Arctic Observing Networks: Collaborative Research: ITEX AON - understanding the relationships between vegetation change, plant phenology, and ecosystem function in a warming Arctic

北极观测网络：合作研究：ITEX AON - 了解北极变暖中植被变化、植物物候和生态系统功能之间的关系

• 批准号: 1504141
• 负责人: Jeffrey Welker
• 金额: $ 37.54万
• 依托单位: University of Alaska Anchorage Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-15 至 2021-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1504141&HistoricalAwards=false
• 关键词: Arctic; Observing; Networks; Collaborative; Research

Arctic ecosystems are changing in response to arctic warming, which is proceeding more than twice as fast as the global average. The International Tundra Experiment (ITEX) was established in the early 1990s to understand the effects of warming and environmental variability on tundra vegetation properties and ecosystem function. The ITEX program has been extremely valuable for detection of changes in tundra plant and ecosystem responses to experimental warming and to background climate change across sites that span the major ecosystems of the Arctic. In 2007, the Alaskan and Greenland ITEX sites were combined into an Arctic Observatory Network (AON). The current ITEX AON project will continue to document and understand Arctic terrestrial vegetation change and its ecosystem consequences by maintaining the long-term datasets of the ITEX-AON. The warming experiment of ITEX-AON allows us to assign the cause for observed changes in response to warming instead of relying on simple correlations. This project provides urgently needed data on changes in vegetation and the importance of these changes for ecosystem services from a variety of Arctic ecosystems. This project will provide training for postdoctoral, graduate and undergraduate students in the emerging fields of remote sensing, cybertechnology and big-data analysis. The project will include outreach activities through strong relationships with the CLEO Institute in Miami; the Grand Valley State University Regional Math and Science Center; and K-12 school systems in Miami, Anchorage, Grand Rapids and El Paso. All data from this project are and will be freely available at the NSF Arctic Data Center.The core datasets of the proposed research include manual observations of phenology, vegetation structure and composition, and ecosystem function (carbon flux and nutrient cycling) on long-term ITEX control and experimental warming plots, repeat measurement of vegetation plots on the long-term 1 km2 vegetation grids, and a multifactor warming/moisture experiment in Greenland. In 2009, the sampling scheme was expanded to include a larger spatial component to amplify the value of the measurements collected. This expansion included the addition of phenocams, automated mobile sensor platforms, and medium-scale aerial imagery. The automated platforms measure a suite of vegetation surface properties with minimal effort across focal transects spanning strong moisture and microtopographic gradients at a near-daily frequency. These measurements capture the fine-scale changes in vegetation over the growing season that are missed by lower frequency manual measurements and provide a bridge between manual measurements and aerial imagery. Medium-scale aerial imagery, using Kite Aerial or Unmanned Aerial Vehicles, is acquired throughout the growing season for scaling of manual and automated measurements; satellite imagery is referenced to medium-scale aerial imagery to aid scaling of responses to the regional level. In the newest phase of AON ITEX, we are particularly focused on understanding the relationship between landscape subsidence as a result of permafrost thaw and vegetation structure and function because of the potential for significant positive feedbacks to climate change.

北极生态系统正在因北极变暖而发生变化，其速度是全球平均速度的两倍多。国际冻土带实验（ITEX）建立于20世纪90年代初，旨在了解气候变暖和环境变率对冻土带植被特性和生态系统功能的影响。ITEX项目对于探测冻土带植物和生态系统对实验性变暖的反应以及跨越北极主要生态系统的地点的背景气候变化具有极其重要的价值。2007年，阿拉斯加和格陵兰的ITEX站点合并为北极观测网（AON）。目前的ITEX AON项目将继续通过维护ITEX-AON的长期数据集来记录和了解北极陆地植被变化及其生态系统后果。ITEX-AON的变暖实验使我们能够为响应变暖而观测到的变化分配原因，而不是依赖于简单的相关性。该项目提供了迫切需要的关于植被变化的数据，以及这些变化对各种北极生态系统的生态系统服务的重要性。该项目将为遥感、网络技术和大数据分析等新兴领域的博士后、研究生和本科生提供培训。该项目将包括通过与迈阿密CLEO研究所的牢固关系开展外联活动；大峡谷州立大学区域数学与科学中心；以及迈阿密、安克雷奇、大急流城和埃尔帕索的K-12学校系统。这个项目的所有数据都将在美国国家科学基金会北极数据中心免费提供。研究的核心数据集包括ITEX控制区和试验区长期增温样地物物学、植被结构和组成、生态系统功能（碳通量和养分循环）的人工观测数据集，1 km2植被网格长期植被样地重复测量数据集，以及格陵兰多因子增温/湿润实验数据集。2009年，采样方案扩大到包括更大的空间成分，以扩大所收集的测量值。这一扩展包括增加了现象摄像头、自动移动传感器平台和中等规模的航空图像。自动化平台以接近每日的频率测量一套植被表面特性，只需最小的努力即可跨越焦点横断面，跨越强湿度和微地形梯度。这些测量捕获了低频率人工测量无法捕捉到的植被在生长季节的细微变化，并在人工测量和航空成像之间架起了一座桥梁。在整个生长季节，使用风筝或无人机获取中等尺度航空图像，用于手动和自动测量的缩放；卫星图像参考了中等比例尺的航空图像，以帮助对区域一级的响应进行缩放。在AON ITEX的最新阶段，我们特别关注永久冻土融化导致的景观沉降与植被结构和功能之间的关系，因为这可能对气候变化产生重大的正反馈。