0.4 °C/decade) and weakest in autumn. Precipitation trends were heterogeneous. Annual precipitation decreased significantly in the north-western part, at 3–6 % per decade. During spring and summer, decrease in rainfall by 3–6 % was detected in western Slovenia. No significant trends were found for the autumn season. In winter, precipitation decreased, by 3–12 % per decade, in particular in north-western Slovenia. As observed also elsewhere in Central Europe, changes in large-scale atmospheric circulation patterns may have contributed to the observed long-term warming and drying in Slovenia. However, the strong warming in summer and spring, that is almost twice the trend observed in neighbouring countries, could be enhanced by drier soils caused by the decrease in winter precipitation in Slovenia.

An analysis was made of the Precipitation Concentration Index using the new MOPREDAS database of monthly precipitation in Spain (Monthly Precipitation Data base of Spain). The database was compiled after exhaustive quality control of the complete digitalized Spanish Meterological Agency (AEMet) archives and contains a total set of 2670 complete and homogeneous monthly precipitation series from 1946 to 2005. Thus, MOPREDAS currently holds the densest information available for the 1946–2005 period for Spain and ensures a high resolution of results. The Precipitation Concentration Index (PCI) is a powerful indicator of the temporal distribution of precipitation, traditionally applied at annual scales; as the value increases, the more concentrated the precipitation. Furthermore PCI is a part of the well-known Fournier index, with a long tradition on natural system analyses, as for example soil erosion. In this paper, the mean values of annual, seasonal and wet and dry periods of PCI in the conterminous Spain and for two normal periods (1946–1975 and 1976–2005) were studied. Precipitation in Spain follows a general NW-SE spatial pattern during the wet (months) period due to the Atlantic storm track, while during the dry (months) period, it follows a predominantly N-S spatial pattern. As a result, the annual values of PCI combine the two patterns and show a SW-NE PCI gradient. The analyses of the two sub-periods show significant changes in the precipitation occurred in conterminous Spain from 1946 to 2005, and precipitation concentration increased across most of the IP. At an annual scale, PCI increases mostly due to an increase in precipitation concentration during the wet season. At a seasonal scale significant changes were detected between 1945–1975 and 1976–2005, particularly in autumn (increase of PCI values), while changes in winter, spring and summer were mostly localized and not generalized (both increase and decrease). Changes in PCI seem to be complex and appear to be related to global atmospheric features and synoptic and local factors affecting precipitation trends. We discuss the possible explanation linked to the atmospheric pattern and monthly trends and their implications.

The spatial variability of seasonal precipitation regimes in the Iberian Peninsula is overlapped by complex patterns of temporal variability. Consequently, traditionally described space domains of seasonal rainfall regimes in Spain may be changing. In this paper we evaluate seasonal precipitation trends over Spanish conterminous land to determine how these trends are modifying traditionally described seasonal rainfall regimes in the study area. To this end, we used a recently developed high resolution grid (1/10 degree longitude and latitude) derived from the MOPREDAS database, comprising 2670 complete and homogeneous monthly precipitation series for the 1946–2005 period, and calculated and compared the seasonal precipitation regimes observed in two consecutive 30-year periods (1946–1975 and 1976–2005). We found that, from the total of 24 possible permutations between winter, spring, summer and autumn as dominant and subdominant precipitation seasons, 12 coexist over Spanish conterminous land. Moreover, there have been notable changes in the last 30 years, affecting not only the most prominent season, but also the variant within each regime. The trends observed therefore indicate that, on comparing the two 30-year subperiods, the percentage of territory in which winter constitutes the dominant precipitation season decreases from 51.1% to 42.7% of the total study area. Similarly, spring was the dominant precipitation season in 36.1% of the territory in the 1946–1975 period, whereas in the 1976–2005 period, it is the dominant one in less than half (15.1%) the territory. This contrasts with areas where autumn constituted the main precipitation season, which increased from 10.8% (restricted to the Mediterranean coast) to 41.4% of the territory. Within the context of climate change, these variations among seasonal precipitation patterns can be explained by (1) a subtropicalization of the IP climate with a reduction of rainfall amounts from winter to summer and (2) an increase in the autumn rainfall percentage.

