Manioc : Portail | resultats 121 - 140 pour la recherche: Dispersion factor

Histoire de la Martinique depuis la colonisation jusqu'en 1815. Tome 5
Auteur(s) : Daney de Marcillac, Sidney (1810-1893)
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Histoire philosophique et politique des établissemens et du commerce des Européens dans les deux Indes. Tome cinquième
Auteur(s) : Raynal, Guillaume-Thomas (1713-1796)
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La Guyane française : notes et souvenirs d'un voyage exécuté en 1862-1863
Auteur(s) : Bouyer, Frédéric (1822-1882) Rapine Delahaye
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Au Brésil. Aperçu général : Rio de Janeiro, finances, industries, chemins de fer, marine marchande, etc.
Auteur(s) : Walle, Paul (1872-19..)
Auteurs secondaires : Levasseur, Emile (1828-1911)
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Antigua and the Antiguans: a full account of the colony and its inhabitants from the time of the Caribs to the present day, interspersed with anecdotes and legends : also, an impartial view of slavery and the free labour systems, the statistics of the island, and biographical notices of the principal families, Volume 2
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La France moderne et le problème colonial.[1], Les traditions et les idées nouvelles, la réorganisation administrative, la reprise de l'expansion : 1815-1830
Auteur(s) : Schefer, Christian (1866-1944)
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Histoire philosophique et politique des établissemens et du commerce des Européens dans les deux Indes. Tome premier
Auteur(s) : Raynal, Guillaume-Thomas (1713-1796)
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L'affaire Légitimus et la race noire : un crime politico-judiciaire
Auteur(s) : Boussenot, Georges
Auteurs secondaires : Bérenger, Henry Victor (1867-1952)
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Diversity of plant assemblages in isolated depressional wetlands from Central-Western Europe
Auteur(s) : Herault, Bruno Thoen, Daniel
Auteurs secondaires : Ecologie des forêts de Guyane (ECOFOG) ; Ecole Nationale du Génie Rural, des Eaux et des Forêts (ENGREF) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - Centre National de la Recherche Scientifique (CNRS) Department of Environmental Sciences & Management ; Université de Liège

Éditeur(s) : HAL CCSD
Résumé :
A closed depression is defined as a geomorphologic element where a sediment depository is encircled by hillslopes. Despite the fact that closed depressions are often the only stagnant water points in many European landscapes, few ecological researches on their plant assemblages have been done. The main goal of this study was to give first results of the environmental factors responsible for the vegetation composition, richness and rarity in the closed depressions of the Lorraine biogeographical district (Belgium, France and grand-duche de Luxembourg). We surveyed for plant presence 85 forest and 77 grassland closed depressions. For each site, wetland area, local environmental factors and regional connectivities registered. For each species, the Ellenberg values were compiled. To investigate the main source of variation in species composition and in species richness (including richness in rare species), Non-metric Multidimensional Scaling analyses and Generalized Linear Models were respectively used. Species pools in forest (forest and preforest species) and in grassland (bog plants, pioneers, helophytes) were quite different. In both landscapes, a gradient from plants typical of basic high-productive soils to plants typical of acid low-productive soils reflects a shared successional gradient. The accumulation of organic matter allowed the establishment of Sphagnum spp., which slowly acidified the soil and thus acted as ecosystem engineers for the arrival of bog plants. Moreover, the species composition was additionally driven by the plant light tolerance in forests and by the plant water requirements in grasslands. Mechanisms of species accumulation (increase in species richness) were different in forests and in grasslands: respectively related to the plant light tolerance and to the wetland area. At the regional level, the averaged soil productivity was negatively related to the richness in rare species. Indeed, perennial highly-competitive plants such as Glyceria spp., Iris pseudacorus or Urtica dioica impeded the establishment of smaller and rarer species. At the habitat level, isolated closed depressions (due to either low connectivity or low grazing pressure) have more habitat rare species, giving evidences of dispersal limitation in plant assemblages of closed depressions.
7th INTECOL International Wetland Conference
Utrecht, Netherlands

hal-01032381
https://hal.archives-ouvertes.fr/hal-01032381

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