Bryological and Lichenological Section/ABLS
Llaneza-Garcia, Estefania , Rosenstiel, Todd , Graves, Camille , Eppley, Sarah .
Trade-offs between growth ability and stress tolerance in a geothermal bryophyte system.
Life history theory predicts a trade-off between stress tolerance and growth, resulting in organisms that can withstand stressful habitats but are poor competitors in more mesic habitats. This predicted trade-off has been tested in few bryophytes. We examined desiccation physiology and interspecific competition in a geothermal bryophyte system where geothermal vents allow desiccation and thermal stress to be decoupled to test the productivity hypothesis. Relative humidity, rather than temperature, was more important in influencing bryophyte distributions and chlorophyll fluorescence, a measure of physiological stress, in this geothermal system, suggesting that water availability is a key factor in determining community structure. Individuals of Campylopus introflexus, a species that occurs in the most extreme sites with respect to water availability and temperature, and Aulacomniun palustre, the most common species, showed differential abilities to compensate for desiccation stress: C. introflexus plants were able to maintain chlorophyll fluorescence for 48 hours at 50% water loss, while A. palustre plants showed extreme signs of stress within 12 hours. Furthermore, under mesic conditions, C. introflexus plants had a significantly lower competitive ability than A. palustre plants, as predicted from theory. As we increased desiccation stress by increasing light levels, the relative competitive effect of C. introflexus increased while that of A. palustre decreased, lending support to the idea of a trade-off between desiccation tolerance and growth in these bryophyte species. We discuss our results with respect to plant desiccation tolerance and stress physiology.
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1 - Portland State University, Biology, 1719 SW 10th Avenue, Portland, Oregon, 97201, US
2 - Portland State University, Biology, 1719 SW 10th Avenue, Portland, Oregon, 97201
3 - Portland State University, Biology, P.O. Box 751, Portland, OR, 97207-0751, United States
4 - Portland State University, Biology Department, Po Box 751, Portland, Oregon, 97207-0751, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM