Document: FRE-3-19-1

Ecophysiology of plant water use: Convergence from leaf to tree.

MEINZER, F.C.* ¹ and G.GOLDSTEIN ²

USDA Forest Service, Corvallis, OR 97331 USA ¹
University of Hawaii, Honolulu, HI 96822 USA ²

Abstract:
Traditionally, comparative ecophysiological investigations of plant water utilization have focused on stomatal regulation of transpiration at the leaf level. The patterns of behavior observed are often tacitly assumed to reflect species-specific differences in stomatal responsiveness. However, results of recent studies point to considerable functional convergence in regulation of transpiration and other processes among taxonomically diverse species, and to the need for scaling across different levels of organization. We have studied regulation of water use over a range of scale from leaf to whole plant simultaneously in tropical trees growing in Panama, Brazil and Hawaii. This approach has revealed that simple scaling variables related to tree size, hydraulic architecture as reflected in the leaf area:sapwood area ratio, boundary layer conditions as influenced by leaf size and crown architecture, and sapwood properties such as density and saturated water content, appear to govern operating ranges along common physiological response curves. Conclusions about species-specific behavior drawn solely from a set of leaf-level observations may therefore be misleading in the absence of knowledge of whole-plant architectural and structural features contributing to the behavior of individual leaves. The ability to identify appropriate scaling factors that reveal areas of functional convergence will simplify interpretation and modeling of tree, stand, and ecosystem level processes in forests.

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This abstract is being presented at: 10:45 AM in session:
Symposium # 9: The Water Limitation: Issues in Plant, Community, and Ecosystem Water Use.