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Sample records for calcicoles

  1. Revue bibliographique sur la restauration des pelouses calcicoles en Europe : contraintes rencontrées et solutions proposées

    OpenAIRE

    Piqueray, Julien; Mahy, Grégory

    2010-01-01

    Les pelouses calcicoles, qui sont considérées comme des hotspots de biodiversité en Europe, ont subi un fort déclin durant le siècle dernier. Dès lors, il est apparu que la restauration de ces habitats s’imposait en tant que stratégie de conservation. La restauration consiste à recréer les conditions biotiques et abiotiques permettant aux espèces typiques de s’installer. En fonction du type de dégradation du milieu, plusieurs contraintes peuvent survenir lors de la restauration, comme l’enric...

  2. Aspects de l'ornithochorie et de la germination des semences des arbustes en fruticée calcicole de Calestienne

    OpenAIRE

    Éthel Dupont; François Malaisse; Jean-François Dulière

    1997-01-01

    Dispersai by birds and germination of seeds from some scrubs in a calcareous shrublandThe thorny shrubland is the mort common évolution stage of ungrazed calcareous grasslands in Western Europe. Shrubs of this thicket bear many fruits which are especially dispersed by birds, according to différent feeding behaviours. Regarding the phenology of the main species, ripe fruits are available during nearly eight months. Some germination tests have been applied to seeds with intention to break possi...

  3. Aspects de l'ornithochorie et de la germination des semences des arbustes en fruticée calcicole de Calestienne

    Directory of Open Access Journals (Sweden)

    Éthel Dupont

    1997-01-01

    Full Text Available Dispersai by birds and germination of seeds from some scrubs in a calcareous shrublandThe thorny shrubland is the mort common évolution stage of ungrazed calcareous grasslands in Western Europe. Shrubs of this thicket bear many fruits which are especially dispersed by birds, according to différent feeding behaviours. Regarding the phenology of the main species, ripe fruits are available during nearly eight months. Some germination tests have been applied to seeds with intention to break possible dormancy phenomenon. The seed of Ligustrum vulgare L. can germinale without any pretreatment. For Prunus spinosa L. and Rhamnus cathartica L., a cold period is required to break dormancy. Other species, like Rosa canina L., or Crataegus monogyna Jacq., demand spécial treatment to break complex dormancies. The role of frugivores seems more to pull down the pulp of the fruit than to break dormancy by passage into digestive system.

  4. AMMONIUM TOXICITY AND NITRATE RESPONSE OF AXENICALLY GROWN DACTYLORHIZA-INCARNATA SEEDLINGS

    NARCIS (Netherlands)

    DIJK, E; ECK, N

    1995-01-01

    The response to ammonium- and nitrate-nitrogen of seedlings of the calcicole orchid species Dactylorhiza incarnata (L.) Soo was tested in axenic in vitro culture of c. 3-month-old protocorms. A pronounced toxicity of ammonium ions was observed. Seedlings raised from plants of a coastal population (f

  5. Are Fe and P availabilities involved in determining the occurrence and distribution of Calluna vulgaris (L.) Hull in semi-arid grasslands on calcareous soils?

    OpenAIRE

    Fühner, Christoph; Runge, Michael

    2008-01-01

    Calluna vulgaris (L.) Hull is primarily found on acid soils and is generally classified as a calcifuge species. Therefore, its occasional growth in semi-arid grassland on shallow calcareous soils gave rise to the question as to whether special soil conditions, deviating from the typical conditions in calcareous soils, enable this unusual occurrence. In an attempt to answer this question, we analysed selected soil factors, comparing plots where C. vulgaris was growing besides calcicole species...

