Binks Oliver, Meir Patrick, Rowland Lucy, da Costa Antonio Carlos Lola, Vasconcelos Steel Silva, de Oliveira Alex Antonio Ribeiro, Ferreira Leandro, Christoffersen Bradley, Nardini Andrea, Mencuccini Maurizio
School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FE, UK.
Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
New Phytol. 2016 Jul;211(2):477-88. doi: 10.1111/nph.13927. Epub 2016 Mar 22.
The tropics are predicted to become warmer and drier, and understanding the sensitivity of tree species to drought is important for characterizing the risk to forests of climate change. This study makes use of a long-term drought experiment in the Amazon rainforest to evaluate the role of leaf-level water relations, leaf anatomy and their plasticity in response to drought in six tree genera. The variables (osmotic potential at full turgor, turgor loss point, capacitance, elastic modulus, relative water content and saturated water content) were compared between seasons and between plots (control and through-fall exclusion) enabling a comparison between short- and long-term plasticity in traits. Leaf anatomical traits were correlated with water relation parameters to determine whether water relations differed among tissues. The key findings were: osmotic adjustment occurred in response to the long-term drought treatment; species resistant to drought stress showed less osmotic adjustment than drought-sensitive species; and water relation traits were correlated with tissue properties, especially the thickness of the abaxial epidermis and the spongy mesophyll. These findings demonstrate that cell-level water relation traits can acclimate to long-term water stress, and highlight the limitations of extrapolating the results of short-term studies to temporal scales associated with climate change.
预计热带地区将变得更温暖、更干燥，了解树种对干旱的敏感性对于描述气候变化对森林的风险至关重要。本研究利用亚马逊雨林的一项长期干旱实验，评估六个树种属中叶片水平的水分关系、叶片解剖结构及其对干旱响应的可塑性的作用。比较了季节之间和地块之间（对照和穿透降雨排除）的变量（完全膨压下的渗透势、膨压丧失点、电容、弹性模量、相对含水量和饱和含水量），从而能够比较性状的短期和长期可塑性。将叶片解剖性状与水分关系参数相关联，以确定不同组织间的水分关系是否存在差异。主要发现如下：长期干旱处理会引发渗透调节；抗旱胁迫的物种比干旱敏感物种表现出更小的渗透调节；水分关系性状与组织特性相关，尤其是叶背表皮和海绵叶肉的厚度。这些发现表明，细胞水平的水分关系性状能够适应长期水分胁迫，并突出了将短期研究结果外推到与气候变化相关的时间尺度上的局限性。
