Southern Apennines Research Articles

Hydrogeochemical multi-component approach to assess fluids upwelling and mixing in shallow carbonate-evaporitic aquifers (Contursi area, southern Apennines, Italy)

With the aim of deepening our understanding of deep-seated fluids upwelling and mixing in large regional aquifers, we performed a hydrogeochemical study of twenty-two springs in the Contursi area (upper Sele river valley, southern Apennines) by means of the measurements of chemical-physical parameters, major ions, trace elements, and stable and radioactive isotopes. Besides, we realized two updated geo-structural cross-sections in order to reconstruct the groundwater flowpath in the study area. The hydrogeochemical composition, as well as the water temperature allow to identify-three main groups of groundwater: Cold and Low salinity Groundwater (CLGW), Intermediate Salinity Groundwater (ISGW), and Thermal Salinity Groundwater (TSGW). The CLGW group, mostly emerging at the boundary of carbonate aquifers, is characterized by alkaline earth-bicarbonate hydrofacies. Instead, ISGW and TSGW, situated in the inner zone of the valley, show gradually a hydrogeochemical evolution towards sodium-chloride type hydrofacies domain with the highest salinity value. Stable isotope (δ18O-δD) of CLGW reveal the local meteoric origin of groundwater, while isotopic signatures of ISGW and TSGW is associated with the deep fluids inflow. CLGW hydrogeochemistry is clearly related to dissolution of carbonate rocks. On the other hand, for ISGW and TSGW an additional contribution from evaporitic rocks is supported by saturation indices values (gypsum and anhydrite) and validated by isotopic signature of dissolved sulphate (δ34S-δ18O). The application of two models based on tritium data (i.e., the piston-flow and well-mixed reservoir) attributes longer and deeper groundwater flowpaths to TSGW. Through geothermometric calculations (e,g., K-Mg and SiO2-quartz), the equilibrium temperature of deep fluids reservoir is also extrapolated (i.e., 75–96 °C). The results of the adopted hydrogeochemical multi-component approach allowed us to propose an interpretative model of groundwater flowpath for the Contursi area, where deep-seated tectonic discontinuities play a significant role for the upwelling of saline deep thermal fluids in shallow aquifers.

Drainage integration of small endorheic basins at the Pleistocene-Holocene transition: An example from southern Italy

The drainage integration of three Late Pleistocene intramontane basins located in the southern Italian Apennines was reconstructed by integrating information derived from geomorphic, structural, and stratigraphic analyses. The Santaloja (SLJ), Lago (LG), and Pantani (PN) basins are located in the axial zone of the Apennines fold-and-thrust belt where they mainly comprise Mesozoic to Cenozoic deep-sea water siliceous and calcareous rocks. The Quaternary development of these intramontane basins draining the Basento River catchment provides an example of drainage evolution within collisional mountain belts and its tectonic and climatic controlling mechanisms. Tectonically, sets of NW-SE- and NE-SW-trending faults formed a large trough with ensuing river valley development configured to synclinal folds. The ongoing interplay of these active and passive tectonic controls lead to compartmentalisation into three endorheic basins. Uncalibrated radiocarbon dating of peat layers from boreholes reveals that lacustrine facies conditions prevailed during the Late Pleistocene, spanning 34,785 to 41,325 ka during Marine Isotope Stage 3. Morphometric analysis suggests that these endorheic lacustrine basins subsequently became integrated via overspill from 13.25 kyr calBC onwards linked to Late Pleistocene climatic changes creating the Basento River. Within the axial zone of the southern Apennines, tectonically driven headwards erosion is commonly attributed to lengthening of major rivers like the Basento River. However, this study demonstrates a more complex interplay between tectonics and climate change for intramontane basin development and its drainage evolution.

