Doctoral Dissertation Research: Understanding and Managing Ecosystem Change at the Forest-Peatland Ecotone

博士论文研究：理解和管理森林-泥炭地生态交错带的生态系统变化

• 批准号: 1806037
• 负责人: Andres Holz
• 金额: $ 1.75万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806037&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Understanding; Managing

This doctoral dissertation improvement project will investigate the impacts of changing environmental conditions on the patterns and mechanisms of forest loss and subsequent peatland expansion in temperate and other non-boreal regions. Using a variety of methods, the doctoral student will reconstruct and compare fire-climate-vegetation dynamics of the past century to those that have occurred over the past millennium. The results of this project will reveal whether once-forested but now peat-accumulating sites are novel ecosystems, or whether such transitions have occurred in the past in these regions, possible due to drought conditions and fire frequencies that are similar to those observed today. These results are of interest to land managers, who require tools to determine how best to manage altered ecosystems. By identifying whether (and which) ecological thresholds have been crossed, this project will provide crucial input for decision-making regarding best practices for land management. The doctoral student will work closely with regional land managers and other stakeholders, including land owners and educators, to ensure that project results are available to inform collaborative land use decisions. The PIs will also engage K-12 and college students in hands-on fieldwork, thus preparing future scientists to employ multiple lines of evidence in investigating the causes and consequences of environmental change. In addition, as a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising graduate student to establish a strong independent research career.The overarching objective of this doctoral dissertation improvement project is to contribute to the scientific literature on alternative stable states that result from changes in the fire regimes of forested ecosystems. Using methods from paleoecology, dendroecology, and community ecology, this research will examine fire-mediated effects on ecosystem structure at varying spatiotemporal scales at the peatland-forest ecotone, a transition zone that, like tree line, is particularly sensitive to changes in fire and climate. The project addresses the following questions: (1) How has fire activity during post-European settlement periods with distinct climate conditions differed quantitatively from that of pre-settlement conditions? (2) How has fire impacted the vegetation community of the forest-peatland ecotone during the most recent extreme warm/dry and cool/wet periods? (3) What are the mechanisms that favor a transition from forested to peat-accumulating lands in a site? Specifically, the doctoral student will use tree-ring fire scar dates, forest stand structure reconstructions, and sedimentary records to answer these questions. In addition, surveys of present-day vegetation composition/structure at control and burned sites will be paired with those of abiotic and biotic factors to uncover the mechanisms underlying the persistence of the peat-accumulating state. Although this project will focus on the forest-peatland ecotone of southwestern Patagonia, the research will provide new insights and approaches for dealing with the interactive effects of environmental change in many other regions, including some in the United States.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这个博士论文的改进项目将研究变化的环境条件对温带和其他非北方地区森林损失和随后泥炭地扩张的模式和机制的影响。使用多种方法，博士生将重建和比较过去一个世纪的火-气候-植被动态与过去一千年的动态。这个项目的结果将揭示曾经有森林但现在有泥炭聚集的地点是否是新的生态系统，或者这些地区过去是否发生过这种转变，可能是由于干旱条件和火灾频率与今天观察到的相似。这些结果引起了土地管理者的兴趣，他们需要工具来确定如何最好地管理改变的生态系统。通过确定是否（以及哪些）生态阈值已被越过，该项目将为有关土地管理最佳做法的决策提供关键输入。博士生将与区域土地管理者和其他利益相关者（包括土地所有者和教育工作者）密切合作，确保项目结果可用于协同土地使用决策。pi还将让K-12和大学生参与实地考察，从而为未来的科学家在调查环境变化的原因和后果时运用多种证据做好准备。此外，作为博士论文研究改进奖，该奖项将为有前途的研究生建立强大的独立研究生涯提供支持。本博士论文改进项目的总体目标是为森林生态系统火灾制度变化导致的替代稳定状态的科学文献做出贡献。利用古生态学、树木生态学和群落生态学的方法，本研究将在不同时空尺度上研究泥炭地-森林过渡带的火灾对生态系统结构的影响。泥炭地-森林过渡带是一个过渡带，与树线一样，对火灾和气候变化特别敏感。该项目解决了以下问题：(1)在气候条件不同的欧洲人定居后时期的火灾活动与定居前的火灾活动在数量上有何不同？(2)在最近的极端暖/干和冷/湿时期，火灾如何影响森林-泥炭地过渡带的植被群落？(3)什么机制有利于一个地点从森林地向泥炭地过渡？具体来说，博士生将使用树木年轮火灾疤痕日期，林分结构重建和沉积记录来回答这些问题。此外，对控制区和燃烧区当前植被组成/结构的调查将与非生物和生物因素的调查相结合，以揭示泥炭积累状态持续存在的机制。虽然这个项目将集中在巴塔哥尼亚西南部的森林-泥炭地过渡带，但这项研究将为处理许多其他地区（包括美国的一些地区）环境变化的相互影响提供新的见解和方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Emergent freeze and fire disturbance dynamics in temperate rainforests

• DOI: 10.1111/aec.12751
• 发表时间: 2019-08
• 期刊: Austral Ecology
• 影响因子: 1.5
• 作者: B. Buma;E. Batllori;S. Bisbing;A. Holz;S. Saunders;A. Bidlack;Megan K. Creutzburg;D. DellaSala;D. Gregovich;P. Hennon;J. Krapek;M. Moritz;Kyla Zaret