  6. The root ferric-chelate reductase of Ceratonia siliqua (L.) and Poncirus trifoliata (L.) Raf. responds differently to a low level of iron

    OpenAIRE

    Pestana, M; Gama, Florinda; Saavedra, Teresa; de Varennes, Amarilis; P.J. Correia

    2012-01-01

    Iron (Fe) deficiency is a common nutritional disorder in several crops grown in calcareous soils, but some species are well adapted to these conditions. A hydroponic experiment was conducted to compare the response of a calcicole species Ceratonia siliqua L. (carob) and of Poncirus trifoliata (L.) Raf., a citrus rootstock very sensitive to Fe deficiency. Rootstocks from both species were grown in nutrient solutions without Fe (0 M Fe), with 1 M Fe, and with 10 M Fe (carob) or 4...

  7. Principles and practices of countermeasures to be carried out following radioactive contamination of forest areas

    International Nuclear Information System (INIS)

    An earlier article featured a comprehensive list of specific measures aimed at reducing radiation levels within forest ecosystems. All these measures were assessed globally in terms of their expected effectiveness and practical limitations. This study considers the same measures but focuses on differences between three widely distributed forest ecosystems in Europe: Mediterranean calcicolous evergreen forest, temperate mesotrophic deciduous forest and boreal acidophilous coniferous forest. From this analysis, it emerges that the relatively wide range of countermeasures which, in theory, could be applied to forest ecosystems is much more limited when considering specific ecosystems and the variation between ecosystems

  8. Phylogenetic relationships of the silver saxifrages (Saxifraga, sect. Ligulatae haworth): implications for the evolution of substrate specificity, life histories, and biogeography.

    Science.gov (United States)

    Conti, E; Soltis, D E; Hardig, T M; Schneider, J

    1999-12-01

    The silver saxifrages (Saxifraga sect. Ligulatae Haworth; Saxifragaceae) exhibit remarkable variation of substrate specialization, with strictly calcicole to calcifuge species, as well as life histories which range from semelparity to iteroparity. They occur almost exclusively in the European mountain ranges and display high levels of endemism. Sequences from chloroplast and nuclear ribosomal DNA were obtained to resolve phylogenetic relationships among the silver saxifrages and related taxa and to gain insight into the evolution of substrate specificity, life history, and biogeography. The resulting phylogenies suggested that (1) Saxifraga sect. Ligulatae, as traditionally defined, does not constitute a monophyletic group; (2) lime-secreting hydathodes in calcifuge species apparently represent a secondary nonaptation; (3) semelparity evolved independently two or three times in the silver saxifrages and allied sections, possibly in response to climatic changes that occured during the Pleistocene; and (4) narrow endemics, for example S. cochlearis, likely evolved from the fragmentation of the widespread S. paniculata into refugial populations that became isolated during the glacial maxima of the Pleistocene. PMID:10620412

  9. Lichenometric age measured on rock-falls related to historic seismicity affecting Lorca and its surroundings (Murcia, SE Spain); Datacion mediante liquenometria de los desprendimientos rocosos asociados a la sismicidad historica en Lorca (Murcia, SE de Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, R.; Martin-Gonzalez, F.; Martinez-Diaz, J. J.; Rodriguez-Pascua, M. A.

    2012-11-01

    During the earthquake at Lorca (Murcia, SE Spain) in 2011 (5.2 Mw, 4km depth) several rock-falls occurred, mobilizing an estimated volume of close to 2,000 m3. All these rock-falls took place within the Estancias and La Tercia mountain ranges, the topography of which is composed of Tortonian calcarenitic sandstones with steep scarps more than 30 m in height. We have conducted a lichenometric study to obtain the age of the ancient rock-falls within the Las Estancias Range. We have assumed an annual growth rate of 0.24 mm for lichen species classified as calcicolous and related to warm climatic conditions. Our aim was to corroborate the hypothesis that seismic events triggered these massive rock-falls. The city of Lorca had experienced two nearfield historic earthquakes (1674 EMS VIII and 1818 EMS VI) and one far-field tremor during the great Lisbon earthquake in 1755 (EMS VI). Results obtained here indicate that the earthquakes of 1674 and 2011 were quite similar, except that the 1674 one mobilised a greater quantity and twenty times the volume of blocks mobilised during the 2011 earthquake. Therefore, we conclude that the size of the earthquake of 1674 was possibly between 6.0 < M < 6.8, assuming similar focal and seismotectonic conditions to those of the instrumentally measured earthquake of 2011. (Author) 34 refs.