This is a study of the changes in annual and seasonal precipitation amounts and variability, during the period 1951–2000, using MOPREDAMES. This dataset includes 1113 complete and homogeneous monthly precipitation time series from the Mediterranean Iberian Peninsula (IP), and corresponds to the five official Spanish hydrological divisions which drain into the Mediterranean Sea. The time series of annual and seasonal precipitation were used to test for trends. The absolute value of the anomaly time series was also tested for trends to identify changes in interannual variability of precipitation. The significance of these changes was assessed using the non-parametric Spearman rank test. The intensities of observed changes, both on mean values and variability, were estimated by using linear regression techniques. Finally, we analysed the area affected by different trends by using raster maps and spatial statistics, in addition to calculating the global balances for the five hydrological divisions. We detected high variability in precipitation regimes and conditions in the study area; nevertheless, a decrease in seasonal and annual precipitation has predominated in the east of the IP during the second half of the 20th century. On an annual scale, precipitation has diminished over 90.1% of the study area. Additionally, a high percentage of the territory was affected by diminishing precipitation at a seasonal level: 85% (of territory) in summer, 82% in spring, 64% during winter and 61% in autumn. Taking the study area as a whole, seasonal precipitation decreases are ranked as follows: summer (−22.5%), spring (−19.3%), winter (−7.3%), and autumn (−5.2%), with a decrease in the value of the global mean annual precipitation − 12.4%. We also detected an increase of precipitation variability in winter (+23.5%) and summer (+11.4%), and a decrease in autumn and spring (−14.9 and − 16.8%, respectively) with a global mean value of + 7.8%. Copyright © 2008 Royal Meteorological Society

The risk of erosion and desertification is one of the main environmental concerns in the Mediterranean Iberian Peninsula. Changes in precipitation are expected in Mediterranean areas because of climate change, but predictions are not certain. For this reason, dense precipitation databases are required to explore observed changes in the amount, concentration and variability of precipitation, to gain a clearer understanding of the dynamics involved in the main climatological agent of erosion. For this study, we took the recently developed MOPREDAMES dataset, which includes 1113 complete and homogeneous monthly rainfall series from the Mediterranean fringe of the Iberian Peninsula (IP) covering the period 1951–2000. These were used to calculate and analyse trends in Total Annual Precipitation (Pt), the Precipitation Concentration Index (PCI) and Modified Fourier Index (MFI). Our results show that, although there were decreases in annual rainfall, increases in the concentration of precipitation also predominated in the Mediterranean Iberian Peninsula during the period 1951–2000. However, spatial variability of these trends is high, and changes in rainfall erosivity exhibit a complex spatial pattern. Thus, decreases in rainfall erosivity are detected under semiarid conditions (Central Ebro basin and South East IP), while increases mainly occur in dry and sub-humid areas. We present a detailed spatial description of the results and discuss their implication for the risk of erosion and desertification in different regions of the study area. Copyright © 2009 John Wiley & Sons, Ltd.

A Holocene alluvial morphostratigraphy, based on geomorphological mapping, sedimentological analysis, soil development and radiocarbon chronology is presented for the semiarid Blanca basin in the Bardenas Reales Natural Park (NE, Spain). Four morphopedosedimentary alluvial units (MU1, MU2, MU3 and MU4) were differentiated, which may correspond to two palaeogeographical stages. The first one includes the morphopedosedimentary unit MU1 and is the most extensive in the area. It is made up of a complex aggradation (fill up) sequence comprising a braided channel system, a sand–mud flat (9200–7900 cal BP) and a playa-lake environment related to a nearly closed depression. An intensive fluvial entrenchment period is recognized, leading the opening of the Blanca basin, before the second stage that includes the units MU2, MU3 and MU4. This set of units forms a sequence of cut-and-fill and nested fill terraces recording the alluvial activity in the Blanca basin during the last 6 ka. The MU2 unit, 5900–3300 cal BP in age, represents a period of high geomorphic instability with rapid alluvial sedimentation/channel incision oscillating changes. On the other hand, the MU3 unit has an age of 1050–500 cal BP and appears as a thin extensive alluvial cover overlying previous units. Finally, the MU4 unit comprises superposition of numerous flood depositional sequences, centimetric in scale, dated from 450–10 cal BP. The established soil chronosequence supports the numerical chronology of the four units. These accumulation periods (MU1, MU2, MU3, MU4) are associated with dry phases and/or high hydrological variability (floods and droughts) at a regional scale. Changes on the North Atlantic atmospheric circulation mode over Southern Europe may provide the key to explain the nature of alluvial activity during Holocene in Bardenas Reales., Projects BTE2003-01296 and CGL2006-08973/BTE of the Spanish Government and the European Regional Development Fund have supported this work. We thank Alejandro Urmeneta (Junta de Bardenas Reales de Navarra) for collaboration with permissions and technical support in the field and Sophie Baker for the assistance with editing this manuscript. This is a contribution by PALEOQ and Cuencas Sedimentarias Continentales groups (Aragón Regional Government).

