NE Iberian Peninsula Research Articles

An observational analysis of two companion supercell storms over complex terrain

This article analyses two long-lived supercell thunderstorms formed on 11th May 2017 afternoon in a complex topographic area in northern Catalonia (NE Iberian Peninsula). The objectives of this paper are (i) to document a case study that affected a mountainous region in the southern side of the Pyrenees, (ii) to describe thermodynamic and dynamic environmental conditions, (iii) to study how the topography affects the life cycle of both storm cells and (iv) to demonstrate the high correlation between Lightning Jump and radar parameters in complex terrain. ERA5 reanalysis was used to assess the synoptic framework and environmental storm conditions, whereas remote-sensing data (Doppler radar, satellite and lightning observations) and terrain characteristics were considered to study the evolution of both cells. Reanalysis data revealed some differences between preconvective environments for both thunderstorms, showing more favourable conditions for supporting supercells (i.e. stronger deep-layer shear) for the first thunderstorm than for the second one. The analysis suggests substantial interaction between topography and storm cells, influencing their internal dynamics and the development of mesocyclones. The results of this study contribute to enhance our understanding of supercell storms evolution on mountain areas and may be useful to increase the situational awareness of weather forecasters in future similar convective storm events over complex terrain regions.

A study on correlations between precipitation ETCCDI and airborne pollen/fungal spore parameters in the NE Iberian Peninsula

Precipitation is one of the meteorological variables usually involved in the aerobiological studies, which presents a complex relationship with atmospheric levels of pollen and fungal spores and the temporal characteristics of their seasons. This complexity is due in a large part to rainfall's twofold impact of having, prior to pollination, a positive influence on subsequent pollen production and of contributing, during pollination, to pollen removal from the air through a wash-out effect. To better explore this impact, we place particular emphasis on extreme rainfall by calculating the correlation between airborne pollen and fungal spore parameters and the precipitation indices that the Expert Team on Climate Change Detection and Indices (ETCCDI) proposed for characterising climate extremes. Parameters for twenty-seven pollen and fungal spore taxa measured in six aerobiological stations in the NE Iberian Peninsula have been considered. We have distinguished between annual and winter ETCCDI in order to compare the correlations between extreme rainfall and airborne pollen concentrations and to avoid the wash-out effect as far as possible. Results show a positive influence from an increase in moderately extreme winter rainfall, specifically on subsequent pollen/fungal spore production: the percentage of all possible significant correlations is higher for winter than for annual rainfall. Furthermore, while annual rainfall in this region has nearly the same number of positive as negative correlations, the positive correlations for winter rainfall are more than twice that of the negative ones. The seasonal consideration on rainfall ETCCDI made with the aim to avoid the confounding overlapping of different rainfall impacts has led to more sharpened observations of its positive and negative effects on airborne pollen and fungal spore concentrations.

Site formation processes, human activities and palaeoenvironmental reconstructions from archaeobotanical records in cave and rock-shelter sites in NE Iberia

The main aim of this paper is to evaluate the potential of cave and rock-shelter sites for palaeoecological and archaeobotanical research. Climate conditions in the Mediterranean region and the depositional and post-depositional dynamics involved in the formation processes of open-air sites cause, in many cases, poor conservation of archaeobotanical remains, especially in the case of pollen, affected by oxidation and other taphonomic agents. However, more stable temperature and humidity, as found in cave and rock-shelter sites, provide optimum conditions for the preservation of vegetal remains. This study presents integrated archaeobotanical data from several NE Iberian sites, with occupations from the Middle Palaeolithic to the Bronze Age. On the one hand, the diachronic study of the pollen record in archaeological stratigraphies reconstructs vegetation evolution and abrupt climate changes during the Pleistocene and the Holocene. On the other hand, archaeopalynology reveals the need to consider different taphonomic agents in the interpretation of pollen records in archaeological cave and rock-shelter sites, especially the anthropogenic input of plants to the archaeological contexts. The study of anthracological remains offers a picture of the surrounding wooded landscape, and provides data to characterise vegetal resource management and to verify which plants were brought to the cave. Finally, the carpological record shows the presence of edible wild fruits from bushes and trees in the Pleistocene and beginnings of the Holocene, and cultivated and synanthropic plants from the Middle Holocene onwards.

