PostDoctoral Research Fellowship

全球变化模型预测，由于气候变暖，高纬度的北方森林将越来越容易受到火灾的威胁。由于北方森林含有很大比例的陆地碳(C)储量，任何火灾制度的变化都可能对碳的交换和储存产生重大影响。本项目将采用时间序列方法来研究西伯利亚东北地区靠近北极林木线的落叶松森林中，火灾和永久冻土如何相互作用，影响森林再生和碳封存。假设火灾后土壤有机层深度作为热调节剂和种子萌发屏障，通过间接影响森林更新来调节C的储存。这项研究将以2010年夏季开始的调查为基础，并将与最近在阿拉斯加内陆进行的研究进行比较。跨极比较将增加我们对改变的火灾制度下碳动态如何在具有不同永久冻土动态和植被类型的北方地区变化的理解。该奖学金将资助博士后。通过提供北极寒带森林生态学方面的培训、执行独立研究的经验、指导本科生的技能，以及与美国国内外北极研究人员合作的机会，来解决有关改变的火灾制度如何间接影响西伯利亚落叶松森林碳循环的基本问题。这项研究将为一个生态重要但研究不足的地区提供急需的信息，并将提高我们预测气候变化和改变的火灾制度对北极生态系统影响的能力。西伯利亚落叶松林占所有北方森林生态系统的20%，是全球C循环的重要组成部分。它们与其他北方森林的不同之处在于，它们由单一树种（落叶松属）组成，具有落叶生长习性，通常生长在连续的永久冻土层上。因此，它们对气候变暖和火灾变化的反应可能不同于其他地区的北方森林。由于在西伯利亚进行研究的后勤限制，以及俄语科学成果的英文翻译很少，我们目前对它们的生态学和对气候变化的潜在易感性的了解仍然有限。目前西伯利亚寒带森林中碳库的不确定性仍然是影响我们预测气候引起的全球碳循环变化能力的一个重要因素。通过将结果与阿拉斯加内陆研究相对充分的北方森林进行比较，这项研究将进一步提高我们的能力，以检测在不同的永久冻土特征和植被类型的地区，北方对变化的火灾的反应是否相似，或者是否需要更详细的研究来准确模拟生态系统对气候变化的反应。这项研究将有助于我们了解北方森林火灾如何影响全球碳循环，并为扩大北方森林碳库规模、估计北方森林火灾的碳排放以及校准未来全球碳循环的预测模型提供必要的数据。更广泛的影响：这项研究将促进我们对西伯利亚落叶松森林的了解，这是一个重要的生态系统，但研究不足，同时提高博士后研究人员的教学和指导技能。博士后？通过参与美国国家科学基金会资助的北极星项目系列讲座和讨论小组，以及在生态系统生态学领域的本科生助理的指导下，将美国国家科学基金会的研究活动、方法和发现融入到本科生的教育中。在俄罗斯远东地区的东北科学站进行实地研究，将为博士后、美国其他北极研究人员和俄罗斯合作者之间建立伙伴关系提供一个场所。这些合作将用于将研究成果与俄罗斯的科学努力相结合。拟议研究的科学发现将通过在科学期刊上的出版物、在国际会议上的演讲，以及更非正式地通过博士后研究员的帖子，广泛传播。S网页。活动层和土壤湿度测量结果将提交给环极活动层监测网络，为气候变化对北方森林生态系统影响的模式验证和扩大提供关键数据。

Global change models predict high-latitude boreal forests will become increasingly susceptible to fire threat due to climate warming. Because boreal forests contain a large proportion of terrestrial carbon (C) stocks, any change to the fire regime will likely have substantial impacts on C exchange and storage. This project will utilize a chronosequence approach to examine how fire and permafrost interact to influence forest regeneration and C sequestration within larch forests near arctic treeline in Far Northeastern Siberia. The hypothesis is that post-fire soil organic layer depth mediates C storage through indirect impacts on forest regeneration because of its role as a thermal regulator and barrier to seed germination. This research will build on investigations initiated in summer 2010 and will be compared to recent and ongoing research within Interior Alaska. A cross-polar comparison will increase our understanding of how C dynamics under an altered fire regime vary across boreal regions with differing permafrost dynamics and vegetation types. This fellowship will support the post-doctoral fellow?s career goals by providing training in arctic boreal forest ecology, experience in executing independent research, skills in mentoring undergraduate students, and an opportunity to collaborate with arctic researchers from within and outside the U.S. By addressing fundamental questions concerning how an altered fire regime indirectly impacts C cycling of Siberian larch forests, this study will provide much needed information about an ecologically important yet understudied region and will improve our ability to predict the impacts of climate change and altered fire regimes on arctic ecosystems.Siberian larch forests comprise 20% of all boreal forest ecosystems and are a critical component of the global C cycle. They are different from other boreal forests in that they are comprised of a single tree genus (Larix spp.), with a deciduous growth habit, that often grows on continuous permafrost. Thus, their response to warming climate and an altered fire regime is likely to differ from boreal forests in other regions. Our current knowledge of their ecology and potential susceptibility to climate change remains limited because of logistical constraints associated with conducting research in Siberia and minimal translations of Russian scientific efforts into English. Uncertainties regarding current C pools in Siberian boreal forests remain a significant factor affecting our ability to predict climate-induced changes to the global C cycle. By comparing results to the relatively well-studied boreal forests of interior Alaska, the study will further our ability to detect whether boreal response to changing fire is similar across zones differing in permafrost characteristics and vegetation types, or whether more detailed studies are needed for accurate modeling of ecosystem response to climate change. The study will contribute to our understanding of how boreal fires impact global C cycling and provide essential data necessary for scaling-up boreal forest C pools, estimating C emissions from boreal fires, and calibrating predictive models of future global C cycling.Broader Impacts: The research will advance our understanding of Siberian larch forests, an important yet understudied ecosystem, while advancing the teaching and mentoring skills of a post- doctoral researcher. The post-doctoral fellow?s research activities, methodologies, and findings will be integrated into the education of undergraduate students through participation in the NSF-funded Polaris Project lecture series and discussion groups and by mentoring of an undergraduate field assistant in ecosystem ecology. Basing field research out of the Northeast Science Station in the Russian Far Northeast will provide a venue for building partnerships between the post-doctoral fellow, other arctic researchers from the U.S., and Russian collaborators. The collaborations will be used to integrate research findings with Russian scientific efforts. Scientific findings resulting from the proposed research will be widely disseminated through publications in scientific journals, presentations at international conferences, and more informally, through postings on the post-doctoral researcher?s web page. Active layer and soil moisture measurements will be submitted to the Circumpolar Active Layer Monitoring network to provide critical data for model validations and scaling-up of climate change impacts on boreal forest ecosystems.