Post-lacustrine evolution of a tectonically-controlled intermontane basin: Drainage network analysis of the Mercure basin, southern Italy

Topographic analysis, drainage network morphometry, river profile analysis, and spatial distribution of fluvio-lacustrine terraces have been used to reconstruct the drainage network evolution in the Mercure River basin, a large intermontane tectonic basin of the axial zone of southern Apennines. Morphotectonic evolution of the study area is mainly controlled by poly-kinematics high-angle WNW-ESE and NE-SW faults, which promoted the development of a complex landscape with relict landscapes and/or low-relief erosional surfaces that occurred in a staircase arrangement at the top of the landscapes or at higher altitudes than the basin infill. The creation of the accommodation space for the deposition of the thick basin infill was related to an important tectonic phase of block-faulting along N120°-trending normal faults, which occurred in the final part of the Lower Pleistocene. Such an evolution strongly controls the longitudinal profile forms of channels draining the northern sector of the study area, which are featured by a well-developed concave-up segment in river profiles of these channels between an upward trait with lower values of channel steepness and the trace of the master fault. River profiles in north-western and south-east sectors of the Mercure River basin exhibit clear knickpoints at altitudes comparable with those of the superimposed orders of relict landscapes related to the initial formation of the tectonic basin and the subsequent evolution of the endorheic basin, with a post-lacustrine geomorphological evolution of the drainage network that is controlled by fluvial incision occurring at rates comparable than those reconstructed by independent morphotectonic markers. The erosion of the threshold of the endorheic basin occurring during the base-level fall of the MIS 12 promoted a dramatic base-level fall of about 150 m, which corresponds to a mean incision rate of about 0.35 mm/yr. Post-lacustrine evolution of the Mercure basin strongly controls the morphometric features of the drainage network, which preserves a centripetal pattern with several planimetric anomalies such as counterflow and high-angle confluences, local-scale fluvial capture phenomena and drainage divide migrations.

Predation of wolves on feral horses in Apennines Areas of Southern Italy: A Case Study Report

Although wolf predation on horses is generally low, it can be significant where horses are grazed extensively and there are low densities of wild prey, such as in Southern Europe. The economic damage of wolf predation on horses can have a major impact in certain situations involving free-ranging horse populations and the topic needs more attention. This is the case of Spain, Portugal and Italy where it is possible to find many examples of wolf predations on feral horses. The main factor predisposing horses to wolf pre¬dation worldwide is the free-ranging management system. In Italy special attention is given to the horses bred in a particular area of the Southern Apennines: the Pentro horses; they represent a rare endangered equine population of Molise Region with its owns genetic characterisation. The losses of horses caused by wolves predations increase exponentially from year to year. Considering the very low number of Pentro Horses, any prey represents a considerable loss from a morphological and genetical point of view. Consequently, the predation phenomena represent a considerable limit to the selection and maintenance of these horses. This is why it was decided to create a special database with the aim of monitoring, analyzing and preventing predatory phenomena and consequently to keep under control the number of predatory events by the wolf. The database was processed by collection of data concerning: when the predation take place, the age of the preyed equines, the type of injury and the parts of the body injured or removed by the wolf, the body location of the damage and the recognition and value of money compensation. The data collected evidenced how there is a need for innovative approaches to prop¬erly mitigate predation and support the traditional free-ranging husbandry system with its high ecologi¬cal and cultural value.

Assessing the Risk of Damages by Wild Boars (Sus Scrofa) in Italian Apennines. Preliminary Report

Wildlife, particularly wild ungulates, has experienced a significant demographic increase throughout Europe, especially in the last 30 years. The objective of this study was to create a preliminary impact map of wild boars (Sus scrofa) in the Molise region of the Italian Southern Apennines, and their correlation with road accidents. A GIS software was used to process a map, and the impact of wild boars was categorized based on land use. An analysis of the environmental characteristics of the neighboring raster was conducted, considering the presence of roads, particularly with respect to accident events. The georeferenced damages were superimposed onto the impact risk map. The geo-referenced damages caused by wild boars indicate that they are primarily concentrated in areas where road accidents have occurred and where there is a high risk of impact. These maps serve as a valuable starting point for managing wild boars in the region by optimizing strategies from technical and economic perspectives. This process must include population control by evaluating the Annual Useful Increase index (IUA), based on processes related to birth-immigration and mortality-emigration of the species.