A Spatial Connectivity Approach to Landscapes of Conflict: Julius Caesar and the Assault to Puig Ciutat (NE Iberian Peninsula)

Landscape plays a vital role in the development of military campaigns through the definition of geostrategic landmarks that structure the control of the territory, the imposition of constraints to the movement of armies and the identification of features that facilitate defence against attackers. These factors are linked to the study of past spatial mobility which is typically done by finding optimal pathways between pairs of points using Least-Cost Path analysis. This emphasis on optimality may not be ideal for case studies that need a general approach to spatial connectivity such as the study of conflict-related dynamics. Connectivity modelling based on Circuit Theory (CT) is an alternative approach to spatial mobility that captures the connectivity of an entire region identifying not only optimal paths but also bottlenecks, dead-ends and any other spatial feature that may impact movement. We present here a framework to study landscapes of conflict using connectivity modelling; the framework combines CT, visibility analysis and statistical hypothesis testing to understand the reasons behind the assault and destruction of Puig Ciutat (NE Iberian Peninsula) during Julius Caesar’s civil war. Results suggest that the site exerted decisive control over a highly connected area linking two possible logistical bases (Emporion and Massalia) to the armies fighting at Ilerda (49 BC).

Landscape footprints of peopling and colonisation from the Late Bronze Age to Antiquity in the coastal hinterland of Emporion-Emporiae, NE Iberia.

The Empordà plain attests to a remarkable mixture of Late-Holocene cultural exchanges and colonial processes. This includes the founding of Emporion, the earliest Greek colony in Iberia, and of the Roman city of Emporiae. This study aims at assessing landscape changes related to indigenous and colonial settlement in this unique scenario where the shaping of cultural landscapes occurred within a dynamic coastal ecosystem. We carried out a high-temporal resolution palaeoenvironmental study in Els Estanys, a palaeowetland located in the vicinity of Emporion-Emporiae. Palynological, sedimentological and geochemical indicators were coupled with available archaeological and archaeobotanical data-sets. Between 1100 and 800 cal BC, the settling of Urnfield Late Bronze societies resulted in the sustained clearance of woodlands and moderate agropastoral exploitation of coastal ranges. During this period, marine-influenced lagoonal areas were poorly exploited. During the Iron Age (800–450 cal BC), a threshold in the landscape construction of the area occurred with the first pastoral exploitation of lagoonal areas, intensified cereal cultivation, controlled burning, and enhanced deforestation following the settlement of Iberian groups. Greek colonisation (580–200 cal BC), did not trigger intensified farming exploitation or landscape clearance, nor did it imply the introduction of new land uses or crops in the hinterland. Exploitation of the latter continued relying on cereal cultivation and grazing, as before, suggesting the permanence of indigenous landscapes and practices in the hinterland. To the contrary, urban and periurban landscapes played a significant role in the construction of the colonial landscape with the introduction of olive groves likely as ornamental trees. Roman conquest and colonisation of the area constituted a new threshold in the occupation and management of the hinterland with (1) intensified rural settlement; (2) expansion of wet pastures and removal of littoral woodlands; (3) development of diversified cropping activities; and (4) development of mining and smelting activities.

The Guinardera quarry (Sant Martí de Tous, Barcelona): A new chert exploitation location during historical times

In 2014, an anthropic accumulation of chert material was discovered in La Guinardera area, at the southwest of the Sant Martí de Tous town (Barcelona, NE Iberian Peninsula). In 2018 a first archaeological intervention was carried out in two locations: La Guinardera and La Guinardera Nord. After the fieldworks, these two accumulations were interpreted as chert workshops. These workshops are in the St. Genís Formation, included within La Noguera lacustrine system and dated to the Priabonian age (upper Eocene). The St. Martí de Tous area presents shallow lacustrine conditions typical of sabkha environments, in which layers of gypsums and sandy lutites are interspersed with tabular red sandstone levels, yielding different varieties of chert.
 The Guinardera chert is characterized by a fairly homogeneous matrix, presenting a fine texture, with a microcrystalline and spherulitic length-slow chalcedony matrix, and a combination of grey colours, in general of dark hues, with an opaque diaphaneity but translucent at the edges.
 The archaeological assemblage from La Guinardera Nord site allows us to identify a chert workshop for the production of gunflints. The heterogeneity of the assemblage at La Guinardera site precludes assigning it to any single chrono-cultural period or function.
 The technological characterization of La Guinardera Nord site reveals distinctive attributes of a gunflint workshop that can be differentiated from prehistoric workshops. The presence of square and thick preforms, oxide traces on butts and ventral faces, marked bulbs and thick platforms, together with fresh edges on flakes and blades and the near-absence of patinated materials, corroborate it.
 The presence of these two deposits within the above-mentioned formation shows us a repeated landscape exploitation pattern for raw material extraction, since references chert use range from the Middle Palaeolithic (e.g., Abric Romaní) to historical times (e.g., La Guinardera Nord).

