Dynamics of leaf water relations components in co‐occurring iso‐ and anisohydric conifer species |
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Authors: | FREDERICK C MEINZER DAVID R WOODRUFF DANIELLE E MARIAS KATHERINE A MCCULLOH SANNA SEVANTO |
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Institution: | 1. USDA Forest Service, Pacific Northwest Research Station, , Corvallis, OR, 97331 USA;2. Department of Forest Ecosystems and Society, Oregon State University, , Corvallis, OR, 97331 USA;3. Department of Botany, University of Wisconsin, , Madison, WI, 53706 USA;4. Earth and Environmental Sciences Division, Los Alamos National Laboratory, , Los Alamos, NM, 87545 USA |
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Abstract: | Because iso‐ and anisohydric species differ in stomatal regulation of the rate and magnitude of fluctuations in shoot water potential, they may be expected to show differences in the plasticity of their shoot water relations components, but explicit comparisons of this nature have rarely been made. We subjected excised shoots of co‐occurring anisohydric Juniperus monosperma and isohydric Pinus edulis to pressure‐volume analysis with and without prior artificial rehydration. In J. monosperma, the shoot water potential at turgor loss (ΨTLP) ranged from ?3.4 MPa in artificially rehydrated shoots to ?6.6 MPa in shoots with an initial Ψ of ?5.5 MPa, whereas in P. edulis mean ΨTLP remained at ~ ?3.0 MPa over a range of initial Ψ from ?0.1 to ?2.3 MPa. The shoot osmotic potential at full turgor and the bulk modulus of elasticity also declined sharply with shoot Ψ in J. monosperma, but not in P. edulis. The contrasting behaviour of J. monosperma and P. edulis reflects differences in their capacity for homeostatic regulation of turgor that may be representative of aniso‐ and isohydric species in general, and may also be associated with the greater capacity of J. monosperma to withstand severe drought. |
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Keywords: | anisohydry drought isohydry osmotic potential turgor |
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