Southwestern Alps Research Articles

Deciphering large-scale superposed fold systems at shallow crustal levels in collision zones: insights from the Marguareis Massif (southwestern Alps)

ABSTRACT We present and discuss the results of a field-based approach including accurate geological mapping and micro- to map-scale structural analysis to highlight the finite strain pattern recorded in Marguareis Unit, a massif deformed at shallow crustal levels at the boundary between Maritime and Ligurian Alps. We describe superposed tectonic structures developed under low-grade metamorphic conditions during the Alpine collision and nowadays exceptionally well recorded in the area of interest. We demonstrate that the structural frame of the Marguareis Unit results from superposition of fourfold systems, later segmented, but without significant displacements, by brittle faults.

Explaining recent trends in extreme precipitation in the Southwestern Alps by changes in atmospheric influences

This article analyzes recent trends in extreme precipitation in the Southwestern Alps and compares these trends to changes in the occurrence of the atmospheric influences generating extremes. We consider a high-resolution precipitation dataset of 1 × 1 km2 for the period 1958–2017. A robust method of trend estimation in extreme precipitation is considered, based on nonstationary extreme value distribution and a homogeneous neighborhood approach. The results show contrasting trends in extreme precipitation depending on the season. In autumn, most of Southern France shows significant increasing trends, with increase in the 20-year return level between 1958 and 2017 as large as its average value over the period, while the Northern French Alps and the Swiss Valais show decreasing extremes. In winter, significant increasing extremes are found in the valleys and medium mountain areas surrounding the Northern French Alps, while the inner French Alps, the Swiss Valais and the Aosta Valley show significant decreasing trends. In the other seasons, the significant trends are mostly negative in the Mediterranean area. Comparing these trends to changes in the occurrence of the atmospheric influences generating extremes shows that part of the significant changes in extremes can be explained by changes in the dominant influences, in particular in the Mediterranean influenced region that shows the most organized trends. In particular, the strong positive trends in extreme precipitation in autumn in Southern France are concomitant with an increase in Mediterranean influence generating extremes.

The Alps-Apennines Interference Zone: A Perspective from the Maritime and Western Ligurian Alps

In SW Piemonte the Western Alps arc ends off in a narrow, E-W trending zone, where some geological domains of the Alps converged. Based on a critical review of available data, integrated with new field data, it is concluded that the southern termination of Western Alps recorded the Oligocene-Miocene activity of a regional transfer zone (southwestern Alps Transfer, SWAT) already postulated in the literature, which should have allowed, since early Oligocene, the westward indentation of Adria, while the regional shortening of SW Alps and tectonic transport toward the SSW (Dauphinois foreland) was continuing. This transfer zone corresponds to a system of deformation units and km-scale shear zones (Gardetta-Viozene Zone, GVZ). The GVZ/SWAT developed externally to the Penninic Front (PF), here corresponding to the Internal Briançonnais Front (IBF), which separates the Internal Briançonnais domain, affected by major tectono-metamorphic transformations, from the External Briançonnais, subjected only to anchizonal metamorphic conditions. The postcollisional evolution of the SW Alps axial belt units was recorded by the Oligocene to Miocene inner syn-orogenic basin (Tertiary Piemonte Basin, TPB), which rests also on the Ligurian units stacked within the adjoining Apennines belt in southern Piemonte. The TPB successions were controlled by transpressive faults propagating (to E and NE) from the previously formed Alpine belt, as well as by the Apennine thrusts that were progressively stacking the Ligurian units, resting on the subducting Adriatic continental margin, with the TPB units themselves. This allows correlation between Alps and Apennines kinematics, in terms of age of the main geologic events, interference between the main structural systems and tectonic control exerted by both tectonic belts on the same syn-orogenic basin.

Spatial and temporal dynamics of wild boars Sus scrofa hunted in Alpine environment

