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4 résultat(s) recherche sur le mot-clé 'colonisation' 
trié(s) par (Pertinence décroissant(e), Titre croissant(e)) Affiner la recherche Générer le flux rss de la rechercheLe chêne sessile (Quercus petraea Liebl.) et le chêne pédonculé (Q. robur L.) : deux espèces différentes ? / Stéphane Herbette in Digitalis, n°10 (Année 2014)
Titre : Le chêne sessile (Quercus petraea Liebl.) et le chêne pédonculé (Q. robur L.) : deux espèces différentes ? Type de document : Livre Auteurs : Stéphane Herbette, Auteur Année de publication : 2014 Article en page(s) : pp. 34-41 Langues : Français Catégories : [habitats/milieux] 4 - Forêts
[Espèces (in biblio)] Quercus petraea Liebl.
[Espèces (in biblio)] Quercus robur L.
[ZG] Europe
[Thèmes] Chêne sessile (Chêne noir, Chêne rouvre)Mots-clés : systématique carte de répartition évolution dispersion colonisation morphologie écologie hybridation Résumé : "Le chêne pédonculé (Quercus robur) et le chêne sessile (Q. petraea) sont des arbres abondants dans les forêts tempérées d'Europe. En plus de cohabiter dans de nombreux habitats, ces deux espèces sont inter-fertiles et leurs hybrides sont donc très fréquents. Les échanges génétiques sont si courants que les différences morphologiques et moléculaires entre les 2 espèces ne sont pas nettes. Malgré ces hybridations, les 2 espèces se sont maintenues, et la question sur leur statut d'espèce est posée. Ces hybridations pourraient même expliquer leur succès dans la colonisation post-glaciaire de la végétation." (source : auteur) Type de publication : périodique Référence biblio : Herbette S., 2014 - Le chêne sessile (Quercus petraea Liebl.) et le chêne pédonculé (Q. robur L.) : deux espèces différentes ? Digitalis, 10 : 34-41. ID PMB : 59933 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=59933
in Digitalis > n°10 (Année 2014) . - pp. 34-41[article]Exemplaires
Cote Localisation Disponibilité P0229 Brest Exclu du prêt The ecological significance of sexual reproduction in peat mosses (Sphagnum) / Sebastian Sundberg (2000)
Titre : The ecological significance of sexual reproduction in peat mosses (Sphagnum) Type de document : Livre Auteurs : Sebastian Sundberg, Auteur Editeur : Acta Universitatis Upsaliensis Année de publication : 2000 Collection : Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology num. 581 Importance : 37 p. ISBN/ISSN/EAN : 91-554-4847-X Langues : Anglais Mots-clés : colonisation perturbation expérience longévité spore bryophyte Résumé : "Peat mosses (Sphagnum) are widely distributed and are a major component of mire vegetationand peat throughout the boreal and temperate regions. Most boreal Sphagnum species regu-larly produce sporophytes, but the ecological role of the spore has been questioned. This studyshows that the spores can form a spore bank and have the ability to germinate and contributeto moss establishment whenever suitable conditions occur. The results suggest that spore pro-duction is important for explaining the wide distribution and omnipresence of Sphagnum innutrient-poor wetlands. The results further imply that initial recruitment from spores predomi-nates in Sphagnum after disturbance or formation of suitable habitats.A series of experiments showed that addition of phosphorus-containing substrates, suchas fresh plant litter or moose dung, resulted in spore establishment on bare, moist peat. A fieldexperiment indicated establishment rates of about 1% of sown, germinable spores on peatwith added substrates. Plant litter on moist soil, without a closed cover of bryophytes, is animportant safe site for the establishment of Sphagnum spores. The results fit the observed pat-tern of colonisation by Sphagnum beneath Eriophorum vaginatum tussocks in mires severelydisturbed by peat extraction. Successful long-distance dispersal was indicated by the occur-rence of several regionally new or rare Sphagnum species in disturbed mires.Spore number per sporophyte ranged among Sphagnum species from 18 500 to 240 000,with a trade-off between spore number and spore size. Annual spore production was estimatedat 15 million spores per square metre on two investigated mires. Sporophyte productionshowed a large interannual variation. Sporophyte production was positively related to theamount of precipitation the preceding summer. This was probably because a high water levelpromoted gametangium formation. Spore dispersal occurred in July and August. The earliertiming of spore dispersal in the more drought-sensitive, hollow-inhabiting sphagna should re-duce the risk of sporophytes drying out prematurely during summer droughts.Spores kept refrigerated up to 13 years retained high germinability. A field experimentshowed that Sphagnum can form a persistent spore bank, with a potential longevity of severaldecades." (source : auteur) Type de publication : livre Référence biblio : Sundberg S., [s. d.] - The ecological significance of sexual reproduction in peat mosses (Sphagnum). Acta Universitatis Upsaliensis, 37 p. (Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology ; 581). En ligne : http://www.diva-portal.org/smash/get/diva2:166017/FULLTEXT01.pdf Format de la ressource électronique : document Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=66027 Exemplaires
Cote Localisation Disponibilité aucun exemplaire