Origin of the Coloured Karst Fills in the Neogene Extensional System of NE Iberia (Spain)

Karst fills from the onshore Penedès Basin and offshore València Trough display red, pink, orange and ochre colours. Their Mössbauer spectra indicate that Fe3+ contained in goethite is the dominant species in reddish-pink fills, whereas Fe2+ contained in dolomite and clays is more dominant in the orange and ochre ones. The lower δ13C values and higher 87Sr/86Sr ratios of the karst fills with respect to their host carbonates can reflect the input of soil-derived CO2 and an external radiogenic source into the karst system. This geochemical composition, together with the non-carbonate fraction of the fills, consists of authigenic and transported illite, illite-smectite interlayers, as well as kaolinite, chlorite, pyrite, quartz, ilmenite, magnetite, apatite and feldspar, account for a mixed residual-detrital origin of fills. This polygenic origin agrees with that of the terra rossa sediments described worldwide. The different colours of karst fills are attributed to fluctuations in the water table, which control the Eh/pH conditions in the karst system. Thus, reddish colours reflect low water table levels and oxidising episodes, and orange and ochre ones reflect high water table levels and more reducing episodes. The greenish colours of fills could be related to fluctuations in the Fe3+/Fe2+ ratio.

The enriched Variscan lithosphere of NE Iberia: data from postcollisional Permian calc-alkaline lamprophyre dykes of Les Guilleries

Post-collisional mafic dykes crosscut the Paleozoic metamorphic basement and late-Variscan plutons in Les Guilleries massif (Catalan Coastal Ranges, NE Iberia). The predominance of mafic phenocrysts, porphyritic texture, abundant amphibole, high MgO and volatile content, together with crustal-like trace-element patterns indicate that the dykes correspond to calc-alkaline lamprophyres, mainly spessartites. Their enrichment in LILE, HFSE and REE and initial Sr-Nd isotopic compositions (87Sr/86Sri between 0.70851 and 0.71127, epsilon Ndi between -5.23 and -4.63) are consistent with an enriched subcontinental lithospheric mantle source. U-Pb ages of matrix titanite crystals yield concordia ages of 262±7Ma, congruent with crosscutting relationships. Postmagmatic processes are evidenced by intense chloritization and albitization of the lamprophyres, together with systematic variations of Na2O vs SiO2, K2O, CaO, Ba, Rb, Cs, Pb, Sr, Tl, and Zn, and possibly the removal of F. The geochemical and geochronological data support an orogenic geochemical affinity, in accordance with the transitional tectonic regime between Variscan compression/transpression and post-collisional transtension/extension, related to the fragmentation of Pangea and thinning of the lithosphere. The lamprophyre dykes studied could represent the youngest pulse of Variscan orogenic magmatism and, therefore, mark its end in NE Iberia before the onset of the generalized Triassic extension.

Micro- and Nanotexture and Genesis of Ball Clays in the Lower Cretaceous (SE Iberian Range, NE Spain)

Ball clay deposits in the SE of the Iberian Range (NE Iberian Peninsula) consist of Albian clays and siltstones with greyish and blackish colors, interbedded with subbituminous coals. The ball clays are nowadays mined for the manufacture of white color ceramics. The mineralogy of these deposits consists mainly of kaolinite, illitic phases, and quartz. The euhedral to sub-euhedral morphology of the kaolinites suggests their in-situ origin. The anhedral morphology of the illites and the presence of frayed illites suggest a detrital origin. At the micro-scale, authigenic kaolinite booklets are observed filling pores and forming mica/kaolinite intergrowths, in which the kaolinite grows between the cleavage sheets of pre-existing detrital mica. At nanometer scale, illite/smectite (IS) phases are detected forming interlayers with mica and kaolinite, and evidence of the replacement of mica by kaolinite is observed. The matrix consists of defective illite and kaolinite, and random mixed layers of kaolinite-I/S (Kln-IS), illite-I/S (Ilt-IS), and I/S-smectite (IS-S). The textures of illite and the presence of different types of mixed layers suggest that the expandable phases and kaolinite are products of mica alteration. The effectivity of the alteration was probably a consequence of the low pH that occurred in the environment due to the presence of abundant organic- and acidic- rich fluids.