This study evaluated the trend and spatial distribution of wild boar population harvested in the Alpine hunting district C.A. CN1 (Piedmont, Italy) from 1996 to 2018, and its relation with hunting effort. Protected areas were found to shape the distribution of the harvested wild boars, which decreased in number as the distance from those zones increased. The hunting bag data presented large yearly fluctuation, with a trend in line with the hunting effort until 2007 when the maximum capacity of the population to cope with the hunting pressure was reached. The variation of reproductive parameters (percentage of piglets in the hunted population and piglets to sexually matured female ratio) showed a decreasing trend in both time series. Conversely, hunting effort increased over the years, with significant trend changes in 2000 and 2015, probably associated with the increased preference for hunting activity on wild boars, and the parallel reduction of the extension of hunting areas. Predation, hunting activity, and environment could have modulated the wild boar population dynamics in the study area. Decrease in chestnut Castanea sativa production, due to the gall wasp Dryocosmus kuriphilus Yasumatsu, were reported during the period of study. This might be the main factor determining the downtrend of piglets in 2003. In addition, predation by wolves Canis lupus, whose population has sharply increased in the southwestern Alps in the last decades, might have contributed to the decline since 2010. This work outlines the importance of a proper management of protected areas, which influence the density and distribution of wild boars. In this context, hunting bags analysis is of pivotal importance to monitor population dynamics and develop proper wildlife policies.

Summer observations of Eleonora’s Falcon (<em>Falco eleonorae</em>) in the Stura Valley (South Western Alps)

From 1999 to 2020 the Eleonora’s Falcon (Falco eleonorae) has been observed 12 times at the site of Madonna del Pino, near Demonte (Province of Cuneo - Piedmont - South Western Alps). All of these individuals were birds in their second calendar year and thus these sightings are to be attributed to summer movements of nonbreeding animals. The growing number of observations of this species is imputable to the increasing identification skills of birdwatchers, necessary in order to distinguish Eleonora’s Falcons from the similar and very common Eurasian Hobby (Falco subbuteo), and to the constant monitoring of migrating raptors as part of the Migrans Project.

Decomposition in Mixed Beech Forests in the South-Western Alps Under Severe Summer Drought

Climate and plant litter diversity are major determinants of carbon (C) and nitrogen (N) cycling rates during decomposition. Yet, how these processes will be modified with combined changes in climate and biodiversity is poorly understood. With a multisite field experiment, we studied the interactive effects of reinforced and prolonged summer drought (using rainout shelters) and tree species mixing on leaf litter decomposition in beech forests in the French Alps. Forests included monospecific stands of Fagus sylvatica, Abies alba and Quercus pubescens and two-species mixtures composed of beech and one of the other species. We hypothesized (1) slower C and N release during decomposition in response to experimentally prolonged summer drought, but (2) less so in mixed compared to monospecific tree stands, due to indirect canopy effects and direct litter mixing effects. Litter lost 35% of initial C and 15% of N on average across all sites and litter types over 30 months of decomposition. The experimentally prolonged summer drought led to weakly slower C loss but had no effect on N loss. Tree species mixing did not alter drought effects on decomposition but had non-additive effects on C and N loss, which were dominated by direct litter mixing rather than indirect plot-specific tree species composition effects. Our data suggest relatively small effects of reinforced and prolonged summer drought on decomposition, possibly because process rates are generally slow during summer and because microsite variability is larger than the effects of rainfall exclusion. The dominant contribution of litter mixing to the overall effect of plot-specific tree species mixtures on decomposition supports the importance of microsite conditions for C and N dynamics during decomposition, which should be accounted for more explicitly in climate and biodiversity change predictions.

Retreating winter and strengthening autumn Mediterranean influence on extreme precipitation in the Southwestern Alps over the last 60 years

This article analyzes the large-scale circulations producing daily precipitation extremes in the Southwestern Alps and their trends from 1958 to 2017. We consider a high-resolution precipitation data set of 1 × 1 km2 and the weather patterns associated to the precipitation seasonal maxima at each grid point. The high-resolution allows us to analyze in details the atmospheric influences triggering seasonal maxima. Four influences are considered—the Atlantic influence, the Mediterranean influence, the northeast circulation and the Anticyclonic situation. We show that influences on maxima are very well organized in space but their organization depends on the season. Maxima are very mainly triggered by two types of influences in the region—the Atlantic influence and the Mediterranean influence. Trends in weather patterns producing maxima are also organized in space, with opposite trends for the Atlantic and the Mediterranean influences. The Mediterranean influence retreated very significantly over the period in winter and spring, while the Atlantic influence significantly extended further south. In autumn the Mediterranean influence strengthened where it was already dominant.