A new Hoplia Illiger, 1803 from Calabria, southern Italy (Coleoptera: Scarabaeidae: Melolonthinae: Hopliini)

Hoplia asprumuntiana Patacchiola, Fabbriciani, Boschin & Biscaccianti, new species from Aspromonte National Park (Calabria, southern Italy) is described and illustrated. The new species is compared with the two apparently most closely related species, namely H. maremmana Leo, Liberto, Rattu & Sechi, 2010 and H. meridiana Uliana, Liberto & Leo, 2017. The differences between H. asprumuntiana new species and the other Hoplia Illiger, 1803 occurring in the southern Apennine are also discussed, chiefly regarding H. paganettii Müller, 1907 described from Aspromonte. Some remarks on ecology and phenology of adults are also reported.

Comparing and integrating artificial intelligence and similarity search detection techniques: application to seismic sequences in Southern Italy

SUMMARYUnderstanding mechanical processes occurring on faults requires detailed information on the microseismicity that can be enhanced today by advanced techniques for earthquake detection. This problem is challenging when the seismicity rate is low and most of the earthquakes occur at depth. In this study, we compare three detection techniques, the autocorrelation FAST, the machine learning EQTransformer, and the template matching EQCorrScan, to assess their ability to improve catalogues associated with seismic sequences in the normal fault system of Southern Apennines (Italy) using data from the Irpinia Near Fault Observatory (INFO). We found that the integration of the machine learning and template matching detectors, the former providing templates for the cross-correlation, largely outperforms techniques based on autocorrelation and machine learning alone, featuring an enrichment of the automatic and manual catalogues of factors 21 and 7, respectively. Since output catalogues can be polluted by many false positives, we applied refined event selection based on the cumulative distribution of their similarity level. We can thus clean up the detection lists and analyse final subsets dominated by real events. The magnitude of completeness decreases by more than one unit compared to the reference value for the network. We report b-values associated with sequences smaller than the average, likely corresponding to larger differential stresses than for the background seismicity of the area. For all the analysed sequences, we found that main events are anticipated by foreshocks, indicating a possible preparation process for main shocks at subkilometric scales.

Geoheritage Management in Areas with Multicultural Interest Contexts

Sites of geo-cultural interest are often included in areas where multicultural contexts (geo and non geo) are present. Cultural heritage dissemination is sometimes mono-contextual, paying little attention to the possibility of inclusion in a wider multicultural context. When these different contexts are linkable to each other following a specific theme, multicultural heritage dissemination will be possible, and often the geo context can represent a fulcrum, a resilient tool in doing that. A portion of the Sinni river’s catchment area (Basilicata region, Southern Italy) has been chosen to test and verify the multi-level/disciplinary approach applicability. The area is located on the southeastern edge of the Pliocene to Pleistocene Sant’Arcangelo basin in the Southern Apennines chain of Italy. Here, both basic observations on the physical geography landscape evolution and specialized observations on river dynamics and on the hydrographic network have been carried out. Educational routes will be proposed with different educational levels along a path that will include the San Giorgio Lucano hypogea. This paper represents the results of a qualitative study providing an overview of the possibility, in a multicultural context, about whether, when, and how the geo context may act as a link between the different disciplines and what is the best way to make it. A relational database, organized in contexts, areas, and themes, is planned at different levels of detail, and is currently being developed in order to make final products easily available. Each level will be provided with basic concepts, territorial contextualization, and of activities/itineraries. The goal is to provide a versatile tool that enhances the territorial multi-cultural heritage to reach a greater number of end users interested in both geo and non geo contexts.