Wood formation in European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) was intra-annually monitored to examine plastic responses of the xylem phenology according to altitude in one of the southernmost areas of their distribution range, i.e., in the Moncayo Natural Park, Spain. The monitoring was done from 2011 to 2013 at 1180 and 1580 m a.s.l., corresponding to the lower and upper limits of European beech forest in this region. Microcores containing phloem, cambium and xylem were collected biweekly from twenty-four trees from the beginning of March to the end of November to assess the different phases of wood formation. The samples were prepared for light microscopy to observe the following phenological phases: onset and end of cell production, onset and end of secondary wall formation in xylem cells and onset of cell maturation. The temporal dynamics of wood formation widely differed among years, altitudes and tree species. For Fagus sylvatica, the onset of cambial activity varied between the first week of May and the third week of June. Cambial activity then slowed down and stopped in summer, resulting in a length of growing season of 48–75 days. In contrast, the growing season for P. sylvestris started earlier and cambium remained active in autumn, leading to a period of activity varying from 139-170 days. The intra-annual wood-formation pattern is site and species-specific. Comparison with other studies shows a clear latitudinal trend in the duration of wood formation, positive for Fagus sylvatica and negative for P. sylvestris. Published

Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees to adverse environmental conditions. The demonstrated relationship of MR formation to ECE across this dendrochronological network in the Mediterranean basin shows the potential of MR analysis to reconstruct the history of past climatic extremes and to predict future forest dynamics in a changing climate. This study was supported by Spanish Ministry of Education and Science co-funded by FEDER program (projects: CGL2012-31668 and CGL2015-69985-R), by the Slovenian Research Agency (programs P4-0015 and P4-0107), by the LLP ERASMUS bilateral agreement between the University of Ljubljana and the University of Alicante, and the USDA Forest Service. The article is based upon work from COST Action FP1106 STReESS, supported by COST (European Cooperation in Science and Technology).

Se establece un diagnostico sobre la dinámica vegetal de un mosaico de formaciones vegetales denominado "pradera-tamarizal" localizado en el sector NO del Galacho de Juslibol.

Se presenta la problemática de un espacio de ribera, la arboleda del "Soto y Partinchas", que contacta con el Espacio Natural Protegido del Galacho de Juslibol (Zaragoza). Se diagnostica su estado actual, sus funciones y la tendencia evolutiva prevista para, finalmente, exponer diferentes alternativas de actuación o gestión.

Resumen: En este trabajo, se plantea el estudio zoogeografico del hayedo del Moncayo (Aragon, Espana), en relacion con la situacion limite de distribucion de dicha formacion vegetal. Su comparacion con la fauna detectada en diferentes hayedos, permite detectar presencias y ausencias faunisticas significativas, las cuales, indican la situacion ecologica y el verdadero caracter corologico de esta masa boscosa sometida a estudio. Palabras clave: Zoogeografia, corologia, fauna, hayedo.

Conducting biodiversity surveys is expensive and time consuming and we cannot always invest as much time as needed conducting field work. To compensate for such deficiencies, scientists can benefit from advanced techniques of species distribution modelling. Data on species distribution is essential for the correct conservation and management of the species and their habitats. The objective of this study has been to predict the distribution range of four lizard species in Qatar that were found in few locations during field surveys conducted in 2012-2013, and that we believe that could be present in a larger range. The species examined were: the Schmidt´s fringe-toed lizard, Acanthodactylus schmidti (with 18 field observations), the toad-headed agama, Phrynocephalus arabicus (with 27 field observations), the Arabian sand gecko, Stenodactylus arabicus (with 22 field observations) and the Eastern skink, Scincus mitranus (with 8 field observations). The four species have been only observed in the southern part of the Qatar country. To make predictions about the potential distribution of these lizard species we used climatic data obtained from the WorldClim database, and remote sensing data (Landsat 8 Image), from which we obtained high resolution data as surface temperature, and other features derived from the land surface reflectivity at different wavelenghts. We generated new maps for the four lizard species in Qatar based on different ecological niche models (ENMs). All these models appeared to be ‘good’, with a AUC value >0.8. There are not significant differences between bioclimatic and remote-sensing maps. However the bioclimatic maps were the ones that visually matched better with the observed distribution of the species. Furthermore, bioclimatic maps can be less reliable due to the low number of climatic observatories in the area used to build the databases. We found some differences between the predicted distribution maps depending on the environmental covariates used, being the relative rank between pairs of maps of any species always near 0.5. Despite the limitations of the models, they appear to be a good predictive tool for lizard distribution ranges. Future advances in the knowledge of the environment together with environmental and climatic maps of higher resolution will improve ecological niche modelling in Qatar.

