Acclimation of trees and ecosystems to higher temperature and altered water sources

人类活动正在改变大气中二氧化碳的浓度，造成气温升高、降水和积雪融化模式改变等后果。我建议启动一系列新的实验室和实地研究，以调查北方针叶树的驯化和适应以及整个生态系统对变化的环境条件的反应。在阿尔伯塔省南部落基山脉东坡的草原和森林生态系统之间的尖锐过渡地带，樟子松(Pinus Conorta)和道格拉斯冷杉(Pseudotsuga Menziesii)占据主导地位。这是用于树木和生态系统生理学研究的理想区域和物种集合，因为这一过渡带应该非常容易受到预期的气候变化的影响，包括气温变暖和水源可获得性的变化(冰雪融化模式的改变，春季/夏季降水的变化)。我计划的研究将调查光合作用、呼吸作用、蒸腾作用和水分利用效率对温度升高的反应，以及控制观察到的反应的生理机制。我们将研究树干水分运输效率与树木对高温引起的光合作用和生长下降的敏感性之间的联系。将使用稳定的同位素示踪剂来测量树木对积雪融化水和春季/夏季降水的吸收和利用的变化。我们的测量将与生理模型的预测进行比较，以进一步了解机械控制和物种之间对环境变化反应的潜在敏感性差异的原因。最后，我们的测量将被用来初始化和测试当前条件下的详细的生态系统模型，以便该模型可以用于预测未来气候变化情景下的树木和生态系统的生理响应。

Human activities are altering the concentration of atmospheric carbon dioxide with consequences such as warmer air temperatures and altered precipitation and snow melt patterns. I propose to initiate a series of new lab and field studies to investigate the acclimation and adaptation of northern conifer trees and whole ecosystem response to altered environmental conditions. Lodgepole pine (Pinus contorta) and Douglas-fir (Pseudotsuga menziesii) trees dominate the eastern slopes of the Rocky Mountains in southern Alberta at the sharp transition zone between grassland and forest ecosystems. This is an ideal area and set of species to use in studies of tree and ecosystem physiology because this transition zone should be very susceptible to anticipated climate changes, including warmer temperatures and shifts in the availability of water sources (altered snow melt patterns, change in spring/summer precipitation). My planned studies will investigate the response of photosynthesis, respiration, transpiration and water-use efficiency to increases in temperature and the physiological mechanisms controlling the observed responses. We will study the linkages between the efficiency of water transport through tree stems and tree sensitivity to high temperature-induced declines in photosynthesis and growth. Stable isotope tracers will be used to measure variation in the uptake and use of snow melt water and spring/summer precipitation by trees. Our measurements will be compared to predictions of physiological models to gain further understanding of the mechanistic controls and the reasons for potential differences in sensitivity between species in their response to environmental changes. Finally, our measurements will be used to initialize and test a detailed ecosystem model under current conditions, so that the model can be used to predict tree and ecosystem physiological responses under proposed scenarios of future climate change.