The complete skeleton of a straight-tusked elephant calf from Cova del Rinoceront (Late Pleistocene, NE Iberian Peninsula): New insights into ontogenetic growth in Palaeoloxodon antiquus

A nearly complete skeleton of an elephant calf was excavated between 2012 and 2014 from breccia deposits in a vertical karstic cavity named Cova del Rinoceront, exposed during limestone quarrying. The skeleton was found in the 120 cm-thick breccia layer III (Unit 1) of the 11 m-long sedimentary sequence filling the cavity. IRSL (128–129 ka) and AAR (126–142 ka) dating indicate that the layer was probably deposited during MIS 5e (∼115–135 ka). The diagnostic morphological traits of the occlusal surface of the molariform teeth, their position in the tooth progression and wear indicate that the skeleton belongs to a Palaeoloxodon antiquus calf about 5 years old, with a putative height at the shoulder of about 178–187 cm and a weight of about 1450–1500 kg. The sex cannot be confidently determined because the tusks were poorly preserved and the young age reduces the diagnostic value of the pelvis girdle.The rarity of calf skeletons in the fossil record of continental straight-tusked elephants renders the Cova del Rinoceront individual of great interest for better understanding the ontogenetic processes in continental straight-tusked elephants.The results obtained evidence, on the one hand, the difficulties entailed in properly assessing the ontogenetic growth process, given the low number of fully informative specimens of straight-tusked elephants known to date. On the other hand, they indicate an early beginning of distal epiphyseal fusion in humerus and tibia and of the proximal epiphysis in radius. Moreover, the nearly fused lateral epicondylus and condylus and the unfused and separate diaphysis and epiphysis on the medial side of the right femur suggest not only that fusion patterns may show high levels of intraspecific variation, but also that the process of epiphyseal fusion may vary in the homologous bones of a single individual.Notwithstanding the limitations resulting from the preservation status of the calf bones, our analysis yielded sufficient information to infer the ontogenetic age of the Cova del Rinoceront elephant, estimate its body mass and evaluate allometric growth in P. antiquus long bones. We obtained slightly different results when analysing samples that did or did not include the Cova del Rinoceront calf. In the former sample, confident isometry was limited to a few predictors but could not be excluded because for most of the independent variables, isometry and negative correlation were roughly balanced. Most of the dependent and independent variables showed the same or a similar scale ratio, but fewer responded almost similarly to bending stresses imposed by loading under their own weight. When the calf was excluded from analysis, negative or possibly negative correlations and variables responding almost similarly to bending stresses imposed by loading under their own weight prevailed. However, the hypothesis that some changes in limb bone proportions occurred during ontogenetic growth requires further support from an analysis of large samples of fully informative mature and immature P. antiquus individuals.

First record of amphibian mortality associated with the fungus <em>Batrachochytrium dendrobatidis</em> in Catalonia (NE Spain)

We report the first cases of mortality in anurans associated with the presence of the fungus Batrachochytrium dendrobatidis at four different localities from Catalonia (NE Iberian Peninsula, Spain). All cases were confirmed by both molecular techniques and histology. The infected individuals were two Mediterranean painted frogs (Discoglossus pictus) from Girona province found in 2018 and 2020, one Iberian waterfrog (Pelophylax perezi) from Tarragona province found in 2018, and one European common frog (Rana temporaria) from Barcelona province found in 2019. This is the first time that mortality associated with this pathogen has been confirmed in D. pictus and P. perezi. The role of the fungus as an agent possibly leading to death, in association with other external environmental factors, is discussed. These findings could suggest a recent increase of the incidence of this disease in the region. Some of these cases are particularly worrying because of their occurrence close to sites where some endemic amphibian species with extremely reduced distributions inhabit.

