Community and Ecosystem Dynamics of a Northern Temperate Forest Exposed to Elevated CO2 and O3 in a FACE System

9652675 Karnosky温室气体，二氧化碳（CO2）和臭氧（O3），在全球范围内正在增加，并与人口增长密切相关。人们对这两种气体将如何影响森林群落知之甚少，因为到目前为止，对这两种气体的研究都是在暴露室创造的人工环境中进行的。在这个项目中，我们使用了最先进的自由空气二氧化碳富集（FACE）设备，以促进再生的森林林分长期暴露于升高的二氧化碳和臭氧中，无论是单独的还是联合的。该设施正在威斯康星州莱茵兰德附近的美国林务局土地上建造。一个由多学科科学家组成的团队将研究颤杨（Populus tremuloides）、糖枫（Acer saccharum）和纸桦树（Betula papyrifera）在各种竞争组合中的机制和反应。特别感兴趣的是：(1)树木的生理、生长、生存和生产力；(2)基因型和物种间的竞争相互作用；(3)乔木和林分碳氮分配；(4)叶面防御化合物调控的病虫害和胁迫耐受性；(5)碳氮循环与生态系统碳储量。在随机完全区组设计中，为处理的因子组合（对照、CO2、O3、CO2、+ O3）建立了三个重复FACE环。我们的研究策略将包括并行实验和建模。因此，来自这些处理组合的响应数据将用于参数化和改进现有的全树和林分水平过程模型。我们的实验设计将允许我们使用对比生活史的物种来解决特定的假设，同时也为模型参数化提供最大可能的推断范围。

9652675 Karnosky The greenhouse gases, carbon dioxide (CO2) and ozone (O3), are increasing globally and are closely tracking population growth. Little is known about how these two gases will impact forest communities, as, until now, studies with these gases were done in artificial environments created by exposure chambers. In this, project we are using a state-of-the-art Free-Air Carbon Dioxide Enrichment (FACE) facility to facilitate long-term exposures of regenerating forest stands to elevated CO2 and O3, alone and in combination. The facility is being constructed on United States Forest Service land near Rhinelander, Wisconsin. A multidisciplinary team of scientists will examine mechanisms and responses in trembling aspen (Populus tremuloides), sugar maple (Acer saccharum) and paper birch (Betula papyrifera) in various competitive combinations. Of particular interest are: (1) tree physiology, growth, survival, and productivity; (2) competitive interactions among genotypes and species; (3) tree and stand carbon and nitrogen allocation; (4) pest and stress tolerance as regulated by foliar defense compounds; and (5) carbon and nitrogen cycling and ecosystem carbon storage. Three replicate FACE rings are being established for a factorial combination of treatments (control, CO2, O3, CO2, + O3) in a randomized complete block design. Our research strategy will include parallel experimentation and modeling. Thus, response data from these treatment combinations will be used to parameterize and refine an existing whole-tree and stand level process model. Our experimental design will allow us to address specific hypotheses using species of contrasting life-histories, while also affording the largest possible scope of inference for model parameterization.