Collaborative Research: MRA: Dew impacts on ecosystem carbon, energy and water fluxes at continental scale - a synthesis across NEON sites

控制植被中碳和水流动的过程是对气候变化的关键陆地表面反馈。虽然经常被忽视，但露水的形成可以使蒸腾通量减少25%，并可能提高植物在干旱系统中或在干旱期间对干旱或热胁迫的耐受性。此外，露水影响气孔间气体的吸收和交换，可能限制碳的增加，影响植物对某些病原体感染的敏感性，并支持附生植物群落。限制露水