title: Hydraulic Balance of aEucalyptus urophyllaPlantation in Response to Periodic Drought in Low Subtropical China.
abstract: A clear understanding of hydraulic regulation in cultivated plants is crucial for addressing challenges to forest water cycling due to climate changes in low subtropical China. Experiments were conducted to determine the hydrologic balance of aEucalyptus urophyllaplantation in response to periodic drought. Trees displayed lower stomatal conductance (GS) and leaf water potentials (ΨL) during the dry periods. A decrease of 22.4% was found for the maximum reference GS(GSatD= 1 kPa; GSref-max). Accordingly, specific hydraulic conductivity (ks) decreased by 45.3 - 65.6% from the wet to the dry season, depending on the tree size. Fairly stable leaf stomatal conductance (gs) with decreasing ΨL(ΨL< -1.6 MPa) contributed to the high water-use efficiency (WUE) of thisEucalyptusspecies. Additionally, the lower stomatal sensitivity (-m= 0.53) in the dry season might also be responsible for the high WUE, since we found an anisohydric behavior that was associated with photosynthetically active radiation (Q0). Larger trees were found to use water more efficiently than small trees, due to the higher sensitivity of ksto decreasing ΨL. This was also verified by the decreasing leaf carbon isotope discrimination (Δ13C) with increasing tree diameter. However, further studies are needed to determine the universality of these results for other Eucalyptus species in this region.
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China; College of Life Sciences, University of Chinese Academy of SciencesBeijing, China.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China; Guangdong Provincial Key Laboratory of Applied Botany, South China Institute of Botany (CAS)Guangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman OK, USA.
authors.forename: Heather R
authors.initials: HR
authors.lastname: McCarthy
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS) Guangzhou, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ouyang
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS) Guangzhou, China.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Niu
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS) Guangzhou, China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS) Guangzhou, China.
authors.forename: Guangyan
authors.initials: G
authors.lastname: Ni
authors.affiliation: Guangxi Institute of Botany (CAS) Guilin, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Huang
keywords: Eucalyptus urophylla; anisohydric; hydraulic balance; stomatal conductance; water use efficiency