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Détail de l'auteur
Auteur Hendrik Schubert |
Documents disponibles écrits par cet auteur
Affiner la rechercheBiogeography of Chilean Charophytes – determined by climate or by water chemistry ? / Hendrik Schubert in Botany letters, vol. 165, n°1 (Année 2018)
Titre : Biogeography of Chilean Charophytes – determined by climate or by water chemistry ? Type de document : Livre Auteurs : Hendrik Schubert, Auteur ; I. Blindow, Auteur ; M. Mages, Auteur ; W. von Tÿmpling, Auteur ; S. Woelfl, Auteur Année de publication : 2018 Article en page(s) : pp. 129-145 Langues : Anglais Catégories : [ZG] Chili
[Thèmes] Charophytes / CharacéesMots-clés : Chara Nitella Résumé : "Distinct distribution patterns were observed for several species of charophytes during a survey in Chile. We attempted to link these patterns to climatic conditions, but no direct causality between specific climatic factors and charophyte growth conditions could be identified. In this paper, correlations between water chemistry and occurrence of charophytes were tested as an alternative approach to explain the distribution pattern. Datasets with information about conductivity, alkalinity, pH and concentrations of calcium, magnesium, sodium, potassium, sulphate and chloride from sites inhabited by at least one charophyte species were analysed by principal component analysis. The results show that the distribution patterns of at least some species can be explained by niche differences with respect to water chemistry. The genera Chara and Nitella are in general well separated by their preferences for a given pH, alkalinity and conductivity range. Within the genus Chara, Chara squamosa, Chara braunii, Chara fulgens, and a yet unidentified taxon Chara sp., differ from this genus-specific pattern with respect to at least one parameter, whereas Chara vulgaris occupies a broad niche, covering almost the full range of all parameters except conductivity. Within the genus Nitella, niche separation by water chemistry was only possible between Nitella tenuissima and Nitella asagrayana. The chemical niche of Chara braunii was more closely related to the niche of the genus Nitella than the niche of other Chara species." (source : auteurs) Type de publication : périodique Référence biblio : Schubert H., Blindow I., Mages M., von Tÿmpling W., Woelfl S., 2018 - Biogeography of Chilean Charophytes – determined by climate or by water chemistry ? Botany letters, 165 (1) : 129-145. ID PMB : 67242 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67242
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 129-145[article]Exemplaires
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Titre : Diaspore bank analysis of Baltic coastal waters Type de document : Livre Auteurs : Petra Nowak, Auteur ; Tim Steinhardt, Auteur ; Ulla Von Ammon, Auteur ; Henning Rohde, Auteur ; Arne Schoor, Auteur ; Anja Holzhausen, Auteur ; Ralf Schaible, Auteur ; Hendrik Schubert, Auteur Année de publication : 2018 Article en page(s) : pp. 159-173 Langues : Anglais Catégories : [habitats/milieux] 1 - Habitats littoraux et halophile
[Thèmes] Charophytes / CharacéesMots-clés : eutrophisation restauration germination diaspore oospore Résumé : "The coastal waters are important transition zones for terrestrial nutrient and pollutant runoff and the open Sea. During the last decades, eutrophication has negatively influenced macrophyte communities of the coastal ecosystems, making restoration activities inevitable. This study analysed recent macrophyte vegetation and the reproductive potential through the sediment diaspore reservoir along the German Baltic Sea coastline. Salinity was identified to be the responsible factor for shifts in the macrophyte community with most commonly found species like Stuckenia pectinata or Myriophyllum spicatum. In contrast, the oospores of small charophytes (e.g. Tolypella nidifica) clearly dominated the sediment diaspore bank. The germination rates differed in the recent vegetation composition and the diaspore bank composition with Zannichellia palustris as the dominant species. However, several species not visually detected at the respective sites were represented in the diaspore bank and germinated at a low rate (e.g. Chara contraria and Lamprothamnium papulosum). The maximal germination frequency corresponded to the sediment layer in which diaspore density was the highest (5–15 cm). In conclusion, the germinable diaspores were observed at all sites. Considering the differences between the diaspore composition, recent vegetation and germination success, we have illustrated the potential of the diaspore banks for the restoration of the macrophyte communities after at least mid-term periods of disturbance." (source : auteurs) Type de publication : périodique Référence biblio : Nowak P., Steinhardt T., Von Ammon U., Rohde H., Schoor A., Holzhausen A., Schaible R., Schubert H., 2018 - Diaspore bank analysis of Baltic coastal waters. Botany letters, 165 (1) : 159-173. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67244
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 159-173[article]Exemplaires
