Water Resource Partitioning, Stem Xylem Hydraulic Properties, and Plant Water Use Strategies in a Seasonally dry Riparian Tropical Rainforest

• Published in: Oecologia 2003-11, Vol.137 (3), p.321-329
• Main Authors: Drake, P. L., Franks, P. J.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Carbon isotopes; Carbon Isotopes - analysis; Dry season; Dry seasons; Ecophysiology; Fundamental and applied biological sciences. Psychology; Groundwater; Hydraulic conductivity; Hydraulic properties; Hydraulics; Leaves; Plant species; Plants; Plants and fungi; Rainforests; Rainy season; Rainy seasons; Resource partitioning; Seasonal variations; Seasons; Soil water; Stable isotopes; Streams; Transpiration; Trees - physiology; Tropical Climate; Water; Water potential; Water resources; Water use; Water-Electrolyte Balance; Xylem
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-003-1352-y

This study investigated seasonal variation in the origin of water used by plants in a riparian tropical rainforest community and explored linkages between plant water source, plant xylem hydraulic conductivity and response to the onset of dry conditions. The study focused on five co-dominant canopy species, comprising three tree species (Doryphora aromatica, Argyrodendron trifoliolatum, Castanospora alphandii) and two climbing palms (Calamus australis and Calamus caryotoides). Stable isotope ratios of oxygen in water (δ18O) from soil, groundwater, stream water and plant xylem measured in the wet season and the subsequent dry season revealed water resource partitioning between species in the dry season. Measurement of stem-area-specific hydraulic conductivity ($K_{\text{S}}$) in the wet season and subsequent dry season showed a significant dry-season loss of$K_{\text{S}}$in three of the five species (Castanospora alphandii, Calamus australis and C. caryotoides) and a decrease in mean$K_{\text{S}}$for all species. This loss of hydraulic conductivity was positively correlated with the difference between wet-season and dry-season midday leaf water potentials and with leaf carbon isotope discrimination, indicating that plants that were less susceptible to loss of conductivity had greater control over transpiration rate and were more water-use efficient.