A new chronological framework and site formation history for Cova del Gegant (Barcelona): Implications for Neanderthal and Anatomically Modern Human occupation of NE Iberian Peninsula

The chronological framework for Neanderthal occupation and demise across Europe continues to be debated. In particular, there is still uncertainty regarding the nature, timing and regional expressions of the Middle to Upper Palaeolithic transition associated with the disappearance of Neanderthals and the broader expansion of modern human populations in Europe around 42–40 thousand years ago (ka). The geographical and chronological distribution of Neanderthal populations also remains difficult to evaluate owing to the practical challenges of directly dating human fossils at many sites, and the fact that a large proportion of Neanderthals sites lie close to, or well-beyond, the limits of radiocarbon dating. Cova del Gegant – one of the few sites in north-eastern Iberian Peninsula to yield Neanderthal fossil remains, associated Mousterian archaeological layers, and occupations related to the Middle and Upper Palaeolithic transition – is a key locality for informing these ongoing debates. Here we provide a comprehensive chronological framework for the Cova del Gegant site using multiple radiometric dating techniques (uranium-thorium (U–Th), radiocarbon and luminescence dating), sedimentological and micromorphological analyses, and Bayesian modelling. This integrated chronostratigraphic approach enables us to reliably reconstruct site formation processes and history, and undertake improved correlations with other sites regionally. The results allow us to sub-divide the Cova del Gegant sequence into three sections spanning ∼94 ka to ∼32 ka, namely: a Middle Palaeolithic sequence covering ∼94–59 ka, a Châtelperronian/Aurignacian section spanning ∼43–39 ka, and a Late Aurignacian/Gravettian section spanning ∼34–32 ka. The Neanderthal fossil remains accumulated in the cave between the end of Marine Isotope Stage (MIS) 5/MIS 4 and the beginning of MIS 3, during two different events dated to ∼72–67 ka and ∼60–52 ka. The chronological framework for Cova del Gegant is in accordance with that reported for other Middle and Upper Palaeolithic sites in north-eastern Iberian Peninsula, and reveals a record of successive human occupation coinciding with a period of progressive global cooling and lowering sea levels (end of MIS 5 through to MIS 2). Sedimentological evidence points to the emergence of a coastal platform in front of the cave and indicates that local palaeoenvironmental conditions likely benefited human displacements along the littoral margin, and favoured repeated occupation of the cave during the Late Pleistocene.

Unveiling the conservation status of the sessile oak forest for their protection and management in the northeast of the Iberian Peninsula

The sessile oak forests found on the northeast of the Iberian Peninsula are ascribed to the Lathyro-Quercetumpetraeae association and play a key role in understanding the ecology of this habitat, as this region represents its xeric limit. For this reason, we analysed the biodiversity patterns and current conservation status of the sessile oak forests in the region. To do so, we collected Braun-Blanquet inventories of 34 plots randomly distributed throughout the sessile oak forests. The results showed a relationship between the climatic conditions and the biodiversity variables. While the richness of the community increased with decreasing temperatures, the characteristic species found within the community decreased at these same temperatures. This result was due to the presence of most companion species in the cool zones at high elevations.Sessile oaks are found close to other communities, such as silver birches and Scot pine forests.On the other hand, in the warm areas at low elevations, the sessile oak community was more established, with plants typical of this type of forest. These slightly warmer zones with sessile oaks are very important in terms of conservation and more vulnerable to climate change and the thermophilization of the community, as has been studied. As such, protecting and managing these forests is key to conserving this community. Nevertheless, as current protection measures do not safeguard most of these forests, it is essential to define a conservation strategy to preserve them. Using the conservation status, we have established criteria to improve the conservation strategy for sessile oak forest on the NE Iberian Peninsula.

A new species of Eomellivora from the latest Aragonian of Abocador de Can Mata (NE Iberian Peninsula)

ABSTRACT Eomellivora is a large-bodied mellivorine mustelid genus widely distributed throughout Eurasia and North America during the late Miocene (MN9-MN13). Here, we report the oldest Eurasian material of Eomellivora based on a palate and two mandibular fragments from ACM/PTA-A2, a pre-Vallesian (11.21 Ma; latest MN7+8) locality of Abocador de Can Mata (Vallès-Penedès Basin, NE Iberian Peninsula) that slightly predates the first appearance datum of Hippotherium by ~30 kyr. The described material differs from Hoplictis helbingi – another large mustelid recorded within the same basin in the roughly coeval site of Castell de Barberà (~11.2, earliest MN9) – and more closely resembles Eomellivora spp. Despite closer resemblances in both size and dental shape with the Vallesian (MN9–MN10) species Eomellivora piveteaui, the ACM material differs in possessing multiple features that may be considered plesiomorphic. A new species, Eomellivora moralesi sp. nov., is thus erected based on the described material. A cladistic analysis confirms that the new species occupies a basal-most position within the Eomellivora clade, in agreement with its older age and more plesiomorphic morphology.

