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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #319631
Title: Whole-plant capacitance, embolism resistance and slow transpiration rates all contribute to longer desiccation times in woody angiosperms from arid and wet habitats

Author
item Gleason, Sean
item BLACKMAN, CHRIS - Macquarie University
item COOK, ALICIA - Macquarie University
item LAWS, CLAIRE - Macquarie University
item WESTOBY, MARK - Macquarie University

Submitted to: Tree Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2013
Publication Date: 2/1/2014
Citation: Gleason, S.M., Blackman, C.J., Cook, A.M., Laws, C.A., Westoby, M. 2014. Whole-plant capacitance, embolism resistance and slow transpiration rates all contribute to longer desiccation times in woody angiosperms from arid and wet habitats. Tree Physiology. 34(3):275-84.

Interpretive Summary: High levels of drought stress can damage the water transporting tissues in plants (xylem), yet little is understood about which plant traits (e.g., water storage, evaporation rates from leaves, etc.) have most influence in delaying the onset of dysfunction during periods of drought. We examined three traits contributing to longer desiccation times in excised shoots of 11 species from two sites of contrasting aridity: (i) the amount of water released from plant tissues (storage tissues inside the plant); (ii) the minimum level of water stress preceding damage; and (iii) the rate of evaporation from leaves. The time required for species to reach acute levels of stress varied markedly, ranging from 1.3 h to nearly 3 days. Water released from storage tissues, minimum stress preceding damage, and evaporation rates all contributed significantly to longer desiccation times, explaining 28, 22 and 50% of the variation in the time required to reach acute stress. Interestingly, these three traits were nearly independent to one another, suggesting that they do not represent alternative strategies, but likely trade off with other traits not measured in this study. The majority of water lost during desiccation (60–91%) originated from leaves, suggesting that leaves are an important source of water during desiccation.

Technical Abstract: Low water potentials in xylem can result in damaging levels of cavitation, yet little is understood about which hydraulic traits have most influence in delaying the onset of hydraulic dysfunction during periods of drought. We examined three traits contributing to longer desiccation times in excised shoots of 11 species from two sites of contrasting aridity: (i) the amount of water released from plant tissues per decrease in xylem water potential (W'); (ii) the minimum xylem water potential preceding acute water stress (defined as P50L; water potential at 50% loss of leaf conductance); and (iii) the integrated transpiration rate between the points of full hydration and P50L (Wtime). The time required for species to reach P50L varied markedly, ranging from 1.3 h to nearly 3 days. W', P50L and Wtime all contributed significantly to longer desiccation times, explaining 28, 22 and 50% of the variance in the time required to reach P50L. Interestingly, these three traits were nearly orthogonal to one another, suggesting that they do not represent alternative hydraulic strategies, but likely trade off with other ecological strategies not evaluated in this study. The majority of water lost during desiccation (60–91%) originated from leaves, suggesting an important role for leaf capacitance in small plants when xylem water potentials decrease below -2 MPa.