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.

该博士学位论文的改进项目将研究改变环境条件对温带和其他非谷物地区森林损失的模式和随后的泥炭地扩张的影响。 使用多种方法，博士生将重建和比较上个世纪的火灾气候植被动态与过去千年中发生的动态。 该项目的结果将揭示曾经被遗产但现在泥炭蓄积的地点是新的生态系统，或者过去在这些地区是否发生过这种过渡，这是由于干旱条件和与当今观察到的那些相似的火灾而发生的。 这些结果对土地管理者来说是一个有趣的，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（以及哪个）生态阈值是否已经越过，该项目将为土地管理最佳实践提供至关重要的意见。 博士生将与区域土地经理和其他利益相关者（包括土地所有者和教育工作者）紧密合作，以确保可以使用项目结果来告知合作土地使用决策。 PI还将与K-12和大学生一起进行实践现场工作，从而使未来的科学家在调查环境变化的原因和后果时采用多种证据。 此外，作为博士学位论文研究改进奖，该奖项将提供支持，以使有前途的研究生能够建立强大的独立研究职业。该博士学位论文改进项目的总体目标是为替代性稳定状态的科学文献做出贡献，这些稳定状态是由于森林生态系统的火灾政策变化而导致的。 使用古生态学，树突生态学和社区生态学的方法，该研究将检查对泥炭地 - 森林 - 森林量表的不同时空尺度上对生态系统结构的影响，peatland-Forest Ecotone是一个过渡区，该过渡区（如树线）对火灾和气候的变化特别敏感。 该项目解决了以下问题：（1）在欧洲后定居期期间，具有不同气候条件的灭火活动与安排前条件有不同的不同之处？ （2）在最近的极端温暖/干燥/潮湿的时期，火如何影响森林 - 帕兰ecotone的植被社区？ （3）有哪些有利于从森林到泥炭蓄积土地过渡到地点的机制？ 具体来说，博士生将使用树环火疤痕日期，森林支架结构的重建和沉积记录来回答这些问题。 此外，对照和燃烧部位对当今植被组成/结构的调查将与非生物和生物因素的调查相结合，以发现泥炭蓄积状态持续存在的机制。 尽管该项目将重点放在巴塔哥尼亚西南部的森林 - 帕特兰ecotone上，但该研究将为处理许多其他地区的环境变化的互动效果提供新的见解和方法，包括美国的一些地区。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识优点和更广泛的crietia crietia的评估来通过评估来进行评估。

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