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.

该博士论文改进项目将研究环境条件变化对温带和其他非寒带地区森林丧失和随后泥炭地扩张的模式和机制的影响。 博士生将使用各种方法重建并比较上个世纪的火灾-气候-植被动态与过去千年发生的动态。 该项目的结果将揭示曾经森林覆盖但现在泥炭堆积的地区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，可能是由于与今天观察到的干旱条件和火灾频率相似。 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）超过了生态阈值，该项目将为有关土地管理最佳实践的决策提供重要的投入。 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，以确保项目结果可为协作土地使用决策提供信息。 PI 还将让 K-12 和大学生参与实践实地考察，从而为未来的科学家利用多种证据来调查环境变化的原因和后果做好准备。 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。该博士论文改进项目的总体目标是为森林生态系统火灾状况变化所导致的替代稳定状态的科学文献做出贡献。 这项研究将利用古生态学、树木生态学和群落生态学的方法，研究火灾对泥炭地-森林交错带不同时空尺度的生态系统结构的影响，泥炭地-森林交错带是一个过渡带，与林线一样，对火灾和气候的变化特别敏感。 该项目解决了以下问题：（1）后欧洲定居时期气候条件不同的火灾活动与定居前的火灾活动有何数量上的差异？ (2) 在最近的极端暖/干和冷/湿时期，火灾如何影响森林-泥炭地交错带的植被群落？ (3) 有哪些机制有利于从森林地向泥炭地转变？ 具体来说，博士生将利用树木年轮火痕年代、林分结构重建和沉积记录来回答这些问题。 此外，对对照和烧毁地点目前植被组成/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。 虽然该项目将重点关注巴塔哥尼亚西南部的森林泥炭地生态交错带，但该研究将为处理许多其他地区（包括美国的一些地区）环境变化的相互作用影响提供新的见解和方法。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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