Steep Crests Research Articles

Adsorption of Metformin on Graphene Nanoribbons and Application in Treatment of Oral Cancer Using Photothermal Energy

AbstractGraphene nanoribbons are thin sheets of graphene showing exclusive characteristics such as better drug‐loading capacity, adsorption on mammalian cells, greater surface area, and light‐absorbing ability. The current research work is to develop metformin‐adsorbed carboxyl‐functionalized oxidized graphene nanoribbons and utilize drug repurposing for the treatment of oral cancer by activating photo‐thermal radiation therapy. The nanoribbons are formulated by Hummer's method and evaluated for several characterization parameters like ATR‐ Fourier Transform Infrared (FTIR), Differential scanning calorimetry (DSC), topology, in vitro efficacy, ex vivo and in vitro cell line studies. The ATR‐FTIR spectrum of formulated nanoribbons shows distinctive peak at 3370 cm−1 (NH group) of metformin. The DSC specifies the incidence of steep endothermic crests at 235 °C (CNH3). The in vitro and ex vivo drug release studies show enhanced drug release in acidic pH (6.4) than physiological pH (7.4) with photothermal radiation. The in vitro cell line studies are processed via two‐way ANOVA that exhibits 67.74 ± 0.03% of % inhibition in presence of photothermal radiation. The study demonstrates higher inhibition of cancerous cells at lower concentration of drug and photothermal therapy in comparison to plain drug. The characteristic feature of graphene is used to develop targeted drug delivery system against the oral cancerous cells.

Effect of substrate morphology on the deposition behavior of α-Al2O3 films by room temperature granule spray in vacuum process

In this study, we investigated the influence of surface morphology of a hard substrate on the deposition behavior of α-Al2O3 films coated by a granule spray in vacuum (GSV) process at room temperature. Three types of α-Al2O3 films were prepared by chemical vapor deposition (CVD) on a WC-Co base material: (006) textured film with a uniform and small mold-type morphology, (110) and (012) textured films with large grains and a relatively flat morphology, and flat (006) textured film after polishing. These CVD α-Al2O3 films were further coated with nano-grained α-Al2O3 films by the GSV process. The deposition behavior, adhesion strength, and residual surface stress were found to be strongly influenced by the surface morphology of the hard substrate. For the (006) textured CVD α-Al2O3 film with steep crests and troughs on the surface, the GSV α-Al2O3 film was deposited uniformly, possibly because the powder can be directly anchored by the molding effect and subsequent hammering effect. Such different deposition characteristics also led to a variation in the surface residual stress.

Raindrop-Aware GAN: Unsupervised Learning for Raindrop-Contaminated Coastal Video Enhancement

We propose an unsupervised network with adversarial learning, the Raindrop-aware GAN, which enhances the quality of coastal video images contaminated by raindrops. Raindrop removal from coastal videos faces two main difficulties: converting the degraded image into a clean one by visually removing the raindrops, and restoring the background coastal wave information in the raindrop regions. The components of the proposed network—a generator and a discriminator for adversarial learning—are trained on unpaired images degraded by raindrops and clean images free from raindrops. By creating raindrop masks and background-restored images, the generator restores the background information in the raindrop regions alone, preserving the input as much as possible. The proposed network was trained and tested on an open-access dataset and directly collected dataset from the coastal area. It was then evaluated by three metrics: the peak signal-to-noise ratio, structural similarity, and a naturalness-quality evaluator. The indices of metrics are 8.2% (+2.012), 0.2% (+0.002), and 1.6% (−0.196) better than the state-of-the-art method, respectively. In the visual assessment of the enhanced video image quality, our method better restored the image patterns of steep wave crests and breaking than the other methods. In both quantitative and qualitative experiments, the proposed method more effectively removed the raindrops in coastal video and recovered the damaged background wave information than state-of-the-art methods.