Optimal selection of monitoring sites in cities for SARS-CoV-2 surveillance in sewage networks.

Selecting sampling points to monitor traces of SARS-CoV-2 in sewage at the intra-urban scale is no trivial task given the complexity of the networks and the multiple technical, economic and socio-environmental constraints involved. This paper proposes two algorithms for the automatic selection of sampling locations in sewage networks. The first algorithm, is for the optimal selection of a predefined number of sampling locations ensuring maximum coverage of inhabitants and minimum overlapping amongst selected sites (static approach). The second is for establishing a strategy of iterations of sample&analysis to identify patient zero and hot spots of COVID-19 infected inhabitants in cities (dynamic approach). The algorithms are based on graph-theory and are coupled to a greedy optimization algorithm. The usefulness of the algorithms is illustrated in the case study of Girona (NE Iberian Peninsula, 148,504 inhabitants). The results show that the algorithms are able to automatically propose locations for a given number of stations. In the case of Girona, always covering more than 60% of the manholes and with less than 3% of them overlapping amongst stations. Deploying 5, 6 or 7 stations results in more than 80% coverage in manholes and more than 85% of the inhabitants. For the dynamic sensor placement, we demonstrate that assigning infection probabilities to each manhole as a function of the number of inhabitants connected reduces the number of iterations required to detect the zero patient and the hot spot areas.

A proximal radius of Barberapithecus huerzeleri from Castell de Barberà: Implications for locomotor diversity among pliopithecoids

Pliopithecoids are a diverse group of Miocene catarrhine primates from Eurasia. Their positional behavior is still unknown, and many species are known exclusively from dentognathic remains. Here, we describe a proximal radius (IPS66267) from the late Miocene of Castell de Barberà (Vallès-Penedès Basin, NE Iberian Peninsula) that represents the first postcranial specimen of the pliopithecoid Barberapithecus huerzeleri. A body mass estimate based on the radius is compared with dental estimates, and its morphology is compared with that of extant and fossil anthropoids by qualitative means as well as by landmark-based three-dimensional geometric morphometrics. The estimated body mass of ∼5 kg for IPS66267 closely matches the dental estimates for the (female) holotype, thereby discounting an alternative attribution to the large-bodied hominoid recorded at Castell de Barberà. In multiple features (oval and moderately tilted head with a pronounced lateral lip and a restricted articular area for the capitulum; proximodistally expanded proximal radioulnar joint; and short, robust, and anteroposteriorly compressed neck), the specimen differs from hominoids and resembles instead extant nonateline monkeys and stem catarrhines. The results of the morphometric analysis further indicate that the Barberapithecus proximal radius shows closer similarities with nonsuspensory arboreal cercopithecoids and the dendropithecid Simiolus. From a locomotor viewpoint, the radius of Barberapithecus lacks most of the features functionally related to climbing and/or suspensory behaviors and displays instead a proximal radioulnar joint that would have been particularly stable under pronation. On the other hand, the Barberapithecus radius differs from other stem catarrhines in the less anteroposteriorly compressed and less tilted radial head with a deeper capitular fovea, suggesting a somewhat enhanced mobility at the elbow joint. We conclude that pronograde arboreal quadrupedalism was the main component of the locomotor repertoire of Barberapithecus but that, similar to other crouzeliids, it might have displayed better climbing abilities than pliopithecids.