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Titre : Morphological adaptations of Chara baltica and Chara liljebladii (Characeae) under different light conditions Type de document : Livre Auteurs : Petra Nowak, Auteur ; Hendrik Schubert, Auteur ; Anja Holzhausen, Auteur ; Veronika Sommer, Auteur ; Ralf Schaible, Auteur Année de publication : 2018 Article en page(s) : pp. 67-75 Langues : Anglais Catégories : [Thèmes] Algues
[Thèmes] Charophytes / Characées
[Thèmes] EcologieMots-clés : Phenotypic plasticity light acclimation Résumé : "Individuals within wild populations differ substantially in their fitness as a result of either genetic differences or acclimation. Within the Charophyte algae, the two taxa Chara baltica and C. liljebladii predominate at different water depths of the same habitat. The two taxa are mainly distinguished by quantitative characteristics, pointing to light acclimation. In particular, they differ by a length of the internode and the bract cells, as well as the cortication type. Genetic analyses revealed that individuals of both morphotypes are genetically identical, and hence may belong to the same species. In the present paper, we tested a hypothesis that C. liljebladii is a low-light phenotype of C. baltica. Can a C. baltica phenotype be transferred into a C. liljebladii (and vice versa) by manipulation of the environmental conditions such as irradiance? We observed significant changes in the morphology of C. baltica: decreasing the irradiance significantly increased the growth of the branchlets and internodal cells. Consequently, the plants grew larger, changing their morphology in the direction of the C. liljebladii morphotype. In the reverse experiment, subjecting C. liljebladii to increasing irradiances, the individuals had slightly better growth, but none of the analysed morphological characteristics changed significantly. Both taxa have thus shown different adaptations to light limitation. Their morphologies cannot be transferred into each other by environmental factors. Thus, the presence of the different morphologies reflects the ecological characteristics of their habitats, such as light availability or turbidity." (source : auteurs) Type de publication : périodique Référence biblio : Nowak P., Schubert H., Holzhausen A., Sommer V., Schaible R., 2018 - Morphological adaptations of Chara baltica and Chara liljebladii (Characeae) under different light conditions. Botany letters, 165 (1) : 67-75. ID PMB : 67226 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67226
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 67-75[article]Exemplaires
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Titre : Viability assessment and estimation of the germination potential of charophyte oospores : testing for site and species specificity Type de document : Livre Auteurs : Anja Holzhausen, Auteur ; Christian Porsche, Auteur ; Hendrik Schubert, Auteur Année de publication : 2018 Article en page(s) : pp. 147-158 Langues : Anglais Mots-clés : charophyte  desiccation  diaspore  dormance  irradiance  TTC test Résumé : "Anthropogenic disturbance over several decades has caused aquatic ecosystems to deteriorate, raising concerns about their condition and, consequently, prompting restorative activities. The recovery of submerged vegetation (notably charophytes) is a crucial requirement for the restoration of eutrophic aquatic systems. The success of this action often depends on the availability and germinability of aquatic plant diaspores. To characterize the potential of the diaspore bank for the restoration of charophyte stands, we investigated viability, germination potential and conditions for dormancy breaking of the oospores in three independent studies. The viability of the oospores was determined by means of the triphenyltetrazolium chloride (TTC) test. The germination potential of the diaspore banks from seven locations was estimated for potential irradiance dependency and the impact of factors influencing the dormancy status was assessed. For the latter aspect, the germination experiments were conducted with solitary oospores from plants and diaspore banks, pretreated under different temperature and desiccation regimens. The results showed species-specific differences in dormancy breakage and germination of 10 charophyte species. Five of the species tested, Chara filiformis Hertzsch, Lychnothamnus barbatus (Meyen) Leonh., Tolypella glomerata (Desvaux) Leonh., Nitella mucronata (A.Braun) Miq. in Hall and Nitella flexilis (L.) C. Agardh/Nitella opaca (C. Agardh ex Bruz.) C. Agardh, exhibited light-dependent germination. The irradiances where maximum germination was achieved correspond well to the species’ distribution within the vertical irradiance gradient in their habitats." Type de publication : périodique Référence biblio : Holzhausen A., Porsche C., Schubert H., 2018 - Viability assessment and estimation of the germination potential of charophyte oospores : testing for site and species specificity. Botany letters, 165 (1) : 147-158. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67243
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 147-158[article]Exemplaires
Cote Localisation Disponibilité P0177-6 Brest Exclu du prêt
