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3 résultat(s) recherche sur le mot-clé 'cycle de vie' 
trié(s) par (Pertinence décroissant(e), Titre croissant(e)) Affiner la recherche Générer le flux rss de la rechercheThe life cycle of a parthenogenetic population of Chara canescens from an interdunal Mediterranean pond / Sara Calero in Botany letters, vol. 165, n°1 (Année 2018)
Titre : The life cycle of a parthenogenetic population of Chara canescens from an interdunal Mediterranean pond Type de document : Livre Auteurs : Sara Calero, Auteur ; Maria Rodrigo, Auteur Année de publication : 2018 Article en page(s) : pp. 55-65 Langues : Anglais Mots-clés : charophyte phénologie reproduction cycle de vie oogonia maturation oospore size brackish pond Résumé : "Chara canescens lives in shallow brackish waters in the northern hemisphere. It has been described as an annual species that mostly reproduces by parthenogenesis, being the only species of Chara able to do so. However, much is still unknown about its life cycle and the differences between the sexual and the parthenogenetic populations. We monitored the life cycle of a parthenogenetic population growing in a brackish interdunal pond in the Albufera de València Natural Park (Spain). Approximately 30 specimens were harvested every 15–30 days throughout 2015. The longest polar axis and the largest equatorial diameter were measured, and the isopolarity index was calculated for the oogonia and the oospores. The non-swollen and the swollen oogonia were distinguished by size. This population had a short life cycle, but two types of shoots with different life history traits were found. A few small individuals overwintered underneath the emergent vegetation. In early March, new shoots appeared from the germinating oospores, growing fast and colonizing more open waters. The first oogonia appeared in April, enlarging and ripening along the first five whorls of the shoots. The oospores were produced in less than 15 days after the first oogonia emergence. The ripe oospores were small (average size ± SD: 392 ± 34 × 219 ± 24 ?m; isopolarity index: 181 ± 22). Parthenogenetic reproduction lasted 5 months. No new fructifications were produced from September onwards. Although the oospores were smaller than those described in the literature for the species, they were clearly viable and enabled the persistence of the population through the winter." Type de publication : périodique Référence biblio : Calero S., Rodrigo M., 2018 - The life cycle of a parthenogenetic population of Chara canescens from an interdunal Mediterranean pond. Botany letters, 165 (1) : 55-65. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67224
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 55-65[article]Exemplaires
Cote Localisation Disponibilité P0177-6 Brest Exclu du prêt Ecology and management of Juncus effusus (soft rush) on cutaway peatlands / Mark McCorry (2003)
Titre : Ecology and management of Juncus effusus (soft rush) on cutaway peatlands Type de document : Livre Auteurs : Mark McCorry, Auteur ; Florence Renou, Auteur Editeur : Dublin [Irlande] : University College Dublin. Department of Environmental Resource Management Année de publication : 2003 Collection : Forest Ecosystem Research Group Report num. 69 Importance : 66 p. Note générale : BOGFOR Research Programme Langues : Français Catégories : [ZG] Irlande
[habitats/milieux] 5 - Tourbières et marais
[habitats/milieux] ZH - Zones humides
[Espèces (in biblio)] Juncus effususMots-clés : sol agricole sylviculture méthode de contrôle cycle de vie biologie écologie Résumé : "Many of the original conifer tree crops planted on cutaway peatlands in the Irish midlands in the 1980s have failed to produce a commercial crop. Competing vegetation has been identified as one of the main factors influencing at some point their successful establishment. Juncus effusus is one of the most frequent and abundant plant species found growing on cutaway peatland sites. This species has created severe management problems at certain sites because of its competition with young trees and attempts to control it have been made with mixed success.
J. effusus is particularly well adapted to colonising and spreading over bare cutaway peatlands. This species prefers a wet acidic environment with slightly enriched nutrient conditions and seasonal water level fluctuations, but has a broad ecological range. It is therefore able to form the dominant part of vegetation on large areas of cutaway peatlands. There is no relatively unique set of environmental characteristics that distinguishes J. effususdominated areas from other similar areas. J. effusus is relatively easy to control in agricultural situations but is much more difficult to control in cutaway peatland forestry situations. The life-cycle of J. effusus has few weaknesses that can be easily exploited to increase control efficiency in a forest situation.
The current management of J. effusus-dominated vegetation uses hand-cleaning, mowing and weed-wiping methods. In some cases this has altered the vegetation type but in others, there is re-growth of J. effusus. It was concluded that more intensive control methods are required to control J. effusus effectively. It is not known if the current management practices are actually able to positively influence the establishment and growth of the planted conifers. It was concluded that more research is required to investigate more thoroughly (1) the population biology and ecology of J. effusus on cutaway peatlands and (2) different control treatments of J. effusus on bare cutaway peatlands, and the influence of these treatments on the growth and establishment of planted conifers." (source : auteurs)Type de publication : rapport d'études Référence biblio : McCorry M., Renou F., 2003 - Ecology and management of Juncus effusus (soft rush) on cutaway peatlands. Dublin : University College Dublin. Department of Environmental Resource Management, 66 p. (Forest Ecosystem Research Group Report ; 69). ID PMB : 69085 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=69085 Exemplaires
Cote Localisation Disponibilité aucun exemplaire
Titre : New insights into the ecology and phenology of two Characeae : N. opaca (Bruzelius) C. Agardh and N. gracilis (Sm.) C. Agardh Type de document : Livre Auteurs : Dominique Auderset Joye, Auteur ; Aurélie Boissezon, Auteur Année de publication : 2018 Article en page(s) : pp. 91-102 Langues : Anglais Catégories : [ZG] Suisse
[habitats/milieux] ZH - Zones humidesMots-clés : cycle de vie growing degree days pond bed air exposure water chemistry light Résumé : "The study addressed the ecology and life cycle of two charophyte species, which are both at risk of extinction and on several Red Lists in Europe. Populations of Nitella opaca and N. gracilis, sometimes occurring together in three wetland ponds, were monitored for several years, and environmental data were also recorded. The pattern and timing of emergence (new shoots) and maturation of the sexual organs (antheridia, oogonia, and ripe oospores) were determined on plant samples collected regularly. The species phenophases were related to the environmental data. The results showed that species distribution can be linked to the water calcium content, a parameter that most differed in the three ponds. N. gracilis developed population only in ponds with very low calcium concentrations, whereas N. opaca had a wider tolerance. Following a pond bed air exposure in previous year, dense populations of N. opaca and N. gracilis were observed. None, or only a few individuals, were found when the waterbodies remained flooded the whole preceding year. Light and temperature affect differently the emergence of sex organs and the maturation of oospores. Both species differed in the timing of their phenophases. N. opaca appeared in March, reproduced and disappeared in July. N. gracilis was generally observed later in spring, and after full reproduction, the plants started a second cycle in late summer, while new oospore germination occurred. N. gracilis was perennial and reproduced all year long. Taking these results into account will help to design conservation plans for N. opaca and N. gracilis." (source : auteurs) Type de publication : périodique Référence biblio : Auderset Joye D., Boissezon A., 2018 - New insights into the ecology and phenology of two Characeae : N. opaca (Bruzelius) C. Agardh and N. gracilis (Sm.) C. Agardh. Botany letters, 165 (1) : 91-102. ID PMB : 67239 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67239
in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 91-102[article]Exemplaires
Cote Localisation Disponibilité P0177-6 Brest Exclu du prêt