En todas las poblaciones naturales de aves rapaces existen unidades reproductoras (UR) cuya productividad, entendida como pollos volados/año, es baja o nula. Las molestias humanas en las zonas de nidificación han sido una de las causas más relacionadas con el descenso de la productividad de muchas aves rapaces (Richardson y Miller, 1997). Según Arroyo y Razin (2006) las actividades humanas cercanas a los nidos del Quebrantahuesos (Gypaetus barbatus L.) pueden causar molestias en la reproducción. Los vigentes planes de recuperación de la especie en la Cordillera pirenaica contemplan acciones específicas para evitar el fracaso reproductivo, mediante la aplicación de medidas preventivas de factores de perturbación: molestias por batidas de caza, escalada deportiva, etc. Durante los últimos 10 años el deporte de escalada en Aragón (en todas sus modalidades) ha experimentado un aumento en cuanto al número de escaladores y sectores donde se practica. Con el fin de conocer las posibles repercusiones de la escalada en roca en la conservación del Quebrantahuesos se ha recopilado información sobre sectores de escalada en la provincia de Huesca. Posteriormente dicha información ha sido georreferenciada espacialmente y se le han aplicado diversos métodos de análisis geoespacial con técnicas SIG en el entorno ArcGis. El objetivo ha sido realizar una aproximación al análisis de la posible relación entre el deporte de escalada y la nidificación de la especie. De un total de 315 nidos conocidos de Quebrantahuesos en Aragón (2011), se ha comprobado que el 11,75% de estos (n= 37) podrían estar afectados por la escalada en roca.

Resumen: La dinamica del curso bajo del rio Gallego ha cambiado de forma significativa tras las transformaciones generadas en las ultimas decadas por la accion humana. Como testimonio de su funcionamiento actual, se analiza uno de los meandros de este tramo fluvialdurante las crecidas de 2003-2004, en el que se pone de manifiesto su comportamiento mixto. Por una parte, en momentos de crecida es capaz de generar barras lobuladas y transversas con una trayectoria y funcionamiento mas cercano al sistema braided, mientras que al descender su caudal genera rupturas de barras, que alimentan la formacion de point-barsy la recuperacion de sutrazado meandriforme habitual. Esta dinamica alternante genera rupturas de pendiente, con rapidos que,en ocasiones, se venincrementados localmente por cambios en la resistenciadel sustrato, al que consigue accederel rio como consecuencia de los procesos de incision activados en epoca reciente. Palabras clave:Rio Gallego, dinamica fluvial, barras fluviales, incision.

Se presenta un estudio que valora las comunidades faunísticaspresentes en el Aiguabarreig del Segre, Cinca y Ebro desde un punto devista geográfico, considerando su distribución espacial y las relacionesque se establecen entre los distintos ambientes naturales que configuraneste territorio húmedo. A través de la creación de áreas faunísticas apoyadasen el manejo de SIG y la interpretación de los datos recogidos encampo, se ha obtenido una división de la zona de estudio en función delos hábitats potenciales para proceder a su valoración en base a criteriosde naturaleza ecológica.

Se estudia la comunidad aviar presente en el sector de piedemonte del Sistema Ibérico zaragozano que forma parte de la Comarca del Campo de Borja (Zaragoza, España), durante la época invernal y reproductora. Se analizan los parámetros de Diversidad, Riqueza específica y Constancia para el conjunto del área de estudio, así como para el humedal artificial conocido como “La Estanca de Borja”. Además se procede al análisis de los cambios observados en la composición de esta comunidad aviar entre 1970 y 2009, comparándolos con los cambios que se han producido durante dicho periodo en cuanto al uso del territorio y los hábitats establecidos para el estudio de la dinámica temporal de los mismos.