期刊
TREE PHYSIOLOGY
卷 31, 期 10, 页码 1052-1066出版社
OXFORD UNIV PRESS
DOI: 10.1093/treephys/tpr085
关键词
Corymbia calophylla; drought resistance; ecological restoration; Eucalyptus marginata; osmotic adjustment; photosynthesis; stomatal conductance; water relations
类别
资金
- Australian Research Council [LPO211478]
- University of Western Australia
- Alcoa World Alumina Australia
- Australian Postgraduate Award in Industry
This study describes the physiological response of two co-occurring tree species (Eucalyptus marginata and Corymbia -calophylla) to seasonal drought at low- and high-quality restored bauxite mine sites in south-western Australia. Seasonal changes in photosynthesis (A), stomatal conductance (g(s)), leaf water potential (Sigma), leaf osmotic potential (Sigma), leaf relative water content (RWC) and pressure-volume analysis were captured over an 18-month field study to (i) determine the nature and severity of physiological stress in relation to site quality and (ii) identify any physiological differences between the two species. Root system restriction at the low-quality site reduced maximum rates of gas exchange (g(s) and A) and increased water stress -(midday Sigma and daily RWC) in both species during drought. Both species showed high stomatal sensitivity -during drought; however, E. marginata demonstrated a higher dehydration tolerance where Sigma and RWC fell to -3.2 MPa and 73% compared with -2.4 MPa and 80% for C. calophylla. Corymbia calophylla showed lower g(s) and higher Sigma and RWC during drought, indicating higher drought tolerance. Pressure-volume curves showed that cell-wall elasticity of E. marginata leaves increased in response to drought, while C. calophylla leaves showed lower osmotic potential at zero turgor in summer than in winter, indicating osmotic adjustment. Both species are clearly able to tolerate seasonal drought at hostile sites; however, by C. -calophylla closing stomata earlier in the drought cycle, maintaining a higher water status during drought and having the additional mechanism of osmotic adjustment, it may have a greater capacity to survive extended periods of drought.
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