Blackman Chris J, Gleason Sean M, Chang Yvonne, Cook Alicia M, Laws Claire, Westoby Mark
Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia University of Western Sydney, Hawkesbury Institute for the Environment, Richmond, NSW 2753, Australia
Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia.
Ann Bot. 2014 Sep;114(3):435-40. doi: 10.1093/aob/mcu131. Epub 2014 Jul 8.
Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested.
Leaf hydraulic vulnerability to drought (P50leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50leaf between sites were also examined.
Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50leaf values recorded within each site was positively correlated with increasing aridity. P50leaf was also a good indicator of the climatic envelope across each species' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites.
The findings indicate that species sorting processes have influenced distributional patterns of P50leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates.
叶片水力途径对水分胁迫诱导功能障碍的脆弱性是植物耐旱性的关键组成部分，在界定物种气候范围方面可能很重要。然而，跨物种和地点的叶片水力脆弱性与气候之间关联的普遍性仍有待检验。
在来自广泛生境的92种木本植物（大多为常绿被子植物）组成的多样化群体中，测量了叶片对干旱的水力脆弱性（P50leaf，即导致水力功能丧失50%的水势）。将这些新数据与一些先前发表的数据，针对与水分可利用性相关的关键气候指标进行了检验。还研究了不同地点间P50leaf位点内变异性的差异。
随着各地点年降雨量的减少和干旱程度的增加，叶片对干旱的水力脆弱性值大幅下降（即变得更负）。每个地点记录的P50leaf值的标准差与干旱程度增加呈正相关。P50leaf也是每个物种分布范围内气候包络以及它们在澳大利亚境内干旱端分布界限的良好指标，尽管这种关系在各地点内并非始终可检测到。
研究结果表明，物种分选过程影响了P50leaf在降雨谱上的分布模式，但各地点内存在应对水分亏缺的替代策略。与干旱的紧密联系表明，叶片水力脆弱性可能会影响未来气候条件下的植物分布。