  10. Assembly processes under severe abiotic filtering: adaptation mechanisms of weed vegetation to the gradient of soil constraints.

    Directory of Open Access Journals (Sweden)

    Nina Nikolic

    Full Text Available Effects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response?Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate.We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils over short distances (field scale.The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.Using annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically

  11. Inter-and intraspecific variation in fern mating systems after long-distance colonization: the importance of selfing

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    de Groot G Arjen

    2012-01-01

    Full Text Available Abstract Background Previous studies on the reproductive biology of ferns showed that mating strategies vary among species, and that polyploid species often show higher capacity for self-fertilization than diploid species. However, the amount of intraspecific variation in mating strategy and selfing capacity has only been assessed for a few species. Yet, such variation may have important consequences during colonization, as the establishment of any selfing genotypes may be favoured after long-distance dispersal (an idea known as Baker's law. Results We examined intra-and interspecific variation in potential for self-fertilization among four rare fern species, of which two were diploids and two were tetraploids: Asplenium scolopendrium (2n, Asplenium trichomanes subsp. quadrivalens (4n, Polystichum setiferum (2n and Polystichum aculeatum (4n. Sporophyte production was tested at different levels of inbreeding, by culturing gametophytes in isolation, as well as in paired cultures with a genetically different gametophyte. We tested gametophytes derived from various genetically different sporophytes from populations in a recently planted forest colonized through long-distance dispersal (Kuinderbos, the Netherlands, as well as from older, less disjunct populations. Sporophyte production in isolation was high for Kuinderbos genotypes of all four species. Selfing capacity did not differ significantly between diploids and polyploids, nor between species in general. Rather selfing capacity differed between genotypes within species. Intraspecific variation in mating system was found in all four species. In two species one genotype from the Kuinderbos showed enhanced sporophyte production in paired cultures. For the other species, including a renowned out crosser, selfing capacity was consistently high. Conclusions Our results for four different species suggest that intraspecific variation in mating system may be common, at least among temperate calcicole

  12. Caracterização nutricional do nim em plantios no Brasil Nutritional characterization of neem plantations in Brazil

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    Edinelson J. M. Neves

    2013-01-01

    data. The leaf sampling of neem trees, when realized in the middle of the crown subdivided in FCMS and FCMI depends, among other factors, on the nutrient mobility and on the light conditions of the stand. The leaf contents of Ca show indications that the neem plant could be a calcicole plant, and efficient in N and P absorption. The soil K content is positively correlated with the K content of the FCMI position.

  13. Variação intraespecífica dos nutrientes em folhas de Methodorea pubescens (Rutaceae em dois tipos de mata do Distrito Federal

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    Marcelo Trindade Nascimento

    1990-01-01

    were higher in the mature leaves. The concentration of P decreased from mature leaves to senescent leaves. The plants from calcareous soil showed higher concentration of Ca and lower concentration of K than plants of acidic soil. The values of P, Mg and Al were similar in both forests. The differences between populations could possibly be explained by soil type, but other factors such as the physiological behavior of plants should also be considered. Plants from the acidic soil can be calcifuge and plants from the calcareous soil can be calcicole.