Interplay of fluvial incision and rockfalls in shaping periglacial mountain gorges

Fluvial incision is the consequence of landscape readjustment to combined tectonic and climatic processes. In the southwestern Alps (Haute Provence Geopark), deep gorges incised by the Bès River attest of efficient erosional processes at the front of the Alpine mountain range. This catchment stands in a peripheral Alpine position, out of the glaciated domain during the last glacial periods, which makes it suitable to quantify fluvial incision and related erosional processes in a glacier-free environment. In this paper, we combine high resolution 3D topographic mapping and in situ produced cosmogenic 36Cl dating of a mountain gorge (the “Clue de Barles” Gorge). First, the very high-resolution 3D topographic modeling from aerial and drone surveys permits to map the erosion markers on the gorge walls and to accurately determine the topographic shielding factor for Cosmic Ray Exposure (CRE) dating. Secondly, 36Cl CRE age distribution highlights two distinct geomorphic domains along the vertical profile: i) the higher section is characterized by clusters of similar CRE ages, interpreted as related to paraglacial rockfall events; ii) the lower section shows increasing ages with height, which are ascribed to fluvial incision occurring at a rate of 0.15 mm/yr since 25 ka, and of 2 mm/yr since 2 ka. Our results for the Clue de Barles, compared to other sites in the South French Alps highlight that: i) the gorge morphology is the result of the combination of both vertical fluvial incision and lateral gravitational processes, ii) the mean Quaternary fluvial incision rate in the Bès River catchment is at least twice lower than further east in the formerly glaciated Alps.

Structural relationships between Helminthoid Flysch and Briançonnais Units in the Marguareis Massif: A key for deciphering the finite strain pattern in the external southwestern Alps

The structural setting and tectonic evolution of the Marguareis Massif (located at the boundary between the Maritime and Ligurian Alps) has long been matter of debate. After new meso‐ and micro‐structural studies and field investigations, the tectonic unit interplay outlines a finite structural architecture more complex than that proposed in previous interpretations. We depict a stack of Briançonnais Units stemming from the Europe continental margin, and the Helminthoid Flysch Unit, detached from its original basement whose original palaeogeographic domain is still a matter of debate. Our results highlight for the first time that each unit recorded different pre‐stacking folding events progressively developed at different structural levels. The events occurred during the stacking of the units produced shear zones with top‐to‐SW sense of movement. After the syn‐stacking tectonics achieved during the Late Eocene‐Early Oligocene collisional events, the whole stack recorded the same post‐stacking deformation history here represented by a fold system with sub‐horizontal axial planes and faults. Similar tectonic evolution was documented in other sectors of the Western Alps by previous authors.

The role of the south-western Alps as a unidirectional corridor for Mediterranean brown trout (Salmo truttacomplex) lineages

AbstractThe role of the south-western Alps as a corridor for Mediterranean trout (Salmo trutta complex Linnaeus, 1758) was evaluated in order to understand the influence of the last glacial events in shaping the spatial distribution of the genetic diversity of this salmonid. For this, the allochthonous hypothesis of a man-mediated French origin (19th century) of the Mediterranean trout inhabiting the Po tributaries in the Italian side of the south-western Alps was tested. A total of 412 individuals were analysed at the mitochondrial control region. The phylogenetic classification was carried out by using a Median-Joining Network analysis. Mismatch pair-wise analysis, molecular dating and Kernel density distribution analysis of the main mitochondrial lineages were evaluated to compare past demographic dynamics with the current spatial distribution of genetic diversity. The main outcomes resulted strongly in agreement with a biogeographic scenario where the south-western Alps acted as a unidirectional corridor that permitted the colonization of the upper Durance (Rhône River basin) by trout from the Po River basin. Therefore, the Mediterranean trout should be considered as native also along the Italian side of the south-western Alps and the allochthonous hypothesis should be rejected.

Glacier Ice Thickness Estimation and Future Lake Formation in Swiss Southwestern Alps—The Upper Rhône Catchment: A VOLTA Application

