Collaborative Research: MRA: Particulates in canopy flowpaths: A missing mass flux at the macrosystem scale?

合作研究：MRA：冠层流动路径中的颗粒物：宏观系统尺度上缺失的质量通量？

• 批准号: 2213623
• 负责人: John Van Stan
• 金额: $ 224.28万
• 依托单位: Cleveland State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2213623&HistoricalAwards=false
• 关键词: Collaborative; Research; MRA; Particulates; canopy

Forests cover one-third of the land on Earth. For rainfall to pass through the forest canopy, it must drain along two “hydrologic highways”: throughfall (water that drips through gaps and from leaves or bark); and stemflow (water that runs down stems). As throughfall and stemflow drain, they wash particles from leaves and bark. Although tiny, particles washed from the canopy by these hydrologic highways can constitute a significant chemical input to the soil, and represent a wide range of materials, from nutrients to pollutants. Despite this, no large-scale effort has sought to measure, scale, and predict the amount and quality of particles descending down these hydrologic highways. These particles are generally “missing” from current ecological theory of how forests cycle elements. This study seeks to fill this gap by monitoring storm conditions, throughfall, stemflow, and the particles in these hydrologic highways across sites representing major forest types in North America. Results will link throughfall and stemflow to common models used to inform freshwater and forest management. Outcomes will inform outreach efforts, including science comics and illustration exhibits, open-access articles written for (and reviewed by) primary and secondary school children with Frontiers for Young Minds, and YouTube videos with MinuteEarth, a channel with an international viewership of millions. The project will also provide research experiences to members of underrepresented groups to broaden participation in science.For 40% of the North American continent and one-third of global land surface, rainfall must pass through forests to reach the soil surface. This rainfall is partitioned by the forest canopy into two net rainfall fluxes: a drip flux called throughfall (TF), and a flow of water down stems, called stemflow (SF). How much rain travels along these hydrologic highways can alter water supply by 20-50%, and what they carry from the canopy can supply 100 kg per hectare of various materials to the soil surface each year. These canopy ecohydrological processes are on the front line of climate and land use change, being that the forest-rainfall interactions that initiate terrestrial hydrological pathways and supply nutrients/pollutants to the surface are the first ecosystem elements impacted by hydrologic intensification. Ignoring these fluxes, and their particulate traffic, introduces error in water and nutrient flux models at the first point where terrestrial biogeochemistry and hydrological cycles entwine, and which may cascade those errors through downgradient processes. This project aims to extend current macrosystem biological understanding to include throughfall and stemflow particulate concentrations, fluxes and composition, specifically addressing 3 major objectives: (1) estimate the net rainfall (TF+SF) water and particulate mass flux across forest types; (2) characterize the particulate composition (C:N:P, including C components like total C, organic C, black C, and microplastic C) of TF and SF; and (3) identify major drivers of macrosystem variability in net rainfall particulate flux and composition. Field monitoring of the above variables across 11 sites of the National Ecological Observatory Network representing the major US forest domains allows links to be tested between existing functional characteristics and the practical integration of throughfall and stemflow dynamics into continental-to-global scale biogeophysical models. The project will also support research training of a postdoctoral researcher, masters and doctoral students, and a technician.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.

森林覆盖了地球上三分之一的土地。为了让雨水穿过森林树冠，它必须沿着两条“水文高速公路”排干：穿透雨水(从林隙和树叶或树皮上滴下来的水)和树干径流(沿着树干流下的水)。当穿透雨和茎流排干时，它们洗去树叶和树皮上的颗粒。被这些水文公路从树冠上冲刷下来的颗粒虽然很小，但可以构成对土壤的重要化学输入，并代表从营养物质到污染物的广泛材料。尽管如此，没有大规模的努力试图测量、衡量和预测沿这些水文公路下降的颗粒物的数量和质量。这些颗粒通常在当前关于森林如何循环元素的生态学理论中“缺失”。这项研究试图通过监测代表北美主要森林类型的这些水文公路上的风暴条件、穿透雨、树干径流和颗粒来填补这一空白。结果将把穿透降雨和树干径流与用于为淡水和森林管理提供信息的常见模型联系起来。成果将为外联工作提供信息，包括科学漫画和插图展览，为中小学生撰写(并由他们审阅)《青年思维前沿》的开放获取文章，以及与MinuteEarth频道合作的YouTube视频，MinuteEarth频道拥有数百万国际观众。该项目还将向代表性不足的群体成员提供研究经验，以扩大对科学的参与。北美大陆40%的地区和全球陆地表面的三分之一，降雨必须穿过森林才能到达土壤表面。这些降雨被森林树冠分割成两个净降雨通量：一种是称为穿透雨(Tf)的滴水通量，另一种是沿着树干向下流动的水，称为树干径流(SF)。这些水文公路上的降雨量可以改变20%-50%的供水，它们从树冠上携带的东西每年可以为土壤表面提供每公顷100公斤的各种物质。这些冠层生态水文过程处于气候和土地利用变化的最前线，因为森林-降雨相互作用启动了陆地水文路径，并向地表提供营养物质/污染物，是受到水文强化影响的第一个生态系统要素。忽略这些通量及其颗粒交通，会在陆地生物地球化学和水文循环交织的第一个点给水和营养通量模型带来误差，并可能通过下行过程将这些误差级联起来。该项目旨在扩展目前对大系统生物学的了解，包括穿透雨和树干径流中的颗粒浓度、通量和组成，具体涉及三个主要目标：(1)估算不同森林类型的净降雨量(Tf+SF)水分和颗粒质量通量；(2)表征Tf和SF的颗粒组成(C：N：P，包括总C、有机C、黑C和微塑料C等C组分)；以及(3)确定净降雨颗粒物通量和组成中宏观系统变异的主要驱动因素。对代表美国主要森林领域的国家生态观测网11个地点的上述变量进行现场监测，可以测试现有功能特征与将穿透雨和树干径流动力学实际整合到大陆到全球尺度的生物地球物理模型之间的联系。该项目还将支持一名博士后研究员、硕士和博士后学生以及一名技术人员的研究培训。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为值得支持。