Epiphyte Biomass and Canopy Microclimate in the Tropical Lowland Cloud Forest of French Guiana

Authors

  • Christine Gehrig-Downie,

    1. Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
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  • André Obregón,

    1. Faculty of Geography, Laboratory for Climatology and Remote Sensing (LCRS), Deutschhausstrasse 10, University of Marburg, 35032 Marburg, Germany
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  • Jörg Bendix,

    1. Faculty of Geography, Laboratory for Climatology and Remote Sensing (LCRS), Deutschhausstrasse 10, University of Marburg, 35032 Marburg, Germany
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  • S. Robbert Gradstein

    1. Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
    2. Muséum Naturelle d'Histoire Naturelle, Dept. Systématique et Evolution, C.P. 37, 57 Rue Cuvier, 75321 Paris cedex 05, Paris, France
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ABSTRACT

Recent work on bryophyte diversity in lowland forests of northern South America has suggested the existence of a new type of cloud forest, the ‘tropical lowland cloud forest’ (LCF). LCF occurs in river valleys in hilly areas with high air humidity and morning fog, and is rich in epiphytes. We explored epiphyte abundance and canopy microclimate of LCF in a lowland area (200–400 m asl) near Saül, central French Guiana. We analyzed the vertical distribution of epiphytic cover and biomass on 48 trees, in LCF and in lowland rain forest (LRF) without fog. Trees in LCF had significantly more epiphytic biomass than in LRF; mean total epiphytic biomass in LCF was about 59 g/m2, and 35 g/m2 in LRF. In all height zones on the trees, total epiphyte cover in LCF exceeded that in LRF, with ca 70 percent mean cover in LCF and ca 15 percent in LRF. During both wet and dry seasons, mean diurnal relative air humidity (RH) was higher in LCF than in LRF, and persistence of high RH after sunrise significantly longer in LCF. We suggest that the prolonged availability of high air humidity in LCF and the additional input of liquid water through fog, enhance epiphyte growth in LCF by shortening the desiccation period and lengthening the period of photosynthetic activity of the plants.

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