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Abstract Detail


New Advances in Fern Ecology

Dubuisson, Jean-Yves [1], Hennequin, Sabine [1], Reeb, Catherine [2], Dajoz, Isabelle [3].

Diversity and structure of rainforest communities of Hymenophyllaceae on the islands of Guadeloupe and La Reunion: a comparative ecological and historical approach.

THE filmy fern family Hymenophyllaceae is widely distributed in tropical rainforests with some representatives in humid temperate areas. In tropical rainforests they often build a dominant hygrophilous epiphyte community on the lower tree trunks (with few exceptions as canopy-epiphytes). We compared the diversity and ecological preferences of this community between the lowland rainforests of two geographically distant tropical islands displaying more or less equivalent habitats: Guadeloupe (Lesser Antilles) and La Reunion (Indian Ocean). The objective of this study was to evaluate the relative contribution of local ecological parameters, as well as historical (phylogenetic) background, to observed similarities and differences between communities of Hymenophyllaceae. In the studied plots, alpha-diversity of filmy ferns is almost equivalent in each island (respectively 14 taxa in Guadeloupe and 13 in La Reunion), but with only a single species (Hymenophyllum hirsutum (L.) Sw.) in common. However, the average relative abundance of each taxon and the proportions of occupied habitats contrast strongly. In La Reunion the community is dominated by morphologically adapted colonial epiphytes with a single terrestrial taxon, while in Guadeloupe more than 50% are terrestrial taxa, or taxa with terrestrial morphology. These contrasts in abundance and ecological preferences seem to be partially due to the strong local differences in the forest physiognomy (especially the nature and proportion of potential supports for epiphytes) combined with differences in host-specificity in epiphytes. Furthermore, the important influence of the historical biogeographic background (provided by phylogeny) on geographically distant communities is discussed (e.g., terrestrial Guadeloupean species originated from a mostly terrestrial neotropical clade, while the Asiatic and African-Madagascan clades that have provided La Reunion taxa mostly include epiphytic species). Ecosystem and community structures therefore appear significantly history-constrained. [c.e.:srb]


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1 - Lab. Paleobotanique, UMR 5143, Universite Pierre et Marie Curie, 12 rue Cuvier, Paris, F-75005, France
2 - Lab. Informatique et Systematique, UMR 5143, Universite Pierre et Marie Curie, 12 rue Cuvier, Paris, F-75005, France
3 - Labo Ecologie, ENS, 46 rue Ulm, Paris, F-75230, France

Keywords:
Hymenophyllaceae
epiphytism
tropical island
rainforest
community
biogeography
Guadeloupe
La Reunion.

Presentation Type: Symposium or Colloquium Presentation
Session: 1-4
Location: 114/MODOC
Date: Monday, July 31st, 2006
Time: 9:15 AM
Abstract ID:487


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