Comparison of Water Use of Various Trees Grown in Several Different Habitats

Abstract

To evaluate the water use of various trees in several different habitats, we measured leaf transpiration rate, stomatal conductance, and leaf and soil water potential to calculate leaf-specific hydraulic conductance and difference between soil and leaf water potentials. We also made P-V curve measurement to evaluate leaf water relations of these trees. Explicating leaf-specific hydraulic conductance, leaf water characteristics and transpiration rate together, we illustrated the manner of water use in several tall trees that compose their forest canopy. Although Fagus crenata Blume, a cool-temperate deciduous broad-leaved species, had higher leaf-specific hydraulic conductance, its leaf water potential at turgor loss point is higher indicating dehydration-postpone strategy. In Chamaecyparis obtusa Sieb. et Zucc., a temperate conifer, declines of leaf-specific hydraulic conductance and transpiration in dry period suggest occurrence of hydraulic disorder and stomatal regulation. Four warm-temperate evergreen species maintained low stomatal conductance even in wet period, and improved leaf dehydrate-tolerance by Osmo-regulation in dry period. Two tropical evergreen broad-leaved species have low leaf-specific hydraulic conductance, whereas Dipterocarpus sublamellatus Foxw., one emergent species, have higher leaf-specific hydraulic conductance compared to other two species, suggesting that it have a feed-water system overcome distant water transport.