Water Conservation in Artemisia tridentata through Redistribution of Precipitation

• Published in: Oecologia 2004-10, Vol.141 (2), p.335-345
• Main Authors: Ryel, R. J., Leffler, A. J., Peek, M. S., Ivans, C. Y., Caldwell, M. M.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Arid environments; Artemisia - physiology; Artemisia tridentata; Biological and medical sciences; Computer Simulation; Drought; Foliage; Fundamental and applied biological sciences. Psychology; General aspects; Hydraulics; Models, Theoretical; Moisture content; Plant roots; Plant Roots - physiology; Plant Transpiration - physiology; Plants; Precipitation; Pulse Events and Arid Ecosystems; Rain; Semiarid environments; Soil; Soil columns; Soil conductivity; Soil depth; Soil hydraulic properties; Soil water; Soil water content; Soil water recharge; Summer; Transpiration; Utah; Water - physiology; Water availability; Water conservation; Water potential; Water shortages; Water storage; Water use
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-003-1421-2

Water conservation is important for plants that maintain physiologically active foliage during prolonged periods of drought. A variety of mechanisms for water conservation exist including stomatal regulation, foliage loss, above- and below-ground allocation patterns, size of xylem vessels and leaf pubescence. Using the results of a field and simulation study with Artemisia tridentata in the Great Basin, USA, we propose an additional mechanism of water conservation that can be used by plants in arid and semi-arid environments following pulses of water availability. Precipitation redistributed more uniformly in the soil column by roots (hydraulic redistribution of water downward) slows the rate at which this water can subsequently be taken up by plants, thus prolonging water availability during periods of drought. By spreading out water more uniformly in the soil column at lower water potentials following precipitation events, water use is reduced due to lower soil conductivity. The greater remaining soil water and more uniform distribution result in higher plant predawn water potentials and transpiration rates later in the drought period. Simulation results indicate that plants can benefit during drought periods from water storage following both summer rain events (small summer pulses) and overwinter recharge (large spring pulse). This mechanism of water conservation may aid in sustaining active foliage, maintaining root-soil hydraulic connectivity, and increasing survival probability of plants which remain physiologically active during periods of drought.