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: 2213624
• 负责人: Alexandra Ponette
• 金额: $ 65.12万
• 依托单位: University of North Texas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2213624&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。降雨要穿过林冠，必须沿着沿着两条“水文公路”流失：穿透雨（通过缝隙、树叶或树皮滴落的水）和茎流（沿着茎流的水）。当穿透雨和茎流流失时，它们会从树叶和树皮上冲走颗粒。虽然很小，但这些水文公路从树冠上冲刷下来的颗粒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物质。尽管如此，没有大规模的努力试图测量，规模和预测这些水文公路下降的颗粒的数量和质量。这些粒子通常是“失踪”，从目前的生态理论，森林如何循环元素。本研究旨在填补这一空白，通过监测风暴条件，穿透雨，茎流，和这些水文公路在北美主要森林类型的网站的颗粒。研究结果将把穿透雨和茎流与用于指导淡水和森林管理的共同模型联系起来。其成果将为外联工作提供信息，包括科学漫画和插图展览、“青年思想前沿”为中小学生撰写（并由其审查）的开放式文章，以及国际观众达数百万人的MinuteEarth频道的YouTube视频。该项目还将为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。对于北美大陆的40%和全球陆地表面的三分之一，降雨必须通过森林才能到达土壤表面。这种降雨被森林冠层分成两个净降雨通量：称为穿透雨（TF）的滴水通量和称为茎流（SF）的水流。有多少雨水通过沿着这些水文公路可以改变供水20- 50%，他们从树冠上携带的东西可以提供100公斤每公顷的各种材料到土壤表面每年。这些冠层生态水文过程处于气候和土地利用变化的前沿，因为启动陆地水文路径并向地表供应营养物/污染物的森林-降雨相互作用是受水文加剧影响的第一个生态系统要素。忽略这些通量，和他们的颗粒交通，引入错误的水和养分通量模型在第一点，陆地生态地球化学和水文循环englance，并可能级联这些错误通过downgradient过程。该项目旨在扩展当前的宏观系统生物学理解，包括穿透雨和树干流颗粒物浓度、通量和组成，具体解决3个主要目标：（1）估算森林类型间的净降雨（TF+SF）水和颗粒物质量通量;（2）表征颗粒物组成TF和SF的C：N：P（包括总C、有机C、黑C和微塑性C等C组分）;和（3）确定净降雨颗粒通量和组成的宏观系统变化的主要驱动因素。代表美国主要森林领域的国家生态观测站网络的11个站点对上述变量进行实地监测，可以测试现有功能特征与穿透雨和茎流动态实际整合到大陆到全球尺度的生态物理模型之间的联系。该项目还将支持博士后研究人员、硕士和博士生以及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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。