  14. An investigation on the resources of wild shade ornamental plants in Guangxi%广西野生阴生观赏植物资源及其特点

    Institute of Scientific and Technical Information of China (English)

    蒋能; 宁世江; 盘波; 沈晓琳; 黄仕训

    2012-01-01

    In order to understand the wild and shade ornamental plant resources and valuable germplasm hidden in Guangxi,the shade and half shade plant resources in Guangxi were studied by the methods of field investigation and specimen collection identification. The results showed that the five basic characteristics of Guangxi wild shade ornamental plants: rich species(162 families, 485 genera, and 1 309 species) , precious germplasm resources (including 195 species of the valuable and rare plant, and 136 species endemic to Guangxi) , diversity of growth soil texture (the calcicole, the acidophile and the intermediate plant), remarkable of the herbaceous ratio(the herb plants account for about 66. 1%) ,and great disparity of wild resources distribution. The six taxa were as following:Pteridophyte(43 families,240 species) ,Orchidaceae(37 genera,126 species) ,Liliaceae(21 genera,82species) ,Gesneriaceae(17 genera, 63 species) ,Begoniaceae(l genera,43 species) and Araceae(12 genera,30 species). The results would provide a reference for the rational development and u-tilization of wild shade ornamental plant resources.%为了解广西境内蕴藏的野生阴生观赏植物资源及珍贵种质,采取野外实地考察及标本采集鉴定相结合的方法,对广西全境分布的阴生和半阴生观赏植物资源进行研究.结果表明:广西野生阴生观赏植物有5个基本特点:种类丰富(162科485属1 309种)、种质资源珍贵(珍稀植物195种,广西特有植物136种)、生长基质多样(喜钙植物、喜酸植物和中间类型植物)、草本性状比值显著(草本植物约占总种数的66.1%)、野生资源贮藏量的多寡悬殊性.6个主要野生阴生观赏类群为:蕨类植物(43科240种)、兰科(37属126种)、百合科(21属82种)、苦苣苔科(17属63种)、秋海棠科(1属43种)、天南星科(12属30种).研究结果可为合理开发利用广西野生阴生观赏植物资源提供参考.

  15. Experimental identification of mechanisms controlling calcium isotopic fractionations by the vegetation.

    Science.gov (United States)

    Cobert, Florian; Schimtt, Anne-Désirée.; Bourgeade, Pascale; Stille, Peter; Chabaux, François; Badot, Pierre-Marie; Jaegler, Thomas

    2010-05-01

    This study aims to better understand the role of vegetation on the Ca cycle at the level of the critical zone of the Earth, in order to specify the mechanisms controlling the Ca absorption by plants at the rock/plant interface. To do this, we performed experiments using hydroponic plant cultures in a way that we could control the co-occuring geochemical and physiological process and determine the impact of the nutritive solution on the Ca cycle within plants. A dicotyledon and calcicole plant with rapid growth, the French bean (Phaseolus vulgaris L.), has been chosen to have access to one complete growth cycle. Several experiments have been conducted with two Ca concentrations, 6 (L) and 60 (H) ppm and two pH values (4 and 6) in the nutritive solution, for which the Ca concentration was maintained constant, so its Ca content is considered as infinite. A second experiment (non infinite L6) allowed Ca depletion in the solution through time; therefore, response effects on the Ca isotopic signatures in the plant organs and in the nutritive solution were observed. We determined Ca concentrations and isotopic ratios in the nutritive solution and in different organs (main roots, secondary roots, old and young stems, old and young leaves and fruits) at two different growth stages (10 days and 6 weeks). Preliminary results show that: (1) the roots (main and secondary) were enriched in the light isotope (40Ca) compared to the nutritive solution, and leaves were enriched in the heavy isotope (44Ca) compared to stems. These results are in accord with previously published field studies (Wigand et al., 2005; Page et al., 2008; Cenki-Tok et al., 2009; Holmden and Bélanger, 2010). Leaves and secondary roots were however enriched in the heavy isotope (44Ca) compared to bean pods, stems and main roots. These results could be related to kinetic fractionation processes occurring either during the Ca root uptake, or during the Ca transport within the plant, or physiological mechanisms

  16. Potential of calcium isotopes to identify fractionations in vegetation: experimental approach

    Science.gov (United States)

    Cobert, F.; Schmitt, A.; Bourgade, P.; Stille, P.; Chabaux, F. J.; Badot, P.; Jaegler, T.

