trié(s) par (Pertinence décroissant(e), Titre croissant(e)) 

Identification and taxonomy of Betula (Betulaceae) in Great Britainand Ireland / Andy Amphlett in British & Irish Botany, vol. 3, n°2 (Année 2021)  

Public [article]  inBritish & Irish Botany > vol. 3, n°2 (Année 2021) . - pp. 99)135 Titre : Identification and taxonomy of Betula (Betulaceae) in Great Britainand Ireland Type de document : texte imprimé Auteurs : Andy Amphlett, Auteur Année de publication : 2021 Article en page(s) : pp. 99)135 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Betula [Espèces (in biblio)] Betula nana [Espèces (in biblio)] Betula pendula [Espèces (in biblio)] Betula pubescens [Thèmes] Morphologie végétale Mots-clés : hybridation  comparaison d'espèces  description botanique Résumé : "Floras and identification guides typically do not list the full range of identification features that discriminate between Betula pendula Rothand B. pubescens Ehrh., and some accounts contain errors. Discriminatory identification features are described and illustrated. Introgression from the diploid, B. pendula into B. pubescens is widespread. It also occurs from B. nana L. into B. pubescens, but obviously introgressed examples of the latter are probably rare. Betula pubescens presents the greatest unresolved identification difficulties. Trees identified as B. pubescens subsp. celtiberica (Rothm. & Vasc.) Rivas Mart., particularly in Wales, may be part of the variation within British B. pubescens, due to introgression from B. pendula. The most widespread of the small-leaved forms of B. pubescens is correctly named var. fragrans Ashburner & McAll. Several misapplied names have been given to this taxon, most recently subsp. tortuosa (Ledeb.) Nyman, which does not occur in Europe. Not all small-leaved B. pubescens are var. fragrans; some examples show clear signs of introgression from B. nana, and may be referable to the northern var. pumila (L.) Govaerts." (source : auteur) Type de publication : périodique Référence biblio : Amphlett A., 2021 - Identification and taxonomy of Betula (Betulaceae) in Great Britainand Ireland. British & Irish Botany, 3 (2) : 99)135. ID PMB : 71541 En ligne : https://britishandirishbotany.org/index.php/bib/article/view/84/114 Format de la ressource électronique : document Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71541 [article]

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Resource availability at three presumed stages of a heathland succession on the Lüneburger Heide, Germany / Christoph Leuschner in Journal of Vegetation Science, vol. 4, n°2 (Année 1993)

Public [article]  inJournal of Vegetation Science > vol. 4, n°2 (Année 1993) . - pp. 255-262 Titre : Resource availability at three presumed stages of a heathland succession on the Lüneburger Heide, Germany Type de document : texte imprimé Auteurs : Christoph Leuschner, Auteur Année de publication : 1993 Article en page(s) : pp. 255-262 Langues : Anglais (eng) Catégories : [habitats/milieux] 31 - Landes et fruticées [habitats/milieux] 4 - Forêts [Espèces (in biblio)] Betula pendula [Espèces (in biblio)] Fagus sylvatica [Espèces (in biblio)] Pinus sylvestris [Espèces (in biblio)] Quercus petraea [Thèmes] Relation sol - végétation Mots-clés : changement de végétation  succession secondaire  potentiel sol-eau  nutriment Résumé : "The availability of maj or plant resources was investigated in three vegetation types that were assumed to represent different stages of a secondary succession on heathland on the Lüneburger Heide, northwestern Germany. Canopy transmission and absorption of photosynthetically active radiation (PAR), soil-water availability, and nutrient (Ca, K, Mg, N, P) availability were monitored with high spatial and temporal resolution in (1) a Calluna vulgaris heathland, (2) a pioneer birch-pine forest and (3) a late-successional oak-beech forest, situated close to each other on comparable geological substrate (diluvial). Mean fractional transmission of PAR during summer decreased from 0.48 in the heathland to 0.04 in the oak-beech forest while the fractional canopy absorption increased from 0.49 to 0.92. Soil-water availability as indicated by the soil-water potential, was significantly influenced by differential canopy interception loss and characteristic rooting patterns in the three vegetation types. Annual mean nutrient concentrations in the equilibrium soil solution were similar or, for some elements, increased from the heathland to the birch-pine and the oak-beech forest despite a growing demand. A marked increase was found for the total nutrient pools in the soil-organic layer between early and late successional vegetation types. On the poor glacial parent material, nutrient pools seem to be strongly dependent on stand productivity and litter production which increased with succession. Thus, for nutrients, facilitation seems to be important in this type of succession." (source : auteur) Type de publication : périodique Référence biblio : Leuschner C., 1993 - Resource availability at three presumed stages of a heathland succession on the Lüneburger Heide, Germany. Journal of Vegetation Science, 4 (2) : 255-262. ID PMB : 70411 DOI : 10.2307/3236112 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=70411 [article]

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