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Sample records for calcicoles

  1. TILIA-DOMINATED CALCICOLOUS FORESTS IN THE CZECH REPUBLIC FROM A CENTRAL EUROPEAN PERSPECTIVE

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    M. CHYTRY

    1997-04-01

    Full Text Available The Seslerio albicantis-Tilietum cordatae is described as a new association of the calcicolous forests in the Czech Republic. It includes species-rich Tilia cordata or T. platyphyllos dominated forests with a mixture of mesophilous forest species and thermophilous oak-forest species in the field layer, confined to shallow soils of the upper slopes. During the postglacial period, these forests probably developed from Sesleria albicans-grassland and Corylus avellana-scrub and preserved a number of relict species. Comparative analysis of selected literature data on Central European calcicolous forests dominated by Tilia species yielded 6 major floristically defined groups and a few communities of local importance. These groups include: (1 Asperulo taurinae-Tilietum of Swiss föhn valleys, (2 Aceri-Tilietum of central and southern Germany and NW Switzerland, (3 Aceri-Carpinetum aconitetosum vulpariae of the Czech Republic (nutrient-rich habitats, (4 Seslerio albicantis-Tilietum cordatae of the Czech Republic (nutrient-poor habitats, (5 Mercuriali-Tilietum of the Hungarian Central Range, (6 Tilio- Fraxinetum excelsioris of the Carpathian fringes in Hungary and Romania.

  2. TILIA-DOMINATED CALCICOLOUS FORESTS IN THE CZECH REPUBLIC FROM A CENTRAL EUROPEAN PERSPECTIVE

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    J. SADLO

    1997-01-01

    Full Text Available The Seslerio albicantis-Tilietum cordatae is described as a new association of the calcicolous forests in the Czech Republic. It includes species-rich Tilia cordata or T. platyphyllos dominated forests with a mixture of mesophilous forest species and thermophilous oak-forest species in the field layer, confined to shallow soils of the upper slopes. During the postglacial period, these forests probably developed from Sesleria albicans-grassland and Corylus avellana-scrub and preserved a number of relict species. Comparative analysis of selected literature data on Central European calcicolous forests dominated by Tilia species yielded 6 major floristically defined groups and a few communities of local importance. These groups include: (1 Asperulo taurinae-Tilietum of Swiss föhn valleys, (2 Aceri-Tilietum of central and southern Germany and NW Switzerland, (3 Aceri-Carpinetum aconitetosum vulpariae of the Czech Republic (nutrient-rich habitats, (4 Seslerio albicantis-Tilietum cordatae of the Czech Republic (nutrient-poor habitats, (5 Mercuriali-Tilietum of the Hungarian Central Range, (6 Tilio- Fraxinetum excelsioris of the Carpathian fringes in Hungary and Romania.

  3. Historical divergence versus contemporary gene flow: evolutionary history of the calcicole Ranunculus alpestris group (Ranunculaceae) in the European Alps and the Carpathians

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    Paun, O.; Schönswetter, P.; Winkler, M.; Tribsch, A.

    2010-01-01

    Although many species have similar total distributional ranges, they might be restricted to very different habitats and might have different phylogeographic histories. In the European Alps, our excellent knowledge of the evolutionary history of silicate-dwelling (silicicole) plants is contrasted by a virtual lack of data from limestone-dwelling (calcicole) plants. These two categories exhibit fundamentally different distribution patterns within the Alps and are expected to differ strongly with respect to their glacial history. The calcicole Ranunculus alpestris group comprises three diploid species of alpine habitats. Ranunculus alpestris s. str is distributed over the southern European mountain system, while R. bilobus and R. traunfellneri are Southern Alpine narrow endemics. To explore their phylogenetic relationships and phylogeographic history, we investigated the correlation between information given by nuclear and chloroplast DNA data. Analyses of AFLP fingerprints and matK sequences gave incongruent results, indicative for reticulate evolution. Our data highlight historical episodes of range fragmentation and expansion, occasional long distance dispersal and on-going gene flow as important processes shaping the genetic structure of the group. Genetic divergence, expressed as a rarity index (“frequency-down-weighted marker values”) seems a better indicator of historical processes than patterns of genetic diversity, which rather mirror contemporary processes as connectivity of populations and population sizes. Three phylogeographical subgroups have been found within the R. alpestris group, neither following taxonomy nor geography. Genetic heterogeneity in the Southern Alps contrasts with Northern Alpine uniformity. The Carpathians have been stepwise colonised from the Eastern Alpine lineage resulting in a marked diversity loss in the Southern Carpathians. The main divergence within the group, separating the ancestor of the two endemic species from R

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

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    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.

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

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    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

  6. Lithologic data improve plant species distribution models based on coarse-grained occurrence data

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    Gaston, A.; Soriano, C.; Gomez-Miguel, V.

