Aspinwall Michael J, Vårhammar Angelica, Blackman Chris J, Tjoelker Mark G, Ahrens Collin, Byrne Margaret, Tissue David T, Rymer Paul D
Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
Science Division, Department of Parks and Wildlife, Locked Bag 104, Bentley Delivery Centre, Western Australia 6983, Australia.
Tree Physiol. 2017 Aug 1;37(8):1095-1112. doi: 10.1093/treephys/tpx047.
Short-term acclimation and long-term adaptation represent two ways in which forest trees can respond to changes in temperature. Yet, the relative contribution of thermal acclimation and adaptation to tree physiological responses to temperature remains poorly understood. Here, we grew two cool-origin and two warm-origin populations of a widespread broad-leaved evergreen tree species (Corymbia calophylla (Lindl.) K.D.Hill & L.A.S.Johnson) from a Mediterranean climate in southwestern Australia under two growth temperatures representative of the cool- and warm-edge of the species distribution. The populations selected from each thermal environment represented both high and low precipitation sites. We measured the short-term temperature response of leaf photosynthesis (A) and dark respiration (R), and attributed observed variation to acclimation, adaptation or the combination of both. We observed limited variation in the temperature optimum (Topt) of A between temperature treatments or among populations, suggesting little plasticity or genetic differentiation in the Topt of A. Yet, other aspects of the temperature response of A and R were dependent upon population and growth temperature. Under cooler growth temperatures, the population from the coolest, wettest environment had the lowest A (at 25 °C) among all four populations, but exhibited the highest A (at 25 °C) under warmer growth temperatures. Populations varied in R (at 20 °C) and the temperature sensitivity of R (i.e., Q10 or activation energy) under cool, but not warm growth temperatures. However, populations showed similar yet lower R (at 20 °C) and no differences in the temperature sensitivity of R under warmer growth temperatures. We conclude that C. calophylla populations from contrasting climates vary in physiological acclimation to temperature, which might influence how this ecologically important tree species and the forests of southwestern Australia respond to climate change.
短期驯化和长期适应是森林树木应对温度变化的两种方式。然而，热驯化和适应对树木温度生理响应的相对贡献仍知之甚少。在这里，我们在代表该物种分布冷边缘和暖边缘的两种生长温度下，种植了来自澳大利亚西南部地中海气候的一种广泛分布的阔叶常绿树（红胶桉（Corymbia calophylla (Lindl.) K.D.Hill & L.A.S.Johnson））的两个冷源种群和两个热源种群。从每个热环境中选择的种群代表了高降水量和低降水量地点。我们测量了叶片光合作用（A）和暗呼吸（R）的短期温度响应，并将观察到的变化归因于驯化、适应或两者的结合。我们观察到，温度处理之间或种群之间，A的最适温度（Topt）变化有限，这表明A的Topt可塑性或遗传分化很小。然而，A和R的温度响应的其他方面取决于种群和生长温度。在较冷的生长温度下，来自最冷、最湿润环境的种群在所有四个种群中A（25°C时）最低，但在较温暖的生长温度下A（25°C时）最高。在凉爽但不是温暖的生长温度下，种群在R（20°C时）和R的温度敏感性（即Q10或活化能）方面存在差异。然而，在较温暖的生长温度下，种群显示出相似但较低的R（20°C时），并且R的温度敏感性没有差异。我们得出结论，来自不同气候的红胶桉种群在温度生理驯化方面存在差异，这可能会影响这种具有生态重要性的树种以及澳大利亚西南部森林对气候变化的响应。
