PostDoctoral Research Fellowship

博士后研究奖学金

• 批准号: 1103443
• 负责人: Heather Alexander
• 金额: $ 16.13万
• 依托单位: Alexander Heather D
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-15 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1103443&HistoricalAwards=false
• 关键词: PostDoctoral; Research; Fellowship

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.

全球变化模型预测，由于气候变暖，高纬度北方森林将变得越来越容易受到火灾威胁。由于北方森林含有很大比例的陆地碳（C）储量，任何改变火灾制度将可能对C交换和存储产生重大影响。该项目将利用时序方法来研究火灾和冻土如何相互作用，以影响森林再生和碳封存在西伯利亚东北部的北极树线附近的落叶松林。这一假设是，火后土壤有机层深度介导的C存储通过间接影响森林更新，因为它的作用是作为一个热调节器和种子萌发的障碍。这项研究将建立在2010年夏季开始的调查基础上，并将与阿拉斯加内陆最近和正在进行的研究进行比较。一个跨极的比较将增加我们的理解如何C动态下改变火制度不同的北方地区不同的永冻土动态和植被类型。这个奖学金将支持博士后研究员？通过提供北极北方森林生态学的培训，执行独立研究的经验，指导本科生的技能，以及与美国内外的北极研究人员合作的机会，通过解决有关如何改变火灾制度间接影响西伯利亚落叶松森林C循环的基本问题，这项研究将为一个生态上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火灾状况改变对北极生态系统影响的能力。西伯利亚落叶松林占北极生态系统的20%，是所有北方森林生态系统的重要组成部分，是全球碳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，它们由单一的树属（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上。因此，它们对气候变暖和火灾状况改变的反应可能不同于其他地区的北方森林。我们目前对它们的生态和对气候变化的潜在敏感性的了解仍然有限，因为在西伯利亚进行研究的后勤限制以及俄罗斯科学成果翻译成英语的数量很少。目前西伯利亚北方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相对研究充分的北方森林进行比较，该研究将进一步提高我们的能力，以检测北方对火灾变化的反应是否在永久冻土特征和植被类型不同的区域之间相似，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理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、估算北方森林火灾的碳排放量以及校准未来全球碳循环的预测模型提供必要的数据。这项研究将促进我们对西伯利亚落叶松林的了解，这是一个重要但尚未得到充分研究的生态系统，同时提高博士后研究人员的教学和指导技能。博士后研究员？的研究活动，方法和研究结果将通过参与NSF资助的北极星项目系列讲座和讨论小组，并通过指导本科生在生态系统生态学领域的助理，融入到本科生的教育中。在俄罗斯东北部的东北科学站进行实地研究，将为博士后研究员、来自美国的其他北极研究人员、俄罗斯的合作者。这些合作将用于将研究成果与俄罗斯的科学努力相结合。从拟议的研究中得出的科学发现将通过在科学期刊上发表文章、在国际会议上发表演讲以及更非正式地通过博士后研究员的职位进行广泛传播。的网页。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，为模型验证和扩大气候变化对北方森林生态系统的影响提供关键数据。