Abstract
This study examined how leaf and stem functional traits related to gas exchange and water balance scale with two potential proxies for tree hydraulic architecture: the leaf area:sapwood area ratio (A
L:A
S) and wood density (ρ
W). We studied the upper crowns of individuals of 15 tropical forest tree species at two sties in Panama with contrasting moisture regimes and forest types. Transpiration and maximum photosynthetic electron transport rate (ETR
max) per unit leaf area declined sharply with increasing A
L:A
S as did the ratio of ETR
max to leaf N content, an index of photosynthetic nitrogen-use efficiency. Midday leaf water potential, bulk leaf osmotic potential at zero turgor, branch xylem specific conductivity, leaf-specific conductivity, and stem and leaf capacitance all declined with increasing ρ
W. At the branch scale, A
L:A
S and total leaf N content per unit sapwood area increased with ρ
W resulting in a 30-percent increase in ETR
max per unit sapwood area with a doubling of ρ
W.
Keywords
Capacitance,
functional convergence,
hydraulic architecture,
osmotic potential,
photsynthesis,
transpiration,
water potential
Citation
Meinzer, Frederick C.; Campanello, Paula I.; Domec, Jean-Christophe; Gatti, M. Genoveva; Goldstein, Guillermo; Villalobos-Vega, Randol; Woodruff, David R. 2008. Constraints on physiological function associated with branch architecture and wood density in tropical forest trees. Tree Physiology. 28: 1609-1617