Watkins, James , Testo, Weston , Martin, L. , Oliver, Melvin J. .
Ecophysiology of tropical epiphytic filmy ferns (Hymenophyllaceae) across a range of habitats and ecosystems.
The filmy ferns are an ecophysiological conundrum. Unlike other fern sporophytes, filmy ferns lack stomata and produce leaves that are mostly one-cell thick.This combination of characters would naturally lead one to expect filmy ferns to be limited to shaded, wet habitats. Yet, from tropical lowland forests to open paramo habitats, species can be found growing terrestrially, as trunk epiphytes along creeks and swamps, understory epiphytes in upland plains, and as epiphytes on bright, dry, emergent canopy trees. The goal of this study was to examine several ecophysiological characteristics from species across a range of habitats in lowland and montane forests and paramo habitats. In total we examined 11 epiphytic species across these ecosystems to include high canopy epiphytes and understory epiphytes from open and closed forests. We generated photosynthetic light response curves using gas exchange techniques for all taxa and examined species' ability to recover from desiccation and light stress using chlorophyll fluorescence as an index of recovery. As expected, taxa from exposed habitats demonstrated higher maximum area based photosynthetic rates and higher respiratory demand than those from more climatically moderated habitats. Most taxa exhibited some degree of desiccation tolerance, yet species from high canopy and Paramo habitats were more tolerant. Surprisingly, species across habitats were markedly sensitive to light stress, and desiccation combined with light stress killed most taxa. Filmy ferns have radiated into a diversity of habitats and have evolved a wide range of desiccation tolerance. Our data suggest that light may be more critical in shaping species distributions than water.
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1 - Colgate University, Department Of Botany, 129 Ho Science Center, 13 Oak Drive, Hamilton, NY, 13346-1338, USA
2 - Colgate University, Box Z 5647, Hamilton, NY, 13346, USA
3 - University of Missouri, Columbia, Plant Sciences, 205 Curtis Hall, Columbia, MO, 65211, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union E/Hyatt
Date: Monday, July 9th, 2012
Time: 8:45 AM