Lagrangian Measurement of Steep Directionally Spread Ocean Waves: Second-Order Motion of a Wave-Following Measurement Buoy

AbstractThe notion that wave-following buoys provide less accurate measurements of extreme waves than their Eulerian counterparts is a perception commonly held by oceanographers and engineers (Forristall 2000,J. Phys. Oceanogr.,30, 1931–1943,https://doi.org/10.1175/1520-0485(2000)030<1931:WCDOAS>2.0.CO;2). By performing a direct comparison between the two types of measurement under laboratory conditions, we examine one of the hypotheses underlying this perception and establish whether wave measurement buoys in extreme ocean waves correctly follow steep crests and behave in a purely Lagrangian manner. We present a direct comparison between Eulerian gauge and Lagrangian buoy measurements of steep directionally spread and crossing wave groups on deep water. Our experimental measurements are compared with exact (Herbers and Janssen 2016,J. Phys. Oceanogr.,46, 1009–1021,https://doi.org/10.1175/JPO-D-15-0129.1) and new approximate expressions for Lagrangian second-order theory derived herein. We derive simple closed-form expressions for the second-order contribution to crest height representative of extreme ocean waves—namely, for a single narrowly spread wave group, two narrowly spread crossing wave groups, and a single strongly spread wave group. In the limit of large spreading or head-on crossing, Eulerian and Lagrangian measurements become equivalent. For the range of conditions that we test, we find that our buoy behaves in a Lagrangian manner, and our experimental observations compare extremely well to predictions made using second-order theory. In general, Eulerian and Lagrangian measurements of crest height are not significantly different for all degrees of directional spreading and crossing. However, second-order bound-wave energy is redistributed from superharmonics in Eulerian measurements to subharmonics in Lagrangian measurement, which affects the “apparent” steepness inferred from time histories and poses a potential issue for wave buoys that measure acceleration.

Numerical modelling of nonlinear extreme waves in presence of wind

A numerical wave flume with fully nonlinear free surface boundary conditions is adopted to investigate the temporal characteristics of extreme waves in the presence of wind at various speeds. Incident wave trains are numerically generated by a piston-type wave maker, and the wind-excited pressure is introduced into dynamic boundary conditions using a pressure distribution over steep crests, as defined by Jeffreys’ sheltering mechanism. A boundary value problem is solved by a higher-order boundary element method (HOBEM) and a mixed Eulerian-Lagrangian time marching scheme. The proposed model is validated through comparison with published experimental data from a focused wave group. The influence of wind on extreme wave properties, including maximum extreme wave crest, focal position shift, and spectrum evolution, is also studied. To consider the effects of the wind-driven currents on a wave evolution, the simulations assume a uniform current over varying water depth. The results show that wind causes weak increases in the extreme wave crest, and makes the nonlinear energy transfer non-reversible in the focusing and defocusing processes. The numerical results also provide a comparison to demonstrate the shifts at focal points, considering the combined effects of the winds and the wind-driven currents.

Hydrogeology and Hydromorphology: a Proposal for a Dual-Key Approach to Assess the Geo-Hydrological Heritage Site of the San Lucano Valley (Belluno Dolomites, Italy)

Hydrological features are a fundamental element of the whole “geoheritage” of a site. It is, indeed, possible to identify the “water heritage” part related to the value of water and its phenomena. Recent studies were carried out in the San Lucano Valley (Belluno, Italy) and its geological, geomorphological and hydrological observations can help to perceive some natural occurrences as “hydrological heritage”. They are a solid background that helps us to analyse and bring into evidence the exceptionality of the hydrogeological features of this site. San Lucano Valley thanks to its numerous springs and to its particular morphology characterized by steep slopes and crest rising up above the valley floor, represents a unique “window” in the core of a karst carbonatic aquifer. This peculiar topographical setting enables a 3D view of the groundwater flow, from the recharge areas to the spring and alpine stream from its headwaters to where it becomes a tributary of a bigger river. To classify the springs of the valley and to underline their peculiar hydrogeological features, several surveys were performed, discharge in streams and springs was regularly measured using current meters, and the water level was monitored on site in reference cross sections (this activity is still in progress). In order to assess the stream hydromorphology, the geomorphic method of Rosgen (Catena 22:166–199, 1994) (RSC) has been adopted collecting a series of detailed survey datasets along the entire watercourse. Following the path indicated by Simic et al. (Carpathian J Earth Environ Sci 9(4):19–30, 2014), adapted to the specific case, the whole hydrological and hydromorphological system has been assessed. For all the above reasons, San Lucano Valley could be proposed as a Hydrological Heritage Site “valuable” for geo-tourism in the Dolomite’s UNESCO Area 3.