Insights on the active Southern Matese Fault system through geological, geochemical, and geophysical investigations of the CO2 gas vent in the Solopaca area (southern Apennines, Italy)

The south-eastern sector of the Matese Massif (southern Apennines, Italy) includes several nonvolcanic gas (mainly CO2) vents. The gas emissions in the northern part (Ciorlano-Ailano sector) have been associated with the Southern Matese Fault system, whereas a similar relationship is not evident in the southern part (Telese-Solopaca sector). Hence, we investigated the latter area (hills north of Solopaca town) through a multidisciplinary study of the principal CO2-degassing vent (Santantuono spring). The main goal is to reconstruct the structural architecture of the area and study the role of the fault array in conveying the gas migration to the surface. In particular, an integrated approach that combines structural and stratigraphic investigations with CO2 flux and geoelectrical surveys is proposed to shed light on the relationships between near-surface faults and gas rising. The main results from the geological-structural investigation suggest that thrust faults are the oldest structures, mainly verging to NNW, crosscut by high-angle N-S and younger NW-SE normal faults. This understanding is supported by the results of the CO2 flux survey, which records the highest flux values in correspondence with the mapped young normal faults, especially at their intersections. Moreover, the hypothesized tectonic and stratigraphic structure at depth is entirely consistent with the 3D geoelectrical model of the survey area provided by a 3D electrical resistivity tomography investigation, which also identifies the main NW-SE striking fault as the preferential pathway for gas migration. Finally, we suggest that the reconstructed NW-SE faults are the prolongation of the active Southern Matese Fault system bounding the SW Matese Massif margin defined by different segments with dominant normal kinematics and several gas vents.

Spatio-temporal evolution of ground motion intensity caused by reservoir-induced seismicity at the Pertusillo artificial lake (southern Italy)

We investigate the spatiotemporal evolution of ground motion caused by reservoir-induced seismicity at the Pertusillo artificial lake in southern Italy. The area has a strong seismogenic potential, having been affected in the past by the 1857, Mw 7.0 Basilicata earthquake. We consider ∼1,000 microearthquakes that occurred from 2001 to 2018 and were recorded by a local network of nine seismic stations. The ground motion intensity associated with microseismicity allows us to identify two periods, each lasting approximately 2 years. They are characterized by a high rate of events but exhibit different source properties and spatial distributions. In the first period, the seismicity is spatially clustered close to the lake, on faults with different orientations and kinematics. In the second period, the seismicity is distributed along the Monti della Maddalena faults. Comparing the ground motion intensities of the two periods, we observe that events that occurred in the first period are associated with higher stress levels than others, in agreement with the b-values of the respective frequency-magnitude distributions. We compare the temporal evolution of the ground motion intensity with the rainfall and water levels measured at the artificial lake, as well as with the discharge of a ∼80 km distant spring, which is strictly controlled by climate trends. The results provide information about the regional processes acting on the southern Apennines. Our results show that the microseismicity is clearly associated with the Pertusillo artificial lake in the first period, whereas in the second period is a result of a combination of local effects due to water table oscillations of the lake itself, regional tectonics, and the poroelastic and elastic phenomena associated with carbonate rocks hosting aquifers.

Addressing conservation measures through fine-tuned species distribution models for an Italian endangered endemic anuran

Climate and land cover changes are the two most important stressors causing the decline of amphibians’ populations worldwide. Within the Mediterranean area, one of the global biodiversity hotspots, the endemic Italian yellow-bellied toad ( Bombina pachypus ) suffered the same fate, as the decreases and local extinctions proved over time. Since the need to preserve this Apennine endemic species is evident, we take advantage of a novel approach combining climate-based ecological niche models and post-modelling GIS techniques (i.e., the weighted overlay framework) to produce finer species distribution models for B. pachypus . In doing so, we coupled climate variables with topographic-, hydrologic-, and habitat-related predictors, sharpening the potential species’ distribution at its whole range scale. Our findings show a latitudinal subdivision in predicted suitability: Central Apennines populations are expected to suffer more than the Northern ones, with considerable potential future losses of genetic diversity. On the contrary, Southern Apennines’ suitability is predicted to remain stable over time, preserving the vast diversity. When assessing the coverage that protected areas offer to the locations of suitable habitats for B. pachypus , the protected sites of the Central Apennines result in slightly less suitable conservation areas than those in the Northern and Southern Apennines. The overall protected areas coverage is currently low (∼20%) and predicted in the future to narrow towards medium suitability values, except in Southern Apennines, where an increase is inferred. In light of our spatially-explicit results, we suggest that a national-scale conservation strategy should consider different management options according to the sub-territories that our analyses highlighted. Our coupled “weighted modelling – spatialised genetic inference” approach permits us to support different conservation policies at all spatial scales, capitalising on relatively few input data. Also, in-depth spatial analyses should be performed to support effective protection strategies and management for the conservation stakeholders. • Fine-tuned SDMs deepen knowledge and strongly uphold Bombina pachypus conservation. • Changes will differently affect biogeographic sectors’ suitability for B. pachypus. • Protected areas’ policy should base on predicted local responses to future changes.

