Response of high-latitude forests to a warmer and CO2-enriched atmosphere: tree rings in a process-based model

近年来，北极和北美亚北极地区的气温一直在上升，预计将继续上升。此外，全球大气中的二氧化碳正在增加。该项目将评估白云杉对这些持续变化的反应。它将使用来自10个地点的存档样本，标准的树木年轮方法，辅以新的化学分析，以及数值模型来了解树木生长对不断变化的环境驱动因素的反应。阿拉斯加的木材工业近年来一直在衰退。该项目的成功成果将为森林管理者和规划人员提供有用的信息。人力资源的发展将得到促进，因为这将是美国国家科学基金会第一次奖励给首席研究员。它还将为培养一名研究生提供支持。最后，让本科生参与到研究活动中来。教育外展将通过向来自一所学校的高中学生提供讲习班来完成，该学校为在科学和工程领域代表性不足的人口提供服务。该项目将促进利用树木年轮数据了解森林生长对自然和人为强迫的反应。在传统的树木年轮宽度和最大晚期木材密度记录的基础上，主要研究人员将建立一个高纬度稳定碳（del13C）和氧（del18O）同位素测量网络，相对于传统的树木气候测量，这将为这些变化提供一个独立的约束。该项目代表了一个跨学科的机会，将三个不同的学科结合起来：(1)基本的树木年代学技术，它允许精确的日期，定量和可验证的长期树木年轮记录；(2)利用低温地球化学工具测量能独立反映温度、降水、相对湿度和天然林水分利用效率长期生理信息等环境变量的del13C和del18O比值；(3)联合使用基于过程的机制模式MAIDENiso，以区分温度升高和大气CO2升高的混合效应，并预测不同情景下的北方森林响应，并联合使用NASA GISS ModelE2一般环流模式为MAIDENiso提供输入。

Temperatures in Arctic and subarctic North America have been rising in recent years and are projected to continue to rise. Furthermore, atmospheric carbon dioxide is increasing around the globe. This project will evaluate the response of white spruce to these ongoing changes. It will use archived samples from ten sites, standard tree-ring methodologies supplemented by novel chemical analyses, and numerical models to understand tree growth response to changing environmental drivers. The Alaskan timber industry has been in decline in recent years. Successful outcomes from this project will provide useful information to forest managers and planners. Workforce development will be promoted as this would be the first NSF award to the principal investigator. It will also provide support for the training of a post-graduate scholar. Finally, it will involve undergraduate students in the research activities. Educational outreach will be accomplished through workshops to be offered to high school students from a school serving a population that is under-represented in science and engineering fields.The project will advance the use of tree-ring data in understanding forest growth responses to natural and anthropogenic forcings. Extending traditional tree-ring width and maximum latewood density records, the principal investigators will establish a high latitude network of stable carbon (del13C) and oxygen (del18O) isotope measurements, which provide an independent constraint on such changes relative to traditional dendroclimatological measurements. This project represents an interdisciplinary opportunity to combine three distinct disciplines: (1) basic dendrochronological techniques, which allow for precisely-dated, quantitative and verifiable long-term tree-ring records; (2) low temperature geochemical tools to measure del13C and del18O ratios that will independently reflect environmental variables including temperature, precipitation, relative humidity and long-term physiological information on water use efficiency in natural forests; and (3) the joint use of a process-based mechanistic model, MAIDENiso, to distinguish between the confounding effects of increases in temperatures and atmospheric CO2 and to predict boreal forest response under different scenarios, and the NASA GISS ModelE2 general circulation model to provide inputs to MAIDENiso.