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Abstract Detail

Comparative Algal and Byrophyte Physiology

Rice, Steven K. [1], Hanson, David T. [2], Aclander, Lynn [1].

Relationships among tissue-, canopy- and photosynthetic characteristics in Sphagnum mosses, a comparative study.

Photosynthetic characteristics vary greatly among species in the bryophyte genus Sphagnum. To understand how differences in plant tissue- and canopy-level traits contribute to that variation, we undertook a broad comparative study. Five species pairs from different taxonomic sections were collected and grown in a common greenhouse environment. Species pairs included S. magellanicum and S. portoricense, S. fallax and S. recurvum, S. contortum and S. lescurii, S. squarrosum and S. teres, and S. girgensohnii and S. tenerum. Light saturated rates of net photosynthesis (Amax), quantum yield, and light compensation points were estimated from photosynthetic light response curves (n=3). Other physiological characteristics included δ13C and the chlorophyll fluorescence parameters quantum efficiency of PSII at maximum (Fv/Fm) and 300 PPFD (Fv/Fm) and non-photochemical quenchng. These parameters were compared with each other and with tissue- and plant-traits that should influence the ability of a canopy to utilize light energy and included biomass, pigment concentrations (chlorophylls a+b, carotenoids), C/N and their vertical distribution. In addition, water content, tissue density, surface roughness, canopy height and canopy light transmittance were measured. Plant tissue- and canopy-level characteristics were highly correlated. Species with low water contents and reduced pigment and N concentrations, but with biomass and pigments distributed proportionally in the upper canopy, allowed deep canopy light transmission and possessed high Amax. Overall, the concentration of carotenoids was the strongest predictor of Amax expressed on a biomass, chlorophyll or N basis (R2>0.64, inverse relationship), likely reflecting their role in preventing photoinhibition. The δ 13C values were inversely related to Amax expressed using chlorophyll or N and Fv/Fm and Fv/Fm measures were highly correlated with Amax on a surface area basis. These trait associations define a diversification profile whereby tissue- and canopy-level traits evolve synchronously in combinations that relate clearly to physiological function.

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1 - Union College, Department of Biology, Schenectady, New York, 12308, USA
2 - University of New Mexico, Department of Biology, 167 Castetter Hall, Albuquerque, New Mexico, 87131, USA

stable isotope
functional morphology

Presentation Type: Symposium or Colloquium Presentation
Session: SY13
Location: Stevens 4/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:15 AM
Number: SY13006
Abstract ID:1477

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