Calcareous Substrates Research Articles

Small-scale drivers on plant and ant diversity in a grassland habitat through a multifaceted approach

Semi-natural grasslands are characterized by high biodiversity and require multifaceted approaches to monitor their biodiversity. Moreover, grasslands comprise a multitude of microhabitats, making the scale of investigation of fundamental importance. Despite their wide distribution, grasslands are highly threatened and are considered of high conservation priority by Directive no. 92/43/EEC. Here, we investigate the effects of small-scale ecological differences between two ecosites present within the EU habitat of Community Interest of semi-natural dry grasslands on calcareous substrates (6210 according to Dir. 92/43/EEC) occurring on a Mediterranean mountain. We measured taxonomic and functional diversity of plant and ant communities, evaluating the differences among the two ecosites, how these differences are influenced by the environment and whether vegetation affects composition of the ant community. Our results show that taxonomic and functional diversity of plant and ant communities are influenced by the environment. While vegetation has no effect on ant communities, we found plant and ant community composition differed across the two ecosites, filtering ant and plant species according to their functional traits, even at a small spatial scale. Our findings imply that small-scale monitoring is needed to effectively conserve priority habitats, especially for those that comprise multiple microhabitats.

News from the western front: occurrence of Mediterranea depressa (Sterki, 1880) (Mollusca: Gastropoda: Oxychilidae) in the Vosges and Jura Mountains (north-eastern France)

We report here the first record of Mediterranea depressa (Sterki, 1880) in the north-eastern quarter of France, in the Vosges and Jura massifs. After the fortuitous discovery of some shells attributed to M. depressa in the southern Vosges Mts., an extensive sampling campaign was carried out both in the Vosges and in the Jura Mts. In total, about 20 shells and seven live specimens were found at eight localities, which, according to the present state of our knowledge, represent its north-western range limit. The species was found exclusively under stones of rocky slope screes on siliceous and calcareous substrates. Some of these habitats could be described as Mesovoid Shallow Substratum. It is not clear whether the rarity of the species is an effect of under-sampling or of its small size and unusual habitat or/and to intrinsic rarity due to isolated populations at the distribution limits of the species. The extreme north-eastern quarter of France constitutes an oceanic-continental transition zone where about thirty gastropod species from Central and Eastern Europe are currently documented at the western limit of their ranges.

Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia

Oyster shells are substratum for different epibiontic and endobiontic organisms, including pests and parasites. Rocellaria dubia is endolithic and facultative tube-dwelling bivalve, boring in different calcareous substrates, including the shells of bivalves. In 2020, R. dubia was found as endolithic in the shells of the Pacific oyster Magalana gigas, from an oyster farm off the Sacca di Goro lagoon (Emilia-Romagna region, Northern Adriatic Sea, Italy). The purpose of this study was to describe this newly recorded association. Altogether, 136 specimens of R. dubia were found in 15 oysters, photographed under a stereoscope, and their length was measured. Heavily infested oysters hosted tens of R. dubia borers, which were perforating the whole thickness of the oyster valves. The flesh of these oysters was heavily damaged, suggesting parasitic association. R. dubia specimens were categorized into three age classes (0–1, 1–2, and 2–3 years old). M. gigas/R. dubia might be a widespread association, overlooked due to the very scarce research on macrofauna associated with M. gigas. Considering the negative effects of R. dubia endobiosis on oyster fitness, and possible impacts on oyster aquaculture, further research should be conducted in order to elucidate the distribution and ecological characteristics of this parasitic association.

A synthetic phytosiderophore analog, proline-2\u2032-deoxymugineic acid, is efficiently utilized by dicots

PurposePhytosiderophores (PS) from grasses solubilize sparingly soluble iron (Fe), and the resultant PS-Fe is an Fe source even for dicots. Recently, the synthetic PS proline-2′-deoxymugineic acid (PDMA) has been developed as a moderately biodegradable Fe fertilizer for grasses. We aimed to investigate whether PDMA-Fe is also a good Fe source for dicots.MethodsThe availability of PDMA-Fe to cucumber was evaluated in a calcareous substrate and hydroponic cultures at pH 7.0–9.0 by determining chlorophyll level, PSII activity, and Fe uptake. EDDHA-Fe, EDTA-Fe, and citrate-Fe were used as controls. The reducibility of Fe chelates by roots was measured to determine the mechanism underlying differences in availability. Expressions of Fe deficiency-inducible genes were analyzed to estimate the Fe status in plants.ResultsThe application of PDMA-Fe and EDDHA-Fe to a calcareous substrate reduced Fe-deficient chlorosis to a similar extent; however, the shoot Fe concentration was higher in the PDMA-Fe treatment. In the hydroponic culture, the availability of PDMA-Fe was higher than that of the other chelates at all pH levels, and this was confirmed by higher PSII activity and lower expression of Fe deficiency-inducible genes. The reducibility assay revealed that the reduction level of PDMA-Fe was greater than that of EDTA-Fe and citrate-Fe under alkaline pH.ConclusionsPDMA-Fe is utilized by cucumber roots more efficiently than traditional synthetic chelates in both calcareous substrate and hydroponic cultures. The higher availability of PDMA-Fe may be attributed to its higher reducibility. Our findings suggest that PDMA-Fe could be a good Fe fertilizer for dicots.

The composition, geography, biology and assembly of the coastal flora of the Cape Floristic Region.

The Cape Floristic Region (CFR) is globally recognized as a hotspot of plant diversity and endemism. Much of this diversity stems from radiations associated with infertile acid sands derived from sandstones of the geologically ancient Cape Fold Belt. These ancient montane floras acted as the source for most subsequent radiations on the Cape lowlands during the Oligocene (on silcretes) and Mio–Pliocene (on shales). The geomorphic evolution of the CFR during the Plio–Pleistocene led to the first large-scale occurrence of calcareous substrata (coastal dunes and calcarenites) along the Cape coast, providing novel habitats for plant colonization and ensuing evolution of the Cape coastal flora—the most recent diversification event in the Cape. Few studies have investigated the CFR’s dune and calcarenite floras, and fewer still have done so in an evolutionary context. Here, we present a unified flora of these coastal calcareous habitats of the CFR and analyze the taxonomic, biological and geographical traits of its component species to gain insights into its assembly. The Cape coastal flora, comprising 1,365 species, is taxonomically dominated by the Asteraceae, Fabaceae and Iridaceae, with Erica, Aspalathus and Agathosma being the most speciose genera. In terms of growth-form mix, there is a roughly equal split between herbaceous and woody species, the former dominated by geophytes and forbs, the latter by dwarf and low shrubs. Species associated with the Fynbos biome constitute the bulk of the flora, while the Subtropical Thicket and Wetland biomes also house a substantial number of species. The Cape coastal flora is a distinctly southern African assemblage, with 61% of species belonging to southern African lineages (including 35% of species with Cape affinity) and 59% being endemic to the CFR. Unique among floras from the Cape and coastal Mediterranean-climate regions is the relatively high proportion of species associated with tropical lineages, several of which are restricted to calcareous substrata of the CFR. The endemic, calcicolous component of the flora, constituting 40% of species, represents 6% of the Cape’s regional plant diversity—high tallies compared to other biodiversity hotspots. Most coastal-flora endemics emerged during the Plio–Pleistocene as a product of ecological speciation upon the colonization of calcareous substrata, with the calcifugous fynbos floras of montane acid substrata being the most significant source of this diversification, especially on the typically shallow soils of calcarenite landscapes. On the other hand, renosterveld floras, associated with edaphically benign soils that are widespread on the CFR lowlands, have not been a major source of lineages to the coastal flora. Our findings suggest that, over and above the strong pH gradient that exists on calcareous substrata, soil depth and texture may act as important edaphic filters to incorporating lineages from floras on juxtaposed substrata in the CFR.