Glacial lake formations are currently being observed in the majority of glacierized mountains in the world. Given the ongoing climate change and population increase, studying glacier ice thickness and bed topography is a necessity for understanding the erosive power of glacier activity in the past and lake formation in the future. This study uses the available information to predict potential sites for future lake formation in the Upper Rhône catchment located in the Southwestern Swiss Alps. The study integrates the latest available glacier outlines and high-quality digital elevation models (DEMs) into the Volume and Topography Automation (VOLTA) model to estimate ice thickness within the extent of the glaciers. Unlike the previous ice thickness models, VOLTA calculates ice thickness distribution based on automatically-derived centerlines, while optimizing the model by including the valley side drag parameter in the force equation. In this study, a total ice volume of 37.17 ± 12.26 km3 (1σ) was estimated for the Upper Rhône catchment. The comparison of VOLTA performance indicates a stronger relationship between measured and predicted bedrock, confirming the less variability in VOLTA’s results (r2 ≈ 0.92) than Glacier Bed Topography (GlabTop) (r2 ≈ 0.82). Overall, the mean percentage of ice thickness error for all measured profiles in the Upper Rhône catchment is around ±22%, of which 28 out of 42 glaciers are underestimated. By incorporating the vertical accuracy of free-ice DEM, we could identify 171 overdeepenings. Among them, 100 sites have a high potential for future lake formation based on four morphological criteria. The visual evaluation of deglaciated areas also supports the robustness of the presented methodology, as 11 water bodies were already formed within the predicted overdeepenings. In the wake of changing global climate, such results highlight the importance of combined datasets and parameters for projecting the future glacial landscapes. The timely information on future glacial lake formation can equip planners with essential knowledge, not only for managing water resources and hazards, but also for understanding glacier dynamics, catchment ecology, and landscape evolution of high-mountain regions.

Climate change and the future of endemic flora in the South Western Alps: relationships between niche properties and extinction risk

Climate change seriously threatens biodiversity, particularly in mountain ecosystems. However, studies on climate change effects rarely consider endemic species and their niche properties. Using species distribution models, we assessed the impact of climate change on the endemic flora of the richest centre of endemism in the Alps: the South-Western Alps. We projected the potential distributions of 100 taxa under both an optimistic (RCP2.6) and a pessimistic (RCP8.5) climate scenario, analysing the relationships between range dynamics and several predictors (dispersal abilities, vegetation belts, niche marginality, niche breadth, altitudinal range and present range). The negative impact ranged from weak to severe according to the scenario, but the extinction risk was low. The dispersal abilities of species strongly affected these range dynamics. Colline and subalpine species were the most threatened and the relationship between range dynamics and predictors varied among vegetation belts. Our results suggest that the rough topography of the SW Alps will probably buffer the climate change effects on endemics, especially if climate will remain within the limits already experienced by species during the Holocene. The presence of the Mediterranean-mountain flora, less affected by climate change than the alpine one, may explain the lower number of species threatened by extinction in the SW Alps than in other European mountains. These results suggest that the relationship between plants’ sensitivity to climate change, and both niche properties and vegetation belts, depends on the difference between the current climate in which species grow and the future climate, and not just on their niche breadth.

Integrating Multiple Lines of Evidence to Explore Intraspecific Variability in a Rare Endemic Alpine Plant and Implications for Its Conservation.

We studied the ecology, distribution, and phylogeography of Tephroseris balbisiana, a rare plant whose range is centered to the South-Western Alps. Our aim was to assess the extent of intraspecific variability within the nominal species and the conservation status of isolated populations. We studied genetic diversity across the whole species range. We analyzed leaf traits, which are distinctive morphological characters within the Tephroseris genus. A clear pattern of genetic variation was found among populations of T. balbisiana, which clustered according to their geographic position. On the contrary, there was a strong overlap in the morphological space of individuals across the species’ range, with few peripheral populations diverging in their leaf morphology. Studying habitat suitability by means of species distribution models, we observed that T. balbisiana range is primarily explained by solar radiation and precipitation seasonality. Environmental requirements could explain the genetic and morphological uniformity of T. balbisiana in its core distribution area and justify genetic, morphological, and ecological divergences found among the isolated populations of the Apennines. Our findings emphasize the need to account for the whole diversity of a species, comprising peripheral populations, in order to better estimate its status and to prioritize areas for its conservation.

Megacraspedus cottiensis sp. nov. (Lepidoptera, Gelechiidae) from northern Italy - a case of taxonomic confusion.

Megacraspedus cottiensissp. nov. is described from the western Alps (prov. Torino, Italy). The dorsal habitus and genitalia for both the male and brachypterous female are provided. The new species belongs to the M. faunierensis species group based on genitalia morphology and DNA barcodes, and was hitherto confused with M. neli Huemer & Karsholt, 2018 from the southwestern Alps. However, it clearly differs in morphology and DNA barcode sequences from that species and from M. faunierensis Huemer & Karsholt, 2018. The new species is suspected of being a regional endemic of the Cottian Alps.