Landslides and predisposing factors of the Southern Apennines, Italy

ABSTRACT The Fiumarella di Corleto drainage basin is an emblematic sector of the southern Apennine thrust belt in the Basilicata region (Southern Italy), which is strongly affected by landslides. Landslides both affect the urban area and the facilities related to hydrocarbon exploitation, such as the pipelines and oil wells connected with the oil centre located just outside the eastern border of the study area. Based on a detailed field survey, supported by stereoscopic analysis, a landslide inventory map has been realized, which also reports the associated processes and landforms. The relationships between the different types of landslides and the various predisposing factors like outcropping lithologies, slopes steepness, slope exposition and land use have been also investigated. The acquired data relate to a geologically complex area of the southern Apennines subject to recent uplift and represent a fundamental contribution useful for the correct management of the territory.

Late Quaternary sedimentary record of estuarine incised-valley filling and interfluve flooding: The Manfredonia paleovalley system (southern Italy)

Multiple paleovalley systems of late Quaternary age have been widely explored in previous research from the Gulf of Manfredonia on the basis of seismic data, but only limited information is available on their proximal (onshore) segments. Through an integration of sedimentary, paleoecological (mollusks, benthic foraminifers, ostracods), and geochemical analyses from three 30-50 m-long onshore cores and a sequence-stratigraphic framework chronologically constrained by 25 radiocarbon data, we document the stratigraphic architecture of three contiguous paleovalley systems (Candelaro, Cervaro and Carapelle rivers) and their sedimentary response to Late Pleistocene valley excavation, Holocene filling and basinwide interfluve flooding. Above a prominent sequence boundary formed during the Late Pleistocene relative sea-level fall, fluvial-channel gravels and sands (lowstand systems tract) are overlain by a deepening-upward, valley-fill succession of inner-estuarine (freshwater) to outer-estuarine (brackish) muds (lower transgressive systems tract – TST). The individual valley fills are overlain by laterally extensive bay deposits (upper TST) and by a progradational succession of prodelta/delta front and offshore/shoreface deposits that reflect normal regression under highstand conditions (HST). The transition from fluvial to inner-estuary (fluvial-dominated) and outer-estuary (wave-influenced) deposits records the progressive shift in sediment provenance from Southern Apennine source rocks to a mixed composition that reflects increasing alongshore sediment contribution from northern sources via the SE-directed Western Adriatic Current. The stratigraphic surface that demarcates the transition from estuarine to bay depositional systems (lower/upper TST boundary) represents the physical prolongation of interfluvial terrace surfaces, as valley margins were flooded during the Early Holocene transgression. This surface, typically recognizable on seismic profiles at the boundary between low-amplitude and overlying high-amplitude reflectors, has no obvious lithologic signature in core. However, it can be readily identified on the basis of paleoecologic features (sharp increase in species diversity and in the proportion of marine taxa) that reveal the abrupt transition from laterally confined to unconfined settings.