Titre : Clonal architecture and internal isoenzymatic variability of the bryophyte Polytrichum commune hedw. during post‐fire regeneration Type de document : Livre Auteurs : Pierre Corradini, Auteur ; M.-A. Esnault, Auteur ; Bernard Clément, Auteur Année de publication : 1999 Article en page(s) : pp. 145-155 Langues : Anglais Catégories : [ZG] BRETAGNE (53)
[habitats/milieux] 3 - Landes, fruticées et prairies
[Thèmes] BryophytesMots-clés : après incendie croissance clonale colonisation Résumé : "In the heathlands of Brittany, Polytrichum commune is a pioneer moss that becomes established after fires. Two approaches were used to follow clonal growth in a sample of 20 colonies. Four cohort stem ages were identified (1 to 4 years old). Stem density profiles for different stem cohorts across colonies showed a predominantly central cohort 1 stem density maximum (32% of all stems). Colonies expanded by adding new cohorts both over and beyond the area already occupied. A pair of distant stems was analysed for 7 isozyme systems. Twenty‐three banding patterns were determined. No one colony was variable for all systems. For the 20 colonies tested, 27 distinct phenotypes were identified. Banding patterns were similar for the paired stems analysed in 10 of the 20 colonies which expressed 7 of the 27 phenotypes. The 10 other colonies shared 20 phenotypes. Five colonies were selected for a detailed study. No colony was perfectly homogeneous. Four colonies were quite uniform and expressed a single phenotype. The fifth colony was variable for 5 of the 7 systems and could express more than one phenotype. Colony structure, with a high central stem density, probably reflects a clonal architecture. Only one colony had an internal genetic heterogeneity, indicating the possible coexistence of two genotypes in a single colony. The results do not allow any assessment of the correspondence between the physical and genetic structure of colonies." (source : auteurs) Type de publication : périodique Référence biblio : Corradini P., Esnault M.-A., Clément B., 1999 - Clonal architecture and internal isoenzymatic variability of the bryophyte Polytrichum commune hedw. during post‐fire regeneration. Plant Biosystems, 133 (2) : 145-155. ID PMB : 71301 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71301
in Plant Biosystems > vol. 133, n°2 (Année 1999) . - pp. 145-155[article]Exemplaires
Cote Localisation Disponibilité TAP CORR Brest Exclu du prêt
Titre : Growth pattern and modular reiteration of a hardy coloniser Polytrichum commune Hedw. Type de document : Livre Auteurs : Pierre Corradini, Auteur ; Bernard Clément, Auteur Année de publication : 1999 Article en page(s) : pp. 67-76 Langues : Anglais Catégories : [ZG] FINISTERE (29)
[habitats/milieux] 3 - Landes, fruticées et prairiesMots-clés : colonisation après incendie population biologique Résumé : "Heathlands in Brittany are subject to recurrent summer burning. Recolonisation after large fires begins with bryophytes, but species composition during succession may be altered by colonies of Polytrichum commune Hedw. which appears to be able to prevent reestablishment of the typical heathland formation. Three complementary levels of investigation were adopted in attempting to understand how P. commune, manages to persist and succeed in space open to rapid saturation.
Analysis at the level of the local plant community, showed radical changes in the distribution and composition of the herbaceous and muscinal layers over two years. Between May 1992 and May 1994, P. commune cover increased from 13% to 77% accompanied by an appreciable decrease in other pioneer species.
We compared individual colony growth of P. commune with that of Polytrichum piliferum, another pioneer moss. In both species, horizontal and vertical growth occurred in spring and autumn. During 1995, P. commune colony diameter had increased by a factor of 4.0 compared with 3.6 for P. piliferum. Over the same interval, colony height increased by a factor of 1.3 for P. commune compared with 1.8 for P. piliferum.
Analysis at the level of the module showed that 79% of experimentally cultured stems produced branches, 25% producing a single branch, 32% two branches, and 25% 4 to 7 branches. The lower the location of new branches on culture stems, the longer their leafed section and the greater their overall length. These new branches were morphologically and functionally new ramets.
These observations on P. commune conform to the inhibition model of community succession (Connell & Slatyer 1977). Successional patterns recorded in the present study could be interpreted in terms of differences in species colony growth ability. Dense colony growth would allow a species to saturate one of the more important ecosystem compartment. Polytric capacity to grow simultaneously and efficiently in the few centimetres in and above the soil surface could prevent seedling establishment and decrease fitness of coexisting Poaceae." (source : auteurs)Type de publication : périodique Référence biblio : Corradini P., Clément B., 1999 - Growth pattern and modular reiteration of a hardy coloniser Polytrichum commune Hedw. Plant ecology, 143 (1) : 67-76. ID PMB : 71300 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=71300
in Plant ecology > vol. 143, n°1 (Année 1999) . - pp. 67-76[article]Exemplaires
Cote Localisation Disponibilité TAP CORR Brest Exclu du prêt
