Riparian shrub expansion: Linkages to permafrost, hydrology and soil microbes

河岸灌木扩张：与永久冻土、水文学和土壤微生物的联系

• 批准号: 1630360
• 负责人: Anna Liljedahl
• 金额: $ 6.19万
• 依托单位: University of Alaska Fairbanks 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: 2016-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1630360&HistoricalAwards=false
• 关键词: Riparian; shrub; expansion; Linkages; permafrost

The climatic drivers and landscape-scale patterns of recent Arctic shrub expansion are well understood, while the biogeochemical and physical mechanisms controlling shrub recruitment and growth remain unclear. The biogeophysical characteristics associated with tall shrub expansion near streams could potentially explain the documented increases in carbon and nutrient export from large Arctic rivers through the underlying processes of widespread permafrost degradation and increased subsurface flow. Additionally, occurrences of tall shrubs could be used as a readily measured proxy for subsurface properties both across space and time using remote sensing. If our observations hold true in other stream environments, the information has the potential to provide novel hydrological, permafrost, and biological process insights to complement the extensive literature on increasing Arctic shrub cover. Preliminary measurements of differential runoff in Arctic tundra link tall shrubs along riparian corridors to losing stream sections (streams with decreasing discharge downstream), whereas gaining or maintaining stream sections (increasing discharge downstream) lack tall shrubs.This award will support measurements to test whether the formation of a talik (permafrost-free ground) and a downward hydrologic gradient creates a biogeochemical subsurface environment that favors shrub recruitment and growth, which, in turn, results in patterns of tall shrub distribution coinciding along losing stream reaches. This team will measure additional streams with differing gradients, bed morphologies, and substrates to test the statistical significance of their preliminary observation that tall shrubs indicate losing streams, and to expand measurements to include shrub height, cover, biomass, Leaf Area Index (LAI), permafrost, and soil microbial communities. The award will support three early career researchers to gather background data to enable them to explore a potentially transformative idea to set the foundation to examine the processes linking shrubs, permafrost, hydrology and microbiology. The results of this work would be disseminated directly to land management and private organizations.

众所周知，最近北极灌木扩张的气候驱动因素和景观规模模式，而控制灌木募集和生长的生物地球化学和物理机制尚不清楚。与河流附近的高灌木膨胀相关的生物地球体物理特征可能可以解释通过大量多年冻土降解和地下流量增加的碳和养分从大北极河流出口的增加。此外，使用遥感的高灌木发生的出现可以用作跨空间和时间上的地下属性的易于测量的代理。如果我们的观察结果在其他流环境中成立，则该信息有可能提供新颖的水文，多年冻土和生物过程见解，以补充有关增加北极灌木覆盖的广泛文献。北极苔原中差异径流的初步测量沿河岸走廊连接高灌木，沿河岸走廊连接到失去的溪流区域（流下游下游的流动流），同时获得或保持流截面或维持流动部分（增加下游排放）缺乏这些高灌木的奖励，以测试始终的水平（始终阶层），以测试始终的talik talik frol of talik frestient of talik frestreque-frree frree frree frree frore frore frree，生物地球化学的地下环境有利于灌木募集和生长，这反过来又导致了沿损失的河流河流的高灌木分布的模式。该团队将测量具有不同梯度，床形态和底物的其他流，以测试其初步观察的统计意义，即高灌木表明流量表明流量流失，并扩大测量值以包括灌木高度，覆盖，生物质，叶子面积，叶子区域指数（LAI），多年冻土和土壤微生物社区。该奖项将支持三个早期的职业研究人员收集背景数据，以使他们能够探索一个潜在的变革思想，以奠定基础，以检查将灌木，多年冻土，水文学和微生物学连接起来的过程。这项工作的结果将直接传播给土地管理和私人组织。