Snowfall and snow cover evolution in the Eastern Pre-Pyrenees (NE Iberian Peninsula)

Snow cover has significant impacts on geoecological dynamics as well as on socio-economical systems. An accurate quantification of snow precipitation patterns in mountain regions is needed to better understand the spatio-temporal implications of snow cover. The objective of this work is to characterize the patterns of solid precipitation and snow cover in two high Mediterranean massifs. To this purpose, we analyse instrumental data series of snowfall and snow depth of Port del Comte (2316 m a.s.l.) and Cadí-Nord (2134 m). Both stations are situated in the eastern Pre-Pyrenees and include 14 consecutive snow seasons from November to May, allowing to (i) explore the dependence of the main drivers of snowpack: temperature and snowfall; (ii) find out the most frequent circulation weather types associated with high intensity snowfall events, and finally (iii) investigate the role of the North Atlantic Oceanic (NAO) teleconnection pattern explaining snow cover evolution during the winter season. Data show that snowfall is controlled by similar weather types in both stations that resulted in similar snowfall averages: 205 cm and 258 cm at Port del Comte and Cadí-Nord, respectively. Nevertheless, local factors interfere with the amount of snow depth recorded, which is moderately different between stations. Whereas Cadí-Nord records a seasonal mean of 66 cm, Port del Comte records a smaller quantity of 25 cm with a high interannual and seasonal variability. In fact, snowfall recurrence, snow amount or duration in the ground is considerably variable among years (CV>20). In these stations, snow cover duration is determined by the precipitation in the form of snow falling during the previous months. Snowfalls in moderate to severe episodes (>15 cm in 24 h) are mainly driven by Atlantic flows, mostly from NW. In addition, NAO pattern is negatively correlated with snowfall in November and December months (R>-0.50), showing a weaker and not statistically significant correlation during the rest of the winter season.

Fish size spectra are affected by nutrient concentration and relative abundance of non-native species across streams of the NE Iberian Peninsula

Aquatic ecosystems are strongly body-size structured with a decline of numerical abundance with increasing body size (hereafter, the size spectrum). Marine and lake fish studies have reported consistent variations of size spectra in relation to environmental conditions and biotic composition, but little is known about stream fishes. Accordingly, in this study we test several hypotheses about the effects of local water conditions, biotic introductions and cumulative pressures (measured as the IMPRESS index) on the fish size-spectrum slope (that is, the linear rate of decline of fish abundance as body size increase in a log-log scale) and the size-spectrum intercept (commonly used as proxy for carrying capacity) among 118 local fish assemblages in streams of the NE Iberian Peninsula. To our knowledge, this is the first time that an extensive river fish dataset is used in a dendritic network to cover systematic changes of size-spectrum parameters. We find that the slope and intercept of the fish size spectrum are negatively correlated with nutrient concentration (mainly total phosphorus), with a greater relative abundance of small fishes but a decline of overall carrying capacity. Moreover, fish assemblages with greater relative abundance of non-native species have flatter size-spectrum slopes. In contrast, the IMPRESS index and climate-related variables are poor predictors of the shape of the fish size spectra. This study contributes to better understanding of the main factors structuring fish assemblages in lotic environments of the Iberian Peninsula. We encourage more research on this line to further explore the use of fish size structure to evaluate the ecological health of riverine ecosystems.

Influence of topography on sediment dynamics and soil chemical properties in a Mediterranean forest historically affected by wildfires: NE Iberian Peninsula

Influence of topography on sediment dynamics and soil chemical properties in a Mediterranean forest historically affected by wildfires: NE Iberian Peninsula

Effects of Fire on the Organic and Chemical Properties of Soil in a Pinus halepensis Mill. Forest in Rocallaura, NE Spain

The present study was conducted following a fire that took place in Rocallaura (NE Iberian Peninsula) in 23 June 2016 with the aim of analyzing the chemical properties of soil in burnt and unburnt areas in order to determine the short-term effects of fire on an ecosystem dominated by Pinus halepensis Mill. Transects were laid out in a control area and an adjacent burnt area. Laboratory analyses were performed to determine the chemical properties of the organic and mineral soil layers at 5 cm and 10 cm (total carbon, total nitrogen, organic and inorganic carbon, carbonates, pH, electrical conductivity, and major cations). The results show partial combustion of the organic substrate, with a significant increase in TC, OC, TN, EC and K+, and a slight decrease in pH in the post-fire area compared to the control area, demonstrating that the fire was of low intensity and did not generate significant short-term negative impacts on the soil. Soils of this type, with high organic matter content, tend to maintain their structure after a low-intensity fire and retain the nutrients necessary for ecosystem recovery and resilience.