Geosite Assessment as a Tool for the Promotion and Conservation of Irpinia Landscape Geoheritage (Southern Italy)

Irpinia (Province of Avellino, Campania Region) is a historical–geographical region of Southern Italy inhabited in pre-Roman times by the ancient Samnite tribe of the Irpini, from which the name originates. This area is characterized by both low population density and high naturalness; located on the axial sector of the southern Apennine orogenic chain, the area possesses a complex hilly and mountainous orography, with predominantly agricultural and forest land uses. In this geographical context, there are many relevant geological/geomorphological sites, witnessing a wide geodiversity attributable to complex geological evolution and relief morphogenesis. The extensive bio-geodiversity has thus led to widespread geotourism practices. Irpinia is favored for its beautiful landscapes, rich cultural heritage, and typical small towns, often enhanced by quality certifications; moreover, geotourism activities are often associated with other forms of sustainable tourism. Starting from this geographical framework, the article analyzes eight attractive geosites that represent the geotouristic value of the entire Irpinia area well. The analysis was conducted using well-known qualitative and quantitative assessment methods. The results obtained, emphasizing the salient aspects of geodiversity, can be used in planning the usability of the sites and, more generally, planning for the Irpinian landscape in a geo-ecotouristic sense.

Depositional record of confined turbidites in syn-subduction intraslope basin: insight from the Tufiti di Tusa Formation (Southern Apennines, Italy)

A detailed lithostratigraphy and facies analysis of a type section of the Tufiti di Tusa Formation, including deep-marine clastic successions with syn-orogenic volcanic detritus and deposited in the late Eocene - early Miocene basin system at the front of the growing Maghrebian - Southern Apennines orogen, is discussed in the paper. Based on facies analysis and composition, the study section was subdivided into the following units, from bottom to top: Unit I, mostly formed by contained-reflected beds (including a bed similar to the Contessa megabed of the Marnoso-arenacea Formation in the Northern Apennines), with the ratio of sandstone intervals to mudstone intervals (S/M) of 0.6 and with mostly-calciclastic sandstone to siltstone fraction; Unit II, recording a moderate decrease in contained-reflected beds and a moderate increase in slurry beds, with S/M ratio of 0.9, and with mostly-siliciclastic sandstone to siltstone fraction; Unit III, recording a further decrease in contained-reflected beds and an evident increase in slurry beds and very-thick beds with a basal massive very coarse to coarse-grained sandstone, with S/M ratio of 2.5, and with mostly-volcaniclastic sandstone to siltstone fraction.In accordance with the depositional models for the infill of confined turbidite basins, Units I and II are here interpreted as representing a flow ponding depositional phase, while Unit III as iconic of a flow stripping depositional phase. The compositional variation from Unit I to Unit II records cutoff of calciclastic supply from underplate sources, possibly tied to tectonic uplift of the external basin margin; while that from Unit II to Unit III records sudden availability of volcaniclastic sediment possible due to burial of morphological high(s) between the internal volcanic arc (source of the volcaniclastic sediment) and the depositional basin, and/or establishment of tectonically-controlled conduits cutting the above high(s). This study may improve the knowledge not only of infilling evolution of confined turbidite basins, but also of the depositional setting of the late Paleogene Southern Apennines subduction margin in the Central Mediterranean.

A simplified procedure to assess the effects of climate change on landslide hazard in a small area of the Southern Apennines in Italy

A simplified procedure to assess the effects of climate change on landslide hazard in a small area of the Southern Apennines in Italy

An Investigation into the Water Retention Behaviour of an Unsaturated Natural Fissured Clay

The presence of intensely fissured soils is often found to relate to high geotechnical risks, such as landslide risk. This is especially the case of the Southern Apennines, Italy, where slopes formed of intensely fissured clays are frequently affected by landslides. The latter are generally triggered by rainfall infiltration, which takes place through the outcropping, unsaturated clayey soil cover. With the final aim of reducing landslide risk in areas covered by fissured clays, a detailed hydro-mechanical characterisation of these materials is required. While the behaviour of fully saturated fissured clays has been investigated in the last decade, only a few studies dealing with unsaturated, natural fissured clays are reported in the literature. The present paper aims to give a contribution toward filling this gap by extending an investigation campaign started a few years ago on the Paola Doce fissured clay outcropping on the Pisciolo slope (Southern Apennines, Italy). The physical properties of the material and some of its key micro- to meso-structural features are first analysed, the latter also based on Scanning Electron Microscope (SEM) micrographs of an undisturbed sample taken at 1.4 m depth on the Pisciolo slope, which is mainly formed of Paola Doce clay. Subsequently, water retention data of the soil are presented, which were obtained using both high-capacity tensiometers and the filter paper technique. These data were collected not only on undisturbed samples but also while subjecting the same material to drying paths. The results herein reported aim to make a link between the water retention behaviour of the Paola Doce clay sampled at Pisciolo and its fissured structure.