Detailed measurements of interfacial dynamics in air-water pipe flow

Stratified air-water flow in a horizontal pipe is investigated experimentally using particle image velocimetry and conductance probes. This flow regime is characterized by a complex interplay between a turbulent airflow and propagating waves at the interface. The waves are generated by interfacial shear and pressure forces exerted by the faster flowing airflow. The goal of this study is to characterize the waves by means of statistical and spectral methods, and to explore the influence of different wave regimes on the airflow.Two cases in which the air bulk velocity increases from 2.4 m/s (case A) to 3.5 m/s (case B), while the liquid velocity remains constant at 0.26 m/s, are assessed in detail. Case A belongs to a region of flow conditions in which wave amplitudes grow as a consequence of increasing gas flow rates, i.e., wave growth regime. Meanwhile, case B is in a regime of saturated wave amplitudes. In the first case, the interface was populated by small amplitude 2D waves of relatively small steepness (ak ≈ 0.07). These waves obey Gaussian statistics and are thus considered to be linear. In the second case, the waves are larger, steeper (ak ≈ 0.13) and considerably more irregular. They display non-linear behaviour (steep crests and long troughs) and their exceedance probability distribution deviates significantly from Gaussian statistics. Bicoherence maps show evidence of both overtone and sub-harmonic interactions.Airflow velocity fields acquired by PIV were subjected to a conditional phase-averaging method based on a steepness criterion. The phase-averaged vorticity field shows evidence of shear-layer separation above the steeper waves of case B. Hence, in addition to non-linear mode interactions and micro-breaking, shear-layer separation may contribute to the transition from the growth regime to the saturation regime.

Wind and Current Effects on Extreme Wave Formation and Breaking

AbstractWind and current effects on the evolution of a two-dimensional dispersive focusing wave group are investigated using a two-phase flow model. A Navier–Stokes solver is combined with the Smagorinsky subgrid-scale stress model and volume of fluid (VOF) air–water interface capturing scheme. Model predictions compare well with the experimental data with and without wind. It was found that the following and opposing winds shift the focus point downstream and upstream, respectively. The shift of focus point is mainly due to the action of wind-driven current instead of direct wind forcing. Under strong following/opposing wind forcing, there appears a slight increase/decrease of the extreme wave height at the focus point and an asymmetric/symmetric behavior in the wave focusing and defocusing processes. Under a weak following wind, however, the extreme wave height decreases with increasing wind speed because of the dominant effect of the wind-driven current over direct wind forcing. The vertical shear of the wind-driven current plays an important role in determining the location of and the extreme wave height at the focus point under wind actions. Furthermore, it was found that the thin surface layer current is a better representation of the wind-driven current for its role in wind influences on waves than the depth-uniform current used by previous studies. Airflow structure above a breaking wave group and its link to the energy flux from wind to wave as well as wind influence on breaking are also examined. The flow structure in the presence of a following wind is similar to that over a backward-facing step, while that in the presence of an opposing wind is similar to that over an airfoil at high angles of attack. Both primary and secondary vortices are observed over the breaking wave with and without wind of either direction. Airflow separates over the steep crest and causes a pressure drop in the lee of the crest. The resulting form drag may directly affect the extreme wave height. The wave breaking location and intensity are modified by the following and opposing wind in a different fashion.

Lagrangian Kinematic Criterion for the Breaking of Shoaling Waves

AbstractAn experimental study was conducted with the aim of validating the Lagrangian kinematic criterion (LKC) for the case of breaking of shoaling waves. Monochromatic wave trains were generated in a large wave flume and allowed to shoal and break naturally on an artificial inclination changeable shore, thus allowing inspection of a range of slopes. Instantaneous horizontal Lagrangian water surface velocity was measured by particle tracking velocimetry and compared to the instantaneous propagation speed of the crest on a verge of breaking, the latter calculated using time series produced by resistance-type wave gauges staged along the flume. The inception of a breaker was found to occur when the monotonically increasing horizontal water velocity on the crest, during the process of steepening, approached that of the slowing steep crest, thus confirming the LKC for shoaling conditions. In addition, an objective method of breaking detection was developed utilizing the phase–time method and wavelet analysis by recognizing a specific pattern in the instantaneous local frequency fluctuations. The two main expected contributions of this study are the formation of an applicable criterion for breaking occurrences in shoaling waves and development of a wave breaking detection method independent of human decision. Incorporation of the suggested criterion into existing waves prediction models can be a significant contribution to maritime projects efficiency, whereas the breakers detection method will be useful for conducting further experimental research on waves breaking both in laboratory installations and in the highly unstable environment of an open sea.

