Responses of boreal trees to rising atmospheric carbon dioxide concentration

自工业革命以来，大气二氧化碳浓度([CO2])一直在迅速增加，而且在可预见的未来还将继续增加。不断上升的[二氧化碳]将影响植物和生态系统的生理、生长和分布。北方森林是地球上最大的陆地生态系统，它对[二氧化碳]上升的反应将影响全球气候条件以及依赖北方森林的事物，例如野生动物和森工。这项研究将考察北方树木在实验室和田间条件下对上升的[二氧化碳]的反应。这些结果将加深我们对北方树木对[CO2]上升的响应的理解，并将其用于计算机模型，以预测未来气候条件下北方森林的生长、结构和分布的变化。在二氧化碳海拔研究中，常用的技术有三种：围栏(生长室和温室)、开顶室和自由空气二氧化碳浓缩(FACE)。每种方法都有其优缺点，例如，封闭结构很好地控制了所有的环境条件，并且操作成本低廉。由于它的运作不受季节的限制，它对生长季节较短的地区特别有吸引力，例如加拿大。然而，它不允许对大树或树木群落进行调查。相比之下，Face允许进行更大规模的实地实验，但建立和操作起来极其昂贵。脸谱内的[CO2]有很大的时空变化，它向大气中排放了大量的CO2，而且不可能控制所有其他环境因素。使用不同方法的植物反应通常遵循相似的趋势，但幅度不同。我们将研究潜在的反应差异的机制，并在围栏和脸部实验之间建立树木反应的定量关系。这些结果将帮助研究人员设计更好的围栏研究，并使过去的围栏研究结果更有用。数量关系对于开发和/或参数化用来预测[CO2]上升对北方森林的影响的生态系统模型至关重要。

The atmospheric carbon dioxide concentration ([CO2]) has been increasing rapidly since the Industrial Revolution and the increase will continue in the foreseeable future. The rising [CO2] will affect the physiology, growth and distribution of plants and ecosystems.  The boreal forest is the largest terrestrial ecosystem on the earth and its response to rising [CO2] will influence the global climate conditions as well as things that depend on the boreal forest, e.g., wildlife and the forest industry. This research will examine how boreal trees respond to rising [CO2] under both lab and field conditions. The results will enhance our understanding of how boreal trees will respond to rising [CO2] and be used in computer models to predict changes in the growth, structure and distribution of the boreal forest under future climate conditions.There are three common techniques used in CO2 elevation research: enclosures (growth chambers & greenhouses), open top chambers and Free Air CO2 Enrichment (FACE). Each method has its merits and drawbacks, e.g., enclosures control all environmental conditions well and are inexpensive to operate. Because its operation is not limited by the season, it is especially attractive to regions with short growing seasons, e.g., Canada. However, it doesn't permit the investigation on large trees or tree communites. In contrast, FACE permits larger scale field experiments, but is extremely expensive to establish and operate. There are large spatial and temporal variations in [CO2] within a FACE plot, it discharges large amount of CO2 into the atmosphere and it is impossible to control all other environmental factors. The plant responses using different methods generally follow similar trends but differ in magnitude. we will examine mechanisms underlying the response differences and establish quantitative relationships in tree response between enclosure and FACE experiments. The results will help researchers design better enclosure studies and make the results of past enclosure studies more useful. The quantitative relationships will be critical for the development and/or parameterization of ecosystem models for predicting the impact of rising [CO2] on the boreal forest.