    2010-12-01

    This study aims to better understand the role of vegetation on the Ca cycle at the level of the critical zone of the Earth, in order to specify the mechanisms controlling the Ca absorption by plants at the rock/plant interface. To do this, we performed experiments using hydroponic plant cultures in a way that we could control the cooccuring geochemical and biological processes and determine the impact of the nutritive solution on the Ca cycle within plants. A dicotyledon and calcicole plant with rapid growth, the French bean (Phaseolus vulgaris L.), has been chosen to have access to one complete growth cycle. Several experiments have been conducted with two Ca concentrations, 5 (L) and 60 (H) ppm and two pH values (4 and 6) in the nutritive solution, for which the Ca concentration was maintained constant, so its Ca content is considered to be infinite. We determined Ca concentrations and isotopic ratios in the nutritive solution and in different organs (main roots, secondary roots, old and young stems, old and young leaves and fruits) at two different growth stages (10 days and 6 weeks). Our results show, in accord with previously published field studies, that the bean organs are all enriched in the light 40Ca isotope compared to the nutritive solution (e.g. Wigand et al., 2005; Page et al., 2008; Cenki-Tok et al., 2009; Holmden and Bélanger, 2010). We identify two fractionation levels. The first occurs during the uptake of the nutrient elements by the lateral roots. This implies that the main mechanisms of light isotope enrichments in the plant are due to electrochemical gradient transport processes taking place at this interface. The second fractionation can be observed within the plant itself and is due to the nature of the considered organ itself. Indeed structural reservoirs (primary roots, stem, reproductive organs) incorporate more the light 40Ca isotope compared to the transfer reservoirs (lateral roots, xylem sap, leaves). This could be linked to ion

  17. La transición mediterráneo-eurosiberiana en Navarra: caracterización de los tomillares y aliagares su mediterráneos (Thymelaeo-Aphyllanthetum monspeliensis

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    Peralta, J.

    2001-12-01

    Full Text Available Structure, flora, ecology and dynamics of submediterranean Thymus vulgaris garrigues (Thymelaeo-Aphyllanthetum monspeliensis are analysed and compared with two groups of calcicolous scrubs, based upon 391 relevés from Navarre (NE Spain. Those submediterranean Thymus vulgaris garrigues are more diverse, have higher proportion of hemicryptophytes than cushion heaths of Genista occidentalis (Genistion occidentalis and show wide ecological differences, as they thrive at lower altitudes, on less inclined slopes with preference for southward exposures. They are distinguished from the more xerophillous somontano-aragonés Thymus vulgaris garrigues (Aphyllanthion by their higher frequency of Atlantic and Eurosiberian taxa, lower proportion of nano-phanerophytes and affinity for more humid climates. There is a gradual change in the flora and structure of those three scrub groups related with the Eurosiberian-mediterranean climatic transition. Thymelaeo-Aphyllanthetum floristic composition has higher frequency of character taxa of Rosmarinetea and Rosmarinetalia than those of Festuco-Ononidetea striatae and Ononidetalia striatae, and this feature together with its structure justify the inclusion of this community in Aphyllanthion alliance, pointing out their relationship with somontano-aragonés Thymus vulgaris garrigues.

    [fr]
    Sur la base de 391 rélevés procédant de la Navarre, les auteurs ont analysé les caractères physionomiques, floristiques, dynamiques et écologiques des garrigues subméditérranéennes (Thymelaeo-Aphyllanthetum monspeliensis et ont établi également la comparaison avec d'autres types de matorral basophiles. Ainsi les garrigues du Thymelaeo-Aphyllanthetum se montrent plus diverses et avec un pourcentage d'hemicryptophytes plus élevé que celui de la lande à Genista occidentalis (