First record of Evoxymetopon taeniatus (Actinopterygii: Perciformes: Trichiuridae) from the Philippines

The channel scabbardfish, Evoxymetopon taeniatus Gill, 1863 has not been known from the Philippine waters. Our presently reported finding of two specimens (114.5 and 133.1 cm SL)  of this species from the Philippines extends the range of this species to the central Indo-Pacific. The specimens captured were both male, one with developing gonads, and the other one—mature. We examined and described the fish found, providing morphometric and meristic analyses. The species can be distinguished from its congeners by having a convex upper head profile, steep sagittal crest slope, 82 dorsal fin rays with a defined notched at the tenth ray, a black dorsal fin membrane before the notch, and 15 externally visible anal fin rays that are bound with a membrane. The analyses included also relations with size of the four known Evoxymetopon species. Only one significant relation was revealed by the regression analyses—between SL and % pre-anal length. We provided also an updated identification key for the genus.

Experimental and Numerical Studies of Circular Footing Resting on Confined Granular Subgrade Adjacent to Slope

Many situations exist where foundations must be constructed on or near slopes. As a result, the foundation’s bearing capacity is reduced, and the slope might collapse. This paper presents the results of laboratory and numerical model tests on the influence of soil confinement on the behavior of a model footing adjacent to slopes. Confining cylinders with different heights, each set back some distance from the slope crest, were adopted. The ultimate bearing capacity of a circular footing supported on a confined sand bed adjacent to a slope was studied. The studied parameters include the cell-embedment depth, slope angle, and subgrade density. The results indicate that the bearing load capacities of circular footings at any edge distance from the slope crest can be appreciably increased by soil confinement. The slope effect on the ultimate bearing capacity can be neglected when the cell-footing system is placed at setback distance with cell-embedment depth around two times the cell diameter. When the cell-footing system is placed directly on a steep slope crest, the improvement in the bearing capacity reached 4, 2.2, and 1.9 times the footing with subgrade relative densities of 80, 55, and 35%, respectively. The numerical analysis helped to explain the deformation behavior of cell-footing soil systems adjacent to a slope. It provides a realistic failure mechanism of the new system and illustrates how the cell can protect the slope from collapse by decreasing slope deformation.

An experimental investigation on the effects of surface gravity waves on the water evaporation rate in different air flow regimes

Estimating rate of evaporation from undisturbed water surfaces to moving and quiet air has been the topic a vast number of research activities. The obvious presence of various shapes of gravity waves on the water body surfaces was the motivation of this experimental investigation. In this investigation experimental measurements have been done to quantify evaporation rate from wavy water surfaces in free, mixed and forced convection regimes. The effects of a wide range of surface gravity waves from low steepness, round shaped crest with slow celerity, to steep and very slight spilling crest waves, on the water evaporation rate have been investigated. A wide range of \({\text{Gr}}/{\text{Re}}^{2} (0.01 \le {\text{Gr}}/{\text{Re}}^{2} \le 100)\) was achieved by applying different air flow velocities on a large heated wave flume equipped with a wind tunnel. Results reveal that wave motion on the water surface increase the rate of evaporation for all air flow regimes. For free convection, due to the effect of wave motion for pumping rotational airflows at the wave troughs and the dominant effect of natural convection for the air flow advection, the maximum evaporation increment percentage from wavy water surface is about 70 %. For mixed and forced convection, water evaporation rate increment is more sensitive to the air flow velocity for the appearance of very slight spilling on the steep wave crests and the leeward air flow structures.

Distribution and inferred age of exfoliation joints in the Aar Granite of the central Swiss Alps and relationship to Quaternary landscape evolution