Variscan eclogites from the Argentera–Mercantour Massif (External Crystalline Massifs, SW Alps): a dismembered cryptic suture zone

We document structural, geochemical, petrological and 40Ar/39Ar geochronological data performed on Variscan eclogites from the Argentera–Mercantour Massif, southwestern Alps. Based on the high-resolution field mapping, we present new eclogite occurrences and discuss the relationships between eclogites and surrounding migmatites. We recognized for the first time preserved eclogite facies assemblages. Trace elements and REE patterns establish that eclogites protoliths are MORBs contaminated by continental crust. Standard thermobarometry and thermodynamic modeling are consistent with P–T values of 640–740 °C for 1.5 ± 0.25 GPa, coherent with paleo-geotherms predicted for warm subduction of oceanic crust. We interpret these eclogites as a dismembered cryptic suture zone. 40Ar/39Ar dating on amphiboles yields an age of 339.7 ± 12 Ma for eclogite retrogression under amphibolite facies conditions. All these data are combined to link the Argentera–Mercantour Massif in the tectonic framework of both pre-Mesozoic Alpine basement and European southern Variscides.

Systematic Detection of Clustered Seismicity Beneath the Southwestern Alps

AbstractWe present a new automated earthquake detection and location method based on beamforming (or back projection) and template matching and apply it to study the seismicity of the Southwestern Alps. We use beamforming with prior knowledge of the 3‐D variations of seismic velocities as a first detection run to search for earthquakes that are used as templates in a subsequent matched‐filter search. Template matching allows us to detect low signal‐to‐noise ratio events and thus to obtain a high spatiotemporal resolution of the seismicity in the Southwestern Alps. We describe how we address the problem of false positives in energy‐based earthquake detection with supervised machine learning and how to best leverage template matching to iteratively refine the templates and the detection. We detected 18,754 earthquakes over 1 year (our catalog is available online) and observed temporal clustering of the earthquake occurrence in several regions. This statistical study of the collective behavior of earthquakes provides insights into the mechanisms of earthquake occurrence. Based on our observations, we infer the mechanisms responsible for the seismic activity in three regions of interest: the Ubaye valley, the Briançonnais, and the Dora Maira massif. Our conclusions point to the importance of fault interactions to explain the earthquake occurrence in the Briançonnais and the Dora Maira massif, whereas fluids seem to be the major driving mechanism in the Ubaye valley.

High resolution ambient noise tomography of the Southwestern Alps and the Ligurian margin

SUMMARY The Southwestern Alps and the Ligurian margin is a region of moderate seismicity with a high rate of small to moderate events. Identifying the active faults in this very densely populated region is critical to better assess the hazard and mitigate the risk. An accurate 3-D velocity model of the shallow to middle crust is a fundamental step to better locate the seismicity, and hence, the faults from which it originates. We performed ambient noise surface-wave tomography based on all available continuous seismological data from the French and Italian permanent networks (RESIF, INGV, RSNI), and current and past temporary experiments (AlpArray, CASSAT, SISVAR, RISVAL). In addition to these available data, we deployed three more stations to improve the spatial resolution in a region with sparse seismic station coverage. Overall, we used 55 inland seismic stations, 5 oceans bottom seismometers and 2 offshore cabled site/sensors. Data span the 2014–2018 time period. Time series from all available components were cross-correlated to reconstruct both Rayleigh and Love-wave Green's functions. For each station-pair Rayleigh and Love group velocity dispersion curves were semi-automatically picked using a frequency–time analysis. Then we regionalize these group velocities to build 2-D Rayleigh and Love velocity-maps between 1.5 and 9 s period. Using a two-step inversion, we estimate the best 3-D shear wave velocity model. The first step is based on a Neighbourhood Algorithm to recover the best three layers’ velocity model at each cell of the model. We then use this three-layer model as a starting model in a perturbational method based on finite elements. At periods up to 5 s, the spatial variation of the velocity is well correlated with the effective geology of the area. Lower velocities are observed in areas where the sedimentary cover is thicker, such as the Var and Paillon valley near Nice, or in the subalpine domain in the northwestern part of the region. Higher velocities are retrieved in areas where massifs are present, such as the Argentera-Mercantour massifs in the northeastern, or the Esterel massif in the southwestern part of the region.

