PARENT SESSION
Posters P3B Photosynthetic acclimation: Ecophysiology, diverse environments. Abstracts (479-522)

Photosynthesis, hydraulic conductance and canopy development: effects of P-nutrition in Rhizophora mangle. John Cheeseman^*,1, Catherine Lovelock², Marilyn Ball³, ¹ Department of Plant Biology, Urbana, IL, USA² Smithsonian Environmental Research Center, Edgewater, MD, USA³ Ecosystem Dynamics, Canberra, ACT, Australia

ABSTRACT- Photosynthesis, in the oligotrophic environment of tropical mangrove forests, is co-limited by Rubisco activity and stomatal conductance. The stomatal effect reflects, in part, the ability of the hydraulic system of the trees to supply water to the leaves. Thus, hydraulic architecture itself imposes restrictions on potential photosynthesis. In the dwarf trees which make up the interior forests on the Belizean mangrove cays, P-fertilization dramatically increases growth, including stem elongation and leaf production; both photosynthetic capacity and stomatal conductance increase concomitantly. In addition to increasing the carbon supply to the tree as a whole, this also increases the flux of water through individual branches and the trunk. In this paper, we detail the changes in water demand associated with increased leaf area and stomatal conductance, and the associated increase in diameters of xylem vessels and stem hydraulic conductivity.

KEY WORDS: hydraulic architecture, phosphorous nutrition, mangrove, leaf area index