Exfoliation joints are well-known natural fractures limited to near the ground surface. Relatively few details, however, are known about their distribution and age in the Swiss Alps. Exfoliation joints follow the landscape surface at the time of their formation; the age of the associated landscape feature then provides a maximum age of exfoliation joints. While landscape forms can change through time, exfoliation joints preserve elements of former landscape morphologies by their undisturbed orientations. The Grimsel region of the Central Alps is well-suited for analyzing the impact of erosional episodes, and accompanying stress changes, on exfoliation joint formation in granitic rocks. Mapping above and below ground revealed that exfoliation joints are widespread and occur between valley bottoms and mountain crests within glacial (inner and hanging U-shaped trough valleys, glacial cirques, and steep mountain crests) and predominantly fluvial landforms (gently inclined linear slopes above the inner trough valleys, narrow inner-valley gorges, and steep V-shaped side gullies). Based primarily on their geometric properties at the ground surface, three exfoliation joint types were distinguished in our study area: (1) closely spaced (<1m) joints oriented distinctly parallel to the present-day ground surface, (2) intermediately spaced (0.6–2m) joints that are nearly parallel (<10° difference) to today's mean ground surface at a 10-m scale, and (3) widely spaced (≫2m) joints not parallel to the ground surface. Relating the mapped distribution of exfoliation joint types to identified erosional episodes and landscape features of known and inferred ages, respectively, enables us to distinguish four exfoliation joint generations in the Grimsel area, which most likely formed during the lower Pleistocene (~1.5–1Ma), middle Pleistocene (~0.7–0.4Ma), upper Pleistocene (0.1–0.02Ma), and Late Glacial/Holocene (<0.02Ma). We demonstrate that the most prominent and deepest exfoliation joint generation is associated with erosion of the inner glacial troughs of the upper Aar valley, which likely occurred during the mid-Pleistocene Revolution. Our study shows how exfoliation joint episodes can be dated, and, conversely, that better knowledge of the distribution of exfoliation joint sets can reveal unique information about the morphological evolution of an Alpine valley.

Double-Ridge Internal Tide Interference and Its Effect on Dissipation in Luzon Strait

Abstract Luzon Strait between Taiwan and the Philippines features two parallel north–south-oriented ridges. The barotropic tides that propagate over these ridges cause strong internal waves and dissipation. The energy dissipation mechanisms and the role of the baroclinic wave fields in this dissipation are investigated using numerical simulations with the Massachusetts Institute of Technology general circulation model (MITgcm). The model is integrated over two-dimensional configurations along a zonal transect at 20.6°N for a maximum duration of a spring–neap cycle. Nearly all dissipation occurs at the steep ridge crests due to high-mode turbulent lee waves with horizontal scales of several kilometers and vertical scales of hundreds of meters. The spatial structure and timing of the predicted velocities and dissipation agree with observations and confirm the existence of these lee waves. The lee wave strength is greatly affected by the internal waves generated at the other ridge. When semidiurnal barotropic tides are dominant, the internal wave beams from both ridges nearly superpose after one surface reflection. The remotely generated internal waves from both ridges are therefore in phase with each other and the barotropic tides at the ridges. The barotropic-to-baroclinic energy conversion, energy flux divergence, ridge top velocities, and dissipation are stronger compared to the sum of the single east ridge and single west ridge cases. When diurnal tides are dominant, the wave fields are more out of phase and the conversion, divergence, and dissipation are less than or equal to the single ridge cases combined.

Characterization of Pyroclastic Deposits and Pre-eruptive Soils following the 2008 Eruption of Kasatochi Island Volcano, Alaska

The 7–8 August 2008 eruption of Kasatochi Island volcano blanketed the island in newly generated pyroclastic deposits and deposited ash into the ocean and onto nearby islands. Concentrations of water soluble Fe, Cu, and Zn determined from a 1:20 deionized water leachate of the ash were sufficient to provide short-term fertilization of the surface ocean. The 2008 pyroclastic deposits were thicker in concavities at bases of steeper slopes and thinner on steep slopes and ridge crests. By summer 2009, secondary erosion had exposed the pre-eruption soils along gulley walls and in gully bottoms on the southern and eastern slopes, respectively. Topographic and microtopographic position altered the depositional patterns of the pyroclastic flows and resulted in pre-eruption soils being buried by as little as 1 m of ash. The different erosion patterns gave rise to three surfaces on which future ecosystems will likely develop: largely pre-eruptive soils; fresh pyroclastic deposits influenced by shallowly buried, pre-eruptive soil; and thick (>1 m) pyroclastic deposits. As expected, the chemical composition differed between the pyroclastic deposits and the pre-eruptive soils. Pre-eruptive soils hold stocks of C and N important for establishing biota that are lacking in the fresh pyroclastic deposits. The pyroclastic deposits are a source for P and K but have negligible nutrient holding capacity, making these elements vulnerable to leaching loss. Consequently, the pre-eruption soils may also represent an important long-term P and K source.

Hydrodynamic Processes and Bedload Transport Associated with Large-Scale Sandwaves in the Taiwan Strait

Hydrodynamic processes and bedload transport over a large-scale sandwave field were analyzed along three transects in Taiwan Strait based on measurements of water depth, current velocities within the water column, and the physical properties of the sediment at the seabed. The sandwaves in consideration have steep crests and flat troughs, with a width of 14.4–20.3 m and a length of 325–820 m. Generally, the mean H/L ratio falls in the range of large-scale sandwaves, but the ratio is larger than the average, deviating from the global trend. The H/d ratio is much higher than the global average. The current-velocity vectors at the sandwave crests, troughs, stoss sides, and lee sides turned in a clockwise manner within a tidal cycle; the current speed above the crest was relatively larger than above the trough. During the flood tide, the current speed reached a maximum in the layer 9–11 m below the water surface. During the measurement period, there was net accumulation of sediment over the study area. The migration of the sandwaves caused by bedload transport varied widely at different transects: for the three transects in consideration, migration in the flood direction occurred at two transects, with different migrating speeds; and ebb-dominated migration occurred at the third transect. The migration rate predicted by the bedload transport calculations, based on tidal current measurements, is lower than long-term observations by remote sensing, which may be due to the fact that this region is frequently influenced by storm events, and the long-term migration patterns are related to the enhanced currents and waves during storms. Further, time-velocity asymmetry of the tidal currents, as observed in the present study, may also favor the enhanced migration rate during storm events.

Focusing wave group in shallow water in the presence of wind

The influence of wind on extreme wave events in shallow water is investigated numerically. A series of numerical simulations using a pressure distribution over the steep crests given by the modified Jeffreys' sheltering theory shows that wind blowing over a strongly modulated wave group due to the dispersive focusing of a chirped long wave packet increases the time duration and maximal amplitude of the extreme wave event. These results are coherent with those obtained within the framework of deep water. However, steep wave events are less unstable to wind perturbation in shallow water than in deep water.

Dynamics of Winds and Currents Coupled to Surface Waves

We discuss the coupling processes between surface gravity waves and adjacent winds and currents in turbulent boundary layers. These processes mediate exchanges of momentum, heat, and gases between the atmosphere and ocean and thus are of global significance for climate. Surface waves grow primarily by pressure-form stress from airflow over the waveforms, and they dissipate in the open sea by wave breaking that injects and stirs momentum, energy, and bubbles into the ocean. Wave motions pump wind eddies that control fluxes across the lower atmosphere. Flow separation occurs behind steep wave crests, and at high winds the crests flatten into spume, which diminishes the drag coefficient. In the ocean the Lagrangian-mean wave velocity, Stokes drift, induces a vortex force and material transport. These generate Langmuir circulations penetrating throughout the boundary layer and enhancing entrainment at the stratified interior interface in combination with other turbulent eddies and inertial-shear instability.

Higher-harmonic focused-wave forces on a vertical cylinder

This paper considers higher-harmonic forces due to wave focusing on a vertical circular cylinder. A series of experiments has been conducted in a wave flume. The first six-harmonic components of the measured wave forces are analyzed using the scale-averaged wavelet spectrum. It is noted that due to the transient nature of focused (freak) waves, Fourier analysis would not provide equivalent information to that gleaned from the analyses used herein. The results for the experiments with very steep wave crests show significant amplitudes at the fourth and fifth harmonics. These harmonics exhibit amplitudes that are the same order as the second harmonic, but much larger than those of the third harmonic. The wavelet-based bicoherence is used to detect the quadratic nonlinearity of the measured forces. And the bicoherence spectra reveal the primary mathematical reason for the existence of the striking amplitudes of the fourth and fifth harmonics: the interaction between the lower-harmonic components couple more strongly with the fourth and fifth harmonics, thus the fourth and fifth harmonics glean more energy than those of the third-harmonic components. However, the physical explanation for this remains elusive.

Ecological magnitude and fine scale dynamics of the mediterranean narrow endemic therophyte, Arenaria provincialis (Caryophyllaceae)

In the context of plant species rarity in mediterranean ecosystems, this study aims to precise the autoecology of the local annual endemic plant, Arenaria provincialis (Caryophyllaceae), by quantifying habitat and vegetation characteristics, and demographic parameters. Its populations are surprisingly scattered along a wide altitudinal and topological range, but over small geographical distances. This implies an important habitat differentiation from the thermophilous dry coast to the colder supra—mediterranean summits in open limestone rocky habitats such as steep screes, ledges, cracks or crests. Among the 163 plant species identified in presence of A. provincialis within 100 m2 area, 92% belong to the stress Grime pole, highlighting the stressful conditions within the different habitats caused by drought, strong wind, and high thermic contrasts. Demographical surveys reveal strong spatial and temporal fluctuations.