Bourne Aimee E, Creek Danielle, Peters Jennifer M R, Ellsworth David S, Choat Brendan
Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia.
Ann Bot. 2017 Jul 1;120(1):123-133. doi: 10.1093/aob/mcx020.
Plant hydraulic traits influence the capacity of species to grow and survive in water-limited environments, but their comparative study at a common site has been limited. The primary aim of this study was to determine whether selective pressures on species originating in drought-prone environments constrain hydraulic traits among related species grown under common conditions.
Leaf tissue water relations, xylem anatomy, stomatal behaviour and vulnerability to drought-induced embolism were measured on six Eucalyptus species growing in a common garden to determine whether these traits were related to current species climate range and to understand linkages between the traits.
Hydraulically weighted xylem vessel diameter, leaf turgor loss point, the water potential at stomatal closure and vulnerability to drought-induced embolism were significantly ( P < 0·05) correlated with climate parameters from the species range. There was a co-ordination between stem and leaf parameters with the water potential at turgor loss, 12 % loss of conductivity and the point of stomatal closure significantly correlated.
The correlation of hydraulic, stomatal and anatomical traits with climate variables from the species' original ranges suggests that these traits are genetically constrained. The conservative nature of xylem traits in Eucalyptus trees has important implications for the limits of species responses to changing environmental conditions and thus for species survival and distribution into the future, and yields new information for physiological models.
植物水力性状影响物种在水分受限环境中的生长和存活能力，但在同一地点对其进行的比较研究一直有限。本研究的主要目的是确定源自干旱易发环境的物种所面临的选择压力是否会限制在共同条件下生长的相关物种间的水力性状。
对种植在同一园圃中的六种桉属树种的叶片组织水分关系、木质部解剖结构、气孔行为以及对干旱诱导栓塞的脆弱性进行了测量，以确定这些性状是否与当前物种的气候范围相关，并了解各性状之间的联系。
水力加权木质部导管直径、叶片膨压丧失点、气孔关闭时的水势以及对干旱诱导栓塞的脆弱性与物种分布范围内的气候参数显著相关（P < 0·05）。茎和叶的参数之间存在协同关系，膨压丧失时的水势、12%的导水率损失以及气孔关闭点显著相关。
水力、气孔和解剖性状与物种原始分布范围内的气候变量之间的相关性表明，这些性状受到遗传限制。桉树木质部性状的保守性质对于物种应对不断变化的环境条件的限度具有重要意义，进而对物种未来的生存和分布产生重要影响，并为生理模型提供了新的信息。