Phylogeographic structure of common sage (Salvia officinalis L.) reveals microrefugia throughout the Balkans and colonizations of the Apennines

Studying the population-genetic and phylogeographic structures of a representative species of a particular geographical region can not only provide us with information regarding its evolutionary history, but also improve our understanding of the evolutionary processes underlying the patterns of species diversity in that area. By analysing eight highly polymorphic microsatellite loci and two chloroplast DNA regions, we have investigated the influence of Pleistocene climate fluctuations on the evolutionary history of Salvia officinalis L. (common sage). The populations with the highest genetic diversity were located in the central parts of the Balkan distribution range. A large group of closely related haplotypes was distributed throughout the Balkans and the central Apennines, while the private lineage occupied the southern Apennines. In addition, two highly differentiated lineages were scattered only over the Balkans. The results suggest that a single refugium of the studied species from the last glacial period was located in the central part of the range in the Balkans. Numerous microrefugia, probably spanning several glaciation cycles, were scattered across the Balkans, while colonisation of the Apennines from the Balkans occurred at least on two occasions.

Clonality drives structural patterns and shapes the community assemblage of the Mediterranean Fagus sylvatica subalpine belt.

Past anthropogenic disturbances lowered the altitudinal distribution of the Mediterranean Fagus sylvatica forests below 2,000 m a.s.l. Accordingly, our current understanding of the southern distribution range of F. sylvatica forests is restricted to managed stands below this elevation, neglecting relic forests growing above. This study has shed light on the structure and species assemblage of an unmanaged relict subalpine F. sylvatica stand growing within the core of its southernmost glacial refugia and at its highest species range elevation limit (2,140 m a.s.l.) in southern Apennines (Italy). Here, tree biometric attributes and understory species abundances were assessed in eight permanent plots systematically positioned from 1,650 to 2,130 m a.s.l. In the subalpine belt, F. sylvatica had formed a dense clonal stem population that was layered downward on the steepest slopes. The density and spatial aggregation of the stems were increased, while their stature and crown size were decreased. Above 2,000 m, changes in tree growth patterns, from upright single-stemmed to procumbent multi-stemmed, and canopy layer architecture, with crowns packed and closer to the floor, were allowed for the persistence of understory herbaceous species of biogeographic interest. Clonal layering represents an adaptive regeneration strategy for the subalpine belt environmental constraints not previously recognized in managed Mediterranean F. sylvatica forests. The clonal structure and unique species assemblage of this relic forest highlight the value of its inclusion in the priority areas networks, representing a long-term management strategy of emblematic glacial and microclimatic refugia.

New SKS splitting anisotropy measurements point to tearing beneath Central Italy

In the middle of the Mediterranean, the partly still active Apennines subduction system has been usually defined using tomographic images and available shear wave splitting measurements. In this paper we describe the new seismic anisotropy dataset for Central Italy, the region where the transition between Northern and Southern Apennines occurs. The new measurements show NW-SE fast polarisation directions beneath the belt, due to the retreat of the slab, NNE-SSW orientations from proper Adriatic mantle sources, and E-W directed anisotropy, attributed to mantle convection flow at the Thyrranian side. Additionally, the new data suggest the presence of a toroidal mantle flow through a tear in the Apenninic slab, from the Adria to the Tyrrhenian side. However, mantle circulation and flows, identified by the pattern of shear wave splitting results, seem different from what was proposed in previous geodynamic models. Indeed, our results support the presence of a vertical slab tear with limited dimension. In the geodynamic model we propose, the tear acts to accommodate a differential slab retreat. The slab partitioning results in a different pattern and strength of seismic anisotropy traced from the Central Apennines with respect to the adjacent Northern and Southern Apennines.