Notes on the distribution, ecology, associated vegetation and conservation status of Gymnadenia (Orchidaceae) in Kosovo

Four species of Gymnadenia are native to Kosovo: G. conopsea, G. frivaldii, G. nigra, and G. odoratissima. In this study, field expedition data, phytosociological relevés, herbarium specimens along with extensive literature sources were used to analyse vegetation and ecological characteristics, habitat types, distributional patterns as well as provide notes on conservation. Gymnadenia conopsea is distributed throughout the country, from lowlands to the alpine belt. It was recorded in various plant communities. Gymnadenia frivaldii grows in the alpine zone of mountains, close to streams and in wet meadows. Its relevés belong to the class Scheuchzerio-Caricetea fuscae. This species is classified as “Near Threatened” (NT) in Kosovo. Gymnadenia nigra grows in subalpine and alpine grassland on preferably calcareous substrate. It has been found in almost all mountains reaching >2000 m a.s.l., and occurs in different plant communities belonging to the class: Elyno-Seslerietea. Gymnadenia odoratissima was recorded from one locality only in Kosovo, on the massif of Maja e Zezë, Sharri Mts. It was growing in degraded beech forest and meadows on silicate bedrock. Its floristically diverse relevés associate with the class: Mulgedio-Aconitetea. Of the four studied species, G. frivaldii deserves more conservation attention because of its fragile populations.

Bioeroding sponge species from the Wakatobi region of southeast Sulawesi, Indonesia.

Sponges that excavate and inhabit calcareous substrate, predominantly of the Clionaidae, are widely distributed in marine habitats, but are particularly diverse and abundant on coral reefs. Unfortunately, their cryptic habit and difficult taxonomy mean respective taxa are poorly understood, and therefore they are rarely included in reef surveys. This is particularly true of the Southeast Asian Indo-Pacific, where a diverse faunistic record is contrasted with a very limited understanding of eco-physiological requirements of these sponges. In light of this, in situ surveys of the most common bioeroding sponges in the Wakatobi region of Southeast Sulawesi, Indonesia were conducted, followed by morphological and molecular analysis. The seven most common species in the Wakatobi included five species with a wide Indo-Pacific distribution and two new species. Four species, Cliona orientalis, Cliona aff. schmidtii, Spheciospongia cf. vagabunda trincomaliensis and Cliothosa hancocki have been previously reported from Indonesian waters, while Zyzzya criceta is a new record for Indonesia. Two brown sponges belonging to the Cliona viridis species complex, Cliona wakatobiensis sp. nov. and Cliona cribripora sp. nov., are here described as new to science. They were morphologically distinct from other species in the sample region and could not conclusively be allocated to any other known clionaid species. A maximum likelihood analysis of ITS1 rDNA revealed them to be phylogenetically closer to other Indo-Pacific species such as Cliona orientalis and Cliona thomasi than to other species within this taxon complex.

Description of Paraxiopsis/ kensleyi/ n. sp., a new axiid lobster from the Gulf of Mexico (Crustacea: Decapoda: Axiidea).

A new species of axiid was discovered during sampling offshore deep banks on the middle continental shelf off Louisiana. Paraxiopsis kensleyi n. sp. appears to inhabit interstices and cavities of coralline algal rubble, rhodoliths, coral rubble, and other eroded calcareous substrates. Weakly separated from Eutrichocheles Wood-Mason, 1876 on the basis of morphology, present assignments of western Atlantic species to Paraxiopsis de Man, 1905 are regarded as provisional. The new species is described morphologically, and the coloration of freshly captured specimens is documented and compared to related species where possible. Coloration readily distinguishes mature specimens of the new species from Paraxiopsis spinipleura Kensley, 1996, with which it was initially confused. The diagnosis includes GenBank accession numbers for COI sequences to allow future molecular phylogenetic comparisons. Compared to regional species that share a similar dentation or spination on the submedian carina, the pleon of the new species is distinctive in the truncate ventral margin on pleura 2-4, as opposed to being broadly rounded or directed ventrally in an acutely triangular tip. The new species is the eighteenth species of Paraxiopsis worldwide and the ninth from western Atlantic waters, seven of which are now known to range into the Gulf of Mexico. An updated key to western Atlantic members of the genus is provided.