    2009-07-01

    The aim of this study was to assess the improvement of plant species distribution models based on coarse-grained occurrence data when adding lithologic data to climatic models. The distributions of 40 woody plant species from continental Spain were modelled. A logistic regression model with climatic predictors was fitted for each species and compared to a second model with climatic and lithologic predictors. Improvements on model likelihood and prediction accuracy on validation sub samples were assessed, as well as the effect of calcicole calcifuge habit on model improvement. Climatic models had reasonable mean prediction accuracy, but adding lithologic data improved model likelihood in most cases and increased mean prediction accuracy. Therefore, we recommend utilizing lithologic data for species distribution models based on coarse-grained occurrence data. Our data did not support the hypothesis that calcicole calcifuge habit may explain model improvement when adding lithologic data to climatic models, but further research is needed. (Author) 31 refs.

  7. Investigation on soil organic component and its relationships with silvicultural regime in beechwoods (Trento, Italy

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    Cason D

    2008-03-01

    Full Text Available Since the last 50 years, areas where beech coppices remain unmanaged are increasing in Italy. In more recent years some of these coppices underwent conversion to high-forest. Little information exists on the consequences of this management choice for ecosystem properties, such as soil organic matter and soil humic substances. This study consists in a quantitative and qualitative characterization of soil organic matter as a function of different management and pedoclimatic conditions in beech coppices in Trentino, Northern Italy. The study was conducted in four beech coppices, two calcicolous mesic typical beech forests and two calcicolous xeric beech forests. For each forest type we selected one unmanaged coppice (over the last 40 years and one coppice stand converted to high forest by releasing a limited number of standards. The qualitative features of humic substances were examined through gel-filtration and Diffuse Reflectance Infra Red Spectroscopy. Results show that the two types of forest respond in a different way to the conversion treatment. In mesic beech forest, humification parameters appear to slow down after silvicultural treatment; in xeric beech forest, a stronger polycondensation of humic compounds was observed after the silvicultural treatment.

  8. Revision of monotypic genus Llavea (Cryptogrammoideae: Pteridaceae

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    Mónica Palacios-Rios

    2016-12-01

    Full Text Available Llavea Lag. is a genus of Cryptogrammoideae (Pteridaceae, whose only species is distributed from southern United States and Mexico to Guatemala and Costa Rica, although it lives mainly in Mesoamerica, inhabiting preferably calcicolous habitats associated with forests and mountains. The genus is easily recognized by the presence of fertile leaves hemi-dimorphic, with the fertile apical portion with longer and narrower segments than the sterile ones, with strongly revolute margin, and rhizome scales bicolorous, shiny, and black. This paper presents a revision of the genus, nomenclatural issues are resolved, and and palynological morphological diversity are reviewed, as well as its distribution, phenology, ecology, and applications, based on field and herbarium specimens studies. In addition, two names related to Llavea, Allosorus karwinskii Kunze and Ceratodactylis osmundioides J. Sm., were lectotypified.

  9. Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula

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    Martin eVenturas

    2014-03-01

    Full Text Available The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (U. minor and siliceous (U. laevis soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during six weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H+ extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. Ulmus minor had a higher root ferric reductase activity and H+-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different iron acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.

  10. Adaptive strategies of Parietaria diffusa (M.&K.) to calcareous habitat with limited iron availability.

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    Donnini, Silvia; De Nisi, Patrizia; Gabotti, Damiano; Tato, Liliana; Zocchi, Graziano

    2012-06-01

    The study of native plants growing in hostile environments is useful to understand how these species respond to stress conditions. Parietaria diffusa (M.&K.) is able to survive in highly calcareous soils and extreme environments, such as house walls, without displaying any chlorotic symptoms. Here, we have investigated the existence of Strategy I complementary/alternative mechanism(s) involved in Fe solubilization and uptake and responsible for Parietaria's extraordinary efficiency. After assessing the specific traits involved in a calcicole-behaviour in the field, we have grown plants in conditions of Fe deficiency, either direct (-Fe) or induced by the presence of bicarbonate (+FeBic). Then, the growth performance, physiological and biochemical responses of the plants were investigated. The study shows that in Parietaria+FeBic, the classical responses of Strategy I plants are activated to a lower extent than in -Fe. In addition, there is a greater production of phenolics and organic acids that are both exuded and accumulated in the roots, which in turn show structures similar to 'proteoid-like roots'. We suggest that in the presence of this constraint, Parietaria undergoes some metabolic rearrangements that involve PEP-consuming reactions and an enhancement of the shikimate pathway. © 2012 Blackwell Publishing Ltd.

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

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    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. Copyright 1999 Academic Press.

  12. 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)

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    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.