Geographic isolation and climatic variability contribute to genetic differentiation in fragmented populations of the long-lived subalpine conifer Pinus cembra L. in the western Alps

BackgroundGenetic processes shape the modern-day distribution of genetic variation within and between populations and can provide important insights into the underlying mechanisms of evolution. The resulting genetic variation is often unequally partitioned within species’ distribution range and especially large differences can manifest at the range limit, where population fragmentation and isolation play a crucial role in species survival. Despite several molecular studies investigating the genetic diversity and differentiation of European Alpine mountain forests, the climatic and demographic constrains which influence the genetic processes are often unknown. Here, we apply non-coding microsatellite markers to evaluate the sporadic peripheral and continuous populations of cembra pine (Pinus cembra L.), a long-lived conifer species that inhabits the subalpine treeline ecotone in the western Alps to investigate how the genetic processes contribute to the modern-day spatial distribution. Moreover, we corroborate our findings with paleoecological records, micro and macro-remains, to infer the species’ possible glacial refugia and expansion scenarios.ResultsFour genetically distinct groups were identified, with Bayesian and FST based approaches, across the range of the species, situated in the northern, inner and south-western Alps. We found that genetic differentiation is substantially higher in marginal populations than at the center of the range, and marginal stands are characterized by geographic and genetic isolation due to spatial segregation and restricted gene flow. Moreover, multiple matrix regression approaches revealed effects of climatic heterogeneity in species’ spatial genetic pattern. Also, population stability tests indicated that all populations had experienced a severe historical bottleneck, no heterozygosity excess was detected, suggesting that more recently population sizes have remained relatively stable.ConclusionsOur study demonstrated that cembra pine might have survived in multiple glacial refugia and subsequently recolonized the Alps by different routes. Modern-day marginal populations, at the edge of the species’ range, could maintain stable sizes over long periods without inbreeding depression and preserve high amounts of genetic variation. Moreover, our analyses indicate that climatic variability has played a major role in shaping differentiation, in addition to past historical events such as migration and demographic changes.

Heaven and hell: Spotlights on some DNA barcodes for species identification and delimitation in ground beetles

In the face of the decline of many insects, there is an increasing demand for contemporary, fast and cost-effective approaches to monitor the development of populations and species. Numerous scientists favor molecular methods, especially those involving barcoding of the CO1 gene, as an alternative to classical, morphology-based species identification. Moreover, DNA barcoding is also discussed as a suitable method to support species delimitations in complexes of closely related taxa. We used the available sequences of ground beetles from North and Central Europe with additional ones we generated from Southern Europe and the Middle East to draw conclusion about the practicability of such approach for ground beetles. In general, while strong intraspecific differentiations within the CO1 fragment seem to characterize some wingless species (e.g. Graphipterus serrator, Siagona longula, Carabus problematicus, some Platycarabus species), others do not display much intraspecific variability (e.g. Graphipterus multiguttatus and G. sharonae within the “G. serrator clade”). These results certainly complicate the application of a metabarcoding approach without a larger database to delimitate these ground beetles. Furthermore, these results limit the applicability of the well-known barcoding gap, in ecological studies. With regards to taxonomic problems, mitochondrial and nuclear DNA sequences can provide support for taxonomic decisions. For example, the two taxa Carabus variolosus and nodulosus are characterized predominantely by K2P values lower than the barcoding gap. In view of the otherwise strong intraspecific differentiation within the genus Carabus, these two taxa should be regarded as subspecies. In contrast, DNA barcoding can also help to identify "good" species. Mitochondrial and nuclear data suggest, for example, that an Oreonebria taxon and a Platycarabus taxon from the South-western Alps represent "good species", although they were usually considered as synonyms or subspecies. In another case, two tiger beetle taxa, which until a few months ago were considered to belong to the same species, show such strong differentiation that only two species can be postulated (Calomera aulicoides and C. littoralis winkleri). In summary, we can state that DNA sequences and the barcoding gap can help to define species delimitations in ground beetles. However, several species, including widespread sister species, cannot be identified by DNA barcoding for various reasons (e.g. young species or horizontal gene flow). Consequently, until an automated, fast, and reliable method to identify species from samples emerges, ecological investigations have to rely on classical, morphology-based identifications.

Applying a hierarchisation method to a biodiversity hotspot: Challenges and perspectives in the South-Western Alps flora

The South-Western Alps host a great diversity of vascular plants, and especially endemic taxa. Thus, setting up a hierarchisation of patrimonial taxa of this biogeographical territory is needed in order to determine the main conservation concerns of flora. We adapted a hierarchisation method which leans on two criteria representing different kinds of rarity, and a third criterion which incorporates potential threats. This hierarchisation goes further than the objectives assigned to red lists and protection lists because it assesses taxa by taking into account the territorial context, using a standardised method, objective and reproducible. The classification of 913 patrimonial taxa into four concern categories aims to improve the available financial and human resources allocation for conservation measures.