A multi-proxy long-term ecological investigation into the development of a late Holocene calcareous spring-fed fen ecosystem (Raganu Mire) and boreal forest at the SE Baltic coast (Latvia)

The calcareous substrate of spring-fed fens makes them unique islands of biodiversity, hosting endangered, vulnerable, and protected vascular plants. Hence, spring-fed fens ecosystems require special conservation attention because many of them are destroyed (e.g. drained, forested) and it is extremely difficult or even impossible to restore the unique hydrogeological and geochemical conditions enabling their function. The long-term perspective of paleoecological studies allows indication of former wetland ecosystem states and provides understanding of their development over millennia. To examine the late Holocene dynamics of a calcareous spring-fed fen (Raganu Mire) ecosystem on the Baltic Sea coast (Latvia) in relation to environmental changes, substrate and human activity, we have undertaken high-resolution analyses of plant macrofossils, pollen, mollusc, stable carbon (δ13C) and oxygen (δ18O) isotopes combined with radiocarbon dating (AMS) in three coring locations. Our study revealed that peat deposits began accumulating ca. 7000 cal. yr BP and calcareous deposits (tufa) from 1450 cal. yr BP, coinciding with regional hydrological changes. Several fire events occurred between 4000 and 1600 cal. yr BP, which appeared to have had a limited effect on local vegetation. The most significant changes in the forest and peatland ecosystems were at 3200 cal. yr BP associated with a dry climate stage and high fire activity, and then between 1400 and 500 cal. yr BP potentially associated with temperature changes during the Medieval Climate Anomaly (MCA) and Little Ice Age. Hydrological disturbances in the peatland catchment from 1400 cal. yr BP were most likely strengthened by human activity (deforestation) in this region. The relationship between the development of this peatland and changes in its catchment area, such as land cover changes or fluctuations in groundwater levels, suggest that protection and restoration of spring-fed fen ecosystems should also include the surrounding catchment. The presence of calcareous sediments, as well as appropriate temperature and local hydrological conditions appear to be the most crucial factors controlling Cladium marisus populations in our site - currently at the eastern limit of its distribution in Europe.

Hydrogeochemical and Hydrodynamic Assessment of Tirnavos Basin, Central Greece

A combined hydrogeochemical and hydrodynamic characterization for the assessment of key aspects related to groundwater resources management was performed in a highly productive agricultural basin of the Thessaly region in central Greece. A complementary suite of tools and methods—including graphical processing, hydrogeochemical modeling, multivariate statistics and environmental isotopes—have been applied to a comprehensive dataset of physicochemical analyses and water level measurements. Results revealed that the initial hydrogeochemistry of groundwater was progressively impacted by secondary phenomena (e.g., ion exchange and redox reactions) which were clearly delineated into distinct zones according to data processing. The progressive evolution of groundwater was further verified by the variation of the saturation indices of critical minerals. In addition, the combined use of water level measurements delineated the major pathways of groundwater flow. Interestingly, the additional joint assessment of environmental isotopes revealed a new pathway from E–NE (which had never before been validated), thus highlighting the importance of the joint tools/methods application in complex scientific tasks. The application of multivariate statistics identified the dominant processes that control hydrogeochemistry and fit well with identified hydrodynamic mechanisms. These included (as dominant factor) the salinization impact due to the combined use of irrigation water return and evaporitic mineral leaching, as well as the impact of the geogenic calcareous substrate (mainly karstic calcareous formations and dolostones). Secondary factors, acting as processes (e.g., redox and ion exchange), were identified and found to be in line with initial assessment, thus validating the overall characterization. Finally, the outcomes may prove to be valuable in the progression toward sustainable groundwater resources management. The results have provided spatial and temporal information for significant parameters, sources, and processes—which, as a methodological approach, could be adopted in similar cases of other catchments.

