Collaborative Research: Hydrologic and Permafrost Changes Due to Tree Expansion into Tundra

合作研究：树木扩展到苔原导致的水文和永久冻土变化

• 批准号: 1725654
• 负责人: Valeriy Ivanov
• 金额: $ 42.28万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1725654&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrologic; Permafrost; Changes

The Arctic has been warming at an accelerating rate over the last several decades, and at the same time, trees and shrubs have been invading into tundra across the polar regions of Alaska, Canada, and Russia. These shifts in vegetation may, in turn, have the potential to influence regional hydrology and climate. The goal of this collaborative project is to combine approaches to study water, energy, and carbon cycling to understand inteactions between forest and tundra, including permafrost. The investigators will examine the effects of tree expansion, or encroachment, on movement of water between earth and air in an understudied forest-tundra boundary in the Siberian Arctic. The methods will include collection and analysis of field data, use of remote sensing, and modeling. The investigators will collaborate with scientists and students in Russia, and U.S. graduate students will be exposed to interdisciplinary research, perform field work in Russia, and have the opportunity to develop international collaborations. Various outreach activities will inform the public about results of this research and more generally, about the role of the Arctic in global environmental change. These activities include development of museum exhibits at the Museum of Natural History (MI), Orton Geological Museum (OH), Museum of Prairiefire (KS); public research seminars engaging indigenous people of Yamal (Russia); and documentaries showcasing this study in social and news media.The objective of this project is to study changes in hydrology and permafrost associated with tree expansion into tundra areas at the scales of both the field observational program and the regional Western Siberian Plain. The underlying hypotheses are that the tree encroachment process 1) alters the seasonality of heat exchange between the land and the atmosphere, 2) increases surface evapotranspiration, and 3) leads to warming of the subsurface with a progressive increase of thickness of soil seasonal thaw depth. The research builds on fifty years of observations in the areas with documented larch and spruce encroachment in the Polar Urals and southern Yamal Peninsula of Russia. The investigators will use a novel theory combined with comprehensive field observational data and remote sensing analyses to reveal the differences in heat exchange between the tundra and forest land covers. Pairs of field monitoring plots will be identified, with expansion of larch and spruce in one plot and no encroachment in the second of the pair. Field observations will include measurements of: micrometeorology, snow conditions, and radiative fluxes; tree-scale sap flows; snow water equivalent; soil temperature, moisture, and heat fluxes; active layer thickness; and soil composition. Field data will inform a model to derive surface energy budgets and heat fluxes. Remote sensing data from 1980s to present will connect local trends inferred from these field observations with regional characertistics of the Western Siberian Plain. Observed and modeled heat fluxes will be used in a comprehensive physical model to study the impact of vegetation encroachment on permafrost dynamics at both local and regional scales, and analysis of uncertainty will assess the reliability of the project findings.

过去几十年来，北极变暖速度不断加快，与此同时，树木和灌木侵入阿拉斯加、加拿大和俄罗斯极地地区的苔原。植被的这些变化反过来可能会影响区域水文和气候。该合作项目的目标是结合研究水、能源和碳循环的方法，以了解森林和苔原（包括永久冻土）之间的相互作用。研究人员将研究西伯利亚北极未充分研究的森林-苔原边界中树木的扩张或侵蚀对地球和空气之间水运动的影响。这些方法将包括现场数据的收集和分析、遥感的使用以及建模。研究人员将与俄罗斯的科学家和学生合作，美国研究生将接触跨学科研究，在俄罗斯进行实地工作，并有机会开展国际合作。各种外展活动将使公众了解这项研究的结果，更广泛地了解北极在全球环境变化中的作用。这些活动包括在自然历史博物馆（密歇根州）、奥顿地质博物馆（俄亥俄州）、草原之火博物馆（堪萨斯州）开发博物馆展品；亚马尔土著人民参与的公共研究研讨会（俄罗斯）；该项目的目标是在实地观测计划和西西伯利亚平原区域范围内，研究与树木扩展到苔原地区相关的水文和永久冻土的变化。基本假设是树木侵占过程 1) 改变了土地与大气之间热交换的季节性，2) 增加了地表蒸散量，3) 导致地下变暖，土壤季节性解冻深度厚度逐渐增加。这项研究建立在对极地乌拉尔地区和俄罗斯亚马尔半岛南部有记录的落叶松和云杉侵蚀地区五十年的观察基础上。研究人员将使用一种新颖的理论，结合全面的现场观测数据和遥感分析，揭示苔原和林地覆盖之间热交换的差异。将确定成对的田间监测样地，其中一个样地有落叶松和云杉扩张，而第二个样地没有侵占。现场观测将包括以下测量：微气象、雪况和辐射通量；树尺度的液流；雪水当量；土壤温度、湿度和热通量；有源层厚度；和土壤成分。现场数据将为模型提供信息，以得出表面能量预算和热通量。 20 世纪 80 年代至今的遥感数据将把这些实地观测推断出的当地趋势与西西伯利亚平原的区域特征联系起来。观测和模拟的热通量将用于综合物理模型，以研究植被侵蚀对当地和区域尺度永久冻土动态的影响，不确定性分析将评估项目研究结果的可靠性。

项目成果

Peak Runoff Timing Is Linked to Global Warming Trajectories

径流峰值时间与全球变暖轨迹有关

• DOI: 10.1029/2021ef002083
• 发表时间: 2021-08-01
• 期刊: Earth's Future
• 作者: Donghui Xu;V. Ivanov;Xiuyuan Li;T. Troy
• 通讯作者: T. Troy

Surface Energy Budgets of Arctic Tundra During Growing Season

北极苔原生长季节的表面能量预算

• DOI: 10.1029/2019jd030650
• 发表时间: 2019-07
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: El Sharif, Husayn;Zhou, Wenbo;Ivanov, Valeriy;Sheshukov, Aleksey;Mazepa, Valeriy;Wang, Jingfeng
• 通讯作者: Wang, Jingfeng

Spatiotemporal dynamics of encroaching tall vegetation in timberline ecotone of the Polar Urals Region, Russia

俄罗斯极地乌拉尔地区林线交错带侵入高大植被的时空动态

• DOI: 10.1088/1748-9326/ac3694
• 发表时间: 2021-12
• 期刊: Environmental Research Letters
• 影响因子: 6.7
• 作者: Zhou, Wenbo;Mazepa, Valeriy;Shiyatov, Stepan;Shalaumova, Yulia V.;Zhang, Tianqi;Liu, Desheng;Sheshukov, Aleksey;Wang, Jingfeng;El Sharif, Husayn;Ivanov, Valeriy
• 通讯作者: Ivanov, Valeriy

Streamflow, stomata, and soil pits: Sources of inference for complex models with fast, robust uncertainty quantification

水流、气孔和土坑：具有快速、稳健的不确定性量化的复杂模型的推理来源

• DOI: 10.1016/j.advwatres.2019.01.002
• 发表时间: 2019-03-01
• 期刊: Advances in Water Resources
• 影响因子: 4.7
• 作者: M. Dwelle;Jongho Kim;K. Sargsyan;V. Ivanov
• 通讯作者: V. Ivanov