  13. Grassland habitat restoration: lessons learnt from long term monitoring of Swanworth Quarry, UK, 1997–2014

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    Barbara Maria Smith

    2017-11-01

    Full Text Available Habitat restoration projects are often conducted when prior use or extraction of natural resources results in land degradation. The success of restoration programmes, however, is variable, and studies that provide evidence of long term outcomes are valuable for evaluation purposes. This study focused on the restoration of vegetation within a limestone quarry in Dorset, UK between 1997 and 2014. Using a randomised block design, the effect of seed mix and seed rate on the development of community assemblage was investigated in comparison to a nearby target calcareous grassland site. We hypothesised that seed mix composition and sowing rate would influence both the trajectory of the grassland assemblage and final community composition. We found that species composition (in relation to both richness and community assemblage was strongly influenced by time and to some extent by seed rate and seed mix. However, no treatments achieved strong resemblance to the calcareous grassland target vegetation; rather they resembled mesotrophic communities. We conclude that (as with previous studies there is no “quick fix” for the establishment of a grassland community; long-term monitoring provides useful information on the trajectory of community development; sowing gets you something (in our case mesotrophic grassland, but, it may not be the target vegetation (e.g., calcicolous grassland you want that is difficult to establish and regenerate; it is important to sow a diverse mix as subsequent recruitment opportunities are probably limited; post-establishment management should be explored further and carefully considered as part of a restoration project.

  14. Assembly Processes under Severe Abiotic Filtering: Adaptation Mechanisms of Weed Vegetation to the Gradient of Soil Constraints

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    Nikolic, Nina; Böcker, Reinhard; Kostic-Kravljanac, Ljiljana; Nikolic, Miroslav

    2014-01-01

    Questions 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? Location Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate. Methods 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). Results 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. Conclusion 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

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

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    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

  16. Diverse spore rains and limited local exchange shape fern genetic diversity in a recently created habitat colonized by long-distance dispersal.

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    De Groot, G A; During, H J; Ansell, S W; Schneider, H; Bremer, P; Wubs, E R J; Maas, J W; Korpelainen, H; Erkens, R H J

    2012-04-01

    Populations established by long-distance colonization are expected to show low levels of genetic variation per population, but strong genetic differentiation among populations. Whether isolated populations indeed show this genetic signature of isolation depends on the amount and diversity of diaspores arriving by long-distance dispersal, and time since colonization. For ferns, however, reliable estimates of long-distance dispersal rates remain largely unknown, and previous studies on fern population genetics often sampled older or non-isolated populations. Young populations in recent, disjunct habitats form a useful study system to improve our understanding of the genetic impact of long-distance dispersal. Microsatellite markers were used to analyse the amount and distribution of genetic diversity in young populations of four widespread calcicole ferns (Asplenium scolopendrium, diploid; Asplenium trichomanes subsp. quadrivalens, tetraploid; Polystichum setiferum, diploid; and Polystichum aculeatum, tetraploid), which are rare in The Netherlands but established multiple populations in a forest (the Kuinderbos) on recently reclaimed Dutch polder land following long-distance dispersal. Reference samples from populations throughout Europe were used to assess how much of the existing variation was already present in the Kuinderbos. A large part of the Dutch and European genetic diversity in all four species was already found in the Kuinderbos. This diversity was strongly partitioned among populations. Most populations showed low genetic variation and high inbreeding coefficients, and were assigned to single, unique gene pools in cluster analyses. Evidence for interpopulational gene flow was low, except for the most abundant species. The results show that all four species, diploids as well as polyploids, were capable of frequent long-distance colonization via single-spore establishment. This indicates that even isolated habitats receive dense and diverse spore rains

  17. Direct effect of acid rain on leaf chlorophyll content of terrestrial plants in China.

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    Du, Enzai; Dong, Dan; Zeng, Xuetong; Sun, Zhengzhong; Jiang, Xiaofei; de Vries, Wim

    2017-12-15

    Anthropogenic emissions of acid precursors in China have resulted in widespread acid rain since the 1980s. Although efforts have been made to assess the indirect, soil mediated ecological effects of acid rain, a systematic assessment of the direct foliage injury by acid rain across terrestrial plants is lacking. Leaf chlorophyll content is an important indicator of direct foliage damage and strongly related to plant productivity. We synthesized data from published literature on experiments of simulated acid rain, by directly exposing plants to acid solutions with varying pH levels, to assess the direct effect of acid rain on leaf chlorophyll content across 67 terrestrial plants in China. Our results indicate that acid rain substantially reduces leaf chlorophyll content by 6.71% per pH unit across the recorded plant species. The direct reduction of leaf chlorophyll content due to acid rain exposure showed no significant difference across calcicole, ubiquist or calcifuge species, implying that soil acidity preference does not influence the sensitivity to leaf injury by acid rain. On average, the direct effects of acid rain on leaf chlorophyll on trees, shrubs and herbs were comparable. The effects, however varied across functional groups and economic use types. Specifically, leaf chlorophyll content of deciduous species was more sensitive to acid rain in comparison to evergreen species. Moreover, vegetables and fruit trees were more sensitive to acid rain than other economically used plants. Our findings imply a potential production reduction and economic loss due to the direct foliage damage by acid rain. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. 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

  19. 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.

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

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    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

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

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    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

  2. 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.

  3. 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 (