Using single cell/filament PCR method for study non-cultured cyanobacteria

Cyanobacteria are photosynthetic prokaryotic organisms, and they are believed to be the Earth’s oldest life form. They were responsible for forming the oxygen on the Earth and from then they have been able to adapt to a multitude of environmental conditions, which allowing to be present in a wide range of habitats. When it comes to perform ecological and/or taxonomic studies one of problems which we must confront is the fact of some cyanobacteria are present in the nature in a few amounts, going unnoticed. Moreover, some of them show large mucilaginous sheaths, which making difficulted its isolation and growth later in culture. All these aspects have hindered the molecular assessment of a large portion of traditional cyanobacterial taxa, as Rivularia and Stigonema, especially necessary evaluation in the taxonomic studies. Rivularia genus grows on submerged stones, rocks, and damp soils near riverbanks, often on calcareous substrates and in clear, unpolluted, and streaming or stagnant waters, but also there are several species known from marine littoral. However, Stigonema genus grows aerophytically or subaerophytically on bark of trees or wet rocks, from lowland to the alpine zone of high mountains, but also several species are known from pools, swamps and moors. In this study, several Rivularia colonies collected in the Croatian Adriatic coast and several Stigonema species from Spanish alpine terrestrial environments are being analysed. The used methodology consists of a number of stages. In the first step, the samples are washed in EDTA disodium salt solution for dissolving the associated of calcium carbonate deposits (STEP 1). For the isolation of single cells and filaments, we are using a modified single filament isolation technique for planktonic cyanobacteria applying a glass capillary under sterile conditions (Zapomělová et al. 2008) described by Mareš et al. 2015 (STEP 2). Then, an optimized protocol we are utilized for amplification of the 16S rRNA gene, the associated 16S–23S internal transcribed spacer (ITS) region and the partially the 23S rRNA gene (2,000-2,500 bp) (Berrendero et al. 2016) (STEP 3). Finally, sequences analysis will carry out to determine the phylogenetic position of the different genotypes found inside a same Rivularia colony to be able to relation them with the morphotypes observed by the microscope. In the case of the Stigonema samples, we have successfully gotten the isolation of several filaments and, at the present, we are working on the amplification the studied region. This methodology, based on a glass capillary isolation technique and a PCR protocol for amplification of specific sequences, has been applied with success in the Rivularia and Stigonema samples without the need to cultivate them. Our future research will focus on the amplification of several taxonomic marker genes at the same time.

Natural Grasslands as Lignocellulosic Biofuel Resources: Factors Affecting Fermentable Sugar Production

Semi-natural grassland habitats are most often limited to animal grazing and low intensity farming. Their potential in bioenergy production is complicated due to the heterogeneity, variation, accessibility, and need for complex pre-treatment/hydrolysis techniques to convert into valuable products. In this research, fermentable sugar production efficiency from various habitats at various vegetation periods was evaluated. The highest fermentable sugar yields (above 0.2 g/g volatile solids) over a period of 3 years were observed from habitats “xeric and calcareous grasslands” (Natura 2000 code: 6120) and “semi-natural dry grasslands and scrubland facies on calcareous substrates” (Natura 2000 code: 6210). Both had a higher proportion of dicotyledonous plants. At the same time, the highest productivity (above 0.7 t sugar/ha) was observed from lowland hay meadows in the initial stage of the vegetation. Thus, despite variable yield-affecting factors, grasslands can be a potential resource for energy production.

Influence of application method and number of applications of nanolime on the effectiveness of the Doulting limestone treatments

Over the last two decades, nanolime has been recognized as a promising consolidation approach to consolidate historic calcareous substrates due to its compatibility, durability and fast carbonation. The effectiveness of nanolime products has been widely proven for superficial consolidation treatments, especially in historic wall-paintings. However, its consolidation mechanism in highly porous substrates, such as in the case of limestones or lime mortars, still needs to be fully understood. This paper aims to study the influence of application method and number of applications on the effectiveness of nanolime treatments, which has never been targeted until now. In this experimental work, the Ca(OH)2 nanoparticles were freshly synthetized by anion exchange resins and applied in historic Doulting limestone samples, extracted from a capital from the Cathedral of Wells (Somerset, UK). In order to study the influence of application method on the effectiveness of treatments, samples were treated by: (1) brush; (2) spray; and (3) capillary absorption. Additionally, to study the influence of the number of applications on the consolidation effectiveness, these three application methods were applied by: (1) 1 application; (2) 5 applications; (3) 10 applications. The consolidation effectiveness of the resulting nanolime treatments was studied by assessing changes in porosity, superficial and internal stone’s density, superficial cohesion, water absorption by capillarity and aesthetic properties. Results showed that repeated applications (i.e. 10 applications) of a low concentrated nanolime (i.e. 5 g/L) by spray and brush can increase the superficial cohesion, mechanical properties and density of the stone at the surface. Additionally, results suggest that the application method does not significantly affect the consolidation effectiveness of nanolime treatment, contrary to what was commonly believed. Results also show that a single application treatment of low concentrated nanolime (i.e. 5 g/L) does not significantly provide noticeable consolidation effectiveness regardless of the application method, also contrary to what was commonly believed. These results suggest that for a noticeable consolidation treatment with low concentrated nanolime the application must consist of several applications (> 10). This could have a high impact on the Built Heritage conservation community that commonly use nanolime in conservation activities.

Bacinella, a discrete type of Mesozoic calcimicrobial structure

The controversy surrounding Bacinella irregularis Radoičić, 1959, and Lithocodium aggregatum Elliott, 1956, has involved both sedimentologists and paleontologists. Arguments to exclude them from the Codiaceae are reviewed. The same arguments may be advanced to exclude their ascription to most other organisms. The only hypothesis resisting all elements of disproof is that of a consortium involving microbial communities. Accordingly, these structures are treated here as biosedimentary structures, namely bacinella structures, and not as taxa. One of the features specific to the organisms that built these structures is their strong corroding ability, as shown by the examples of fossils partly or fully cannibalized. This represents one state of corrosion beyond surficial etching and borings. Besides their capacity to corrode calcareous substrates, these microbial organisms formed nodules or oncoids and even built biostromes, which, depending on their stage of development, may have formed soft, firm or even hard substrates. However, to our knowledge, microbial communities contributing to bacinella structures never built up any bioherm. To complete this summary review, a building-block model that coherently takes into account most architectural variations is presented in the form of a figure sketch. The endolithic foraminifer Troglotella incrustans, which is commonly found associated with bacinella structures, is not an encruster or a borer. Lastly, contrary to certain erroneous hypotheses, no major bacinella episode has been ever found coeval with any significant Oceanic Anoxic Event.

Explaining the Atlas Cedar (Cedrus atlantica M.) dieback by studying Water relations of young plants subject to an edaphic drought

Cedrus atlantica M. stands from the Middle Atlas Mountains in Morocco have been severely affected by dieback. The edaphic water deficit could be the cause that triggered this phenomenon leading to the mortality of dying trees. The objective of this work is to analyze the ecophysiological behavior of Atlas cedar seedlings subjected to an edaphic drought of progressive intensity. During the drying cycle, the relative moisture content of the substrate decreased significantly to reach 12.71% at the end of the test; 4.27% and 2.88% respectively for the basaltic, calcareous, and sandy substrate. The pre-dawn water potential reached very low values of -32.25, -37.38, and -39.50 bar at the end of the water drying cycle. The critical water potential varied between -36 and -39 bar depending on the type of substrate. The mean maximum stomatal conductance under favorable water conditions was of the order of 330 mmol/m2/s. It was reduced, due to drying, in proportion to the reduction in substrate moisture content. Atlas cedar maintains gas exchange under conditions of severe water stress but can be lethal with extreme and recurrent droughts. This behavior can explain the development of the phenomenon of cedar stand decline, which is more accentuated especially with adverse ecological conditions.

Improvement of soil property mapping in the Great Clay Belt of northern Ontario using multi-source remotely sensed data

This study aimed to improve the accuracy in modelling the properties of forest soil by employing a variety of remotely sensed data. In addition to the commonly used multispectral satellite imagery, airborne LiDAR (light detection and ranging) data were exploited to derive detailed vegetation properties and topographic variables. Random forest (RF) and support vector machine (SVM) approaches were applied to classify soil types in terms of texture, calcareous substrate reaction to hydrochloric acid, and ELC (Ecological Land Classification) moisture regime. The developed methods were tested on data acquired over a boreal region (49° - 50° N, 81° - 84° W) with a combined area of 4,085 km2 in the Great Clay Belt (GCB) region, Ontario, Canada. Compared with the field-collected data, the overall accuracies and kappa coefficients of the retrieved soil properties were greater than 0.7 and 0.5, respectively. The accuracies attained between the RF and SVM approaches were similar, but in general the highest accuracies were achieved by the RF method. The models developed for the whole GCB regions generated accuracies comparable to those for the three sub-regions. The lowest modelling uncertainties occurred in areas dominated by peatland, whereas the highest modelling uncertainties existed in the regions with dry moisture regime or clayey soil at the surface. The results also showed that environmental covariates corresponding to vegetation were most important in the prediction of soil properties. Specifically, canopy height model (CHM) and gap fraction derived from LiDAR data, were among the most important variables.The inclusion of LiDAR-derived covariates demonstrated potential, applied in addition with topographic and climatic covariates and optical imagery. CHM pertains to the vertical dimension, and gap fraction relates to the density of the canopy layer, respectively; both covariates that offer supplemental detail that is not necessarily ascertained for the canopy by optical imagery.

Potential effects of the shape of gypsum aggregates on the early sulfation of marble and travertine

The damages caused by growth of gypsum crusts on calcareous substrates are well known. Sulfation of stones such as marble and travertine – used in constructions and Cultural Heritage – implies a structural and aesthetical weathering that leads, in time, to flaking, spalling and disruption. The effects of the initial gypsum growth and development were studied by simulating acid attacks on marble and travertine test specimens, evaluating the potential mechanical actions exerted by the shape of the newly grown aggregates. By monitoring the incipient sulfation with optical microscopy and SEM-EDS – backed up by XRPD, a peculiar growth sequence was confirmed: i) at first, tabular ‘Montmartre’ twins grow close and roughly parallel to the calcareous substrate; ii) later, a second generation of prismatic crystals grows on top of the former twins, in aggregates perpendicular to the calcareous matrix. When confined at the grain boundaries or within the narrow pores/fissures typical of marble and travertine textures, these gypsum overgrowths (basal platy twins topped by prismatic crystals) may exert strong crystallization pressures on the host carbonatic matrix, coupled to disjoining pressures granted by persistence of superficial liquid films at the host/guest interface. These phenomena cause the prismatic crystals, shielded by the older twins, to push away the facing calcareous matrix with a repulsive strength that, once the tensile strength is exceeded, brings to flaking, powdering, disruption and spalling. Strictly crystallographic aspects might thus concur to the early deterioration of calcareous substrates after sulfation, favouring mechanical actions that contribute to the damaging effects of gypsum crusts on the surface of buildings and Cultural Heritage in calcareous stones.

Plant communities and habitat types in the protected area of Lake Pamvotis (Epirus, Northwestern Greece)

The vegetation of the protected area of Lake Pamvotis (Epirus, NW Greece) was studied and classified into habitat types according to the Council Directive 92/43/EEC. The main vegetation types encountered in the Ioannina Basin and the south-western part of Mt Mitsikeli are: (1) Quercus coccifera shrublands, (2) degraded deciduous oak forests, (3) Mediterranean arborescent mattorals with Juniperus, (4) Oro-Mediterranean heathlands, (5) willow low open forests, (6) οriental plane woods, (7) plant communities supported by calcareous substrates, (8) aquatic macrophyte assemblages, (9) reed beds and rush meadows. Twenty plant communities belonging to twelve alliances, eleven orders, and ten phytosociological classes were discerned. The Asplenio ceterach-Aurinietum saxatilae is described as a new association and the Eleocharito palustris-Alismatetum lanceolati is reported for the first time from Greece. Eleven habitat types were identified and their conservation status was assessed. Three habitat types (4090, 8210, 91M0) were in favourable conservation status, while one (5210) is in unfavourable-bad conservation status. The rest are in unfavourable-inadequate conservation status, with several pressures and threats recorded.

THE FIRST EVIDENCE OF BIOEROSION IN CHITINOUS LACUSTRINE MICROFOSSILS FROM GLACIAL LAKES (LATE PLEISTOCENE AND HOLOCENE, BOHEMIAN FOREST)

ABSTRACT Microbioerosion structures are a common sign of microbial activity known mainly from marine environments and calcareous substrates, or from pollen records. However, the same phenomenon has been overlooked in animal fossils preserved in lake sediments. We studied 430 fragments of chitinous microfossils from three central European glacial lakes and detected microboring structures in approximately 10%. The microfossils belong to two size groups: (1) spherical objects with lengths ranging from 50 to 300 μm that are probably microturbelarian (Turbellaria: Rhabdocoela) cocoons, and (2) larger remnants (up to 2 mm long) of caddisfly (Insecta: Trichoptera) frontoclypeal apotomes. Four microbioerosion morphotypes were distinguished: (1) small holes (< 0.6 μm) oriented perpendicular to microfossil walls, likely produced by bacteria or fungi; (2) simple meandering tunnels and; (3) asterisk-like tunnel structures produced by fungi and/or fungus-like organisms; and (4) abrasions caused by biofilms. The maximum diameter of the simple holes and both tunnel structures depended on host-microfossil size: a higher diversity of microbioerosions was found on larger chitinous fragments. We propose that the good preservation of microfossils in the studied sediment samples might be due to rapid transport to the anoxic profundal zone or by rapid burial in anoxic sediments.

Temporal and spatial patterns of orchid species distribution in Greece: implications for conservation

Studies comparing species’ distribution range at different time periods provide valuable information about temporal trends, and may help to identify the factors responsible for these changes. This knowledge is vital for setting conservation priorities and applying suitable management strategies and practices focused on species’ conservation. We examined records produced before and after December 31, 1985 for determining possible changes in the distribution range of 195 orchid species recorded in Greece, using a 10 × 10 km grid as the recording unit. We used regression techniques to explore the association of species richness with environmental and spatial variables. Species richness was calculated by using the orchid records made (a) before December 31, 1985, (b) after January 1, 1986, and (c) in both time periods. Generalized linear models (GLM) were used for identifying the most significant factors associated with the distribution of the threatened orchids of Greece. Most Greek orchids showed an increasing trend in distribution from the first to the second period, with the exception of a few Critically Endangered species, whose distribution was larger in the first than in the second period. The spatial distribution of the threatened orchids was mostly explained by land area and the area of the calcareous substrates at each grid cell, whereas all variables that were used in the GLM analysis accounted for about 32% of the variance. The observed increasing trend in orchid distribution should be attributed to the extensive research efforts during the second period, especially in areas of high altitude and towards the northern parts of Greece. Our results did not support the findings of other studies, mainly from northern Europe, which showed a significant decline in the distribution range of their orchid flora. These differences in distribution trends could be attributed to the complex orographic configuration of Greece, which renders large parts of the country rather unsuitable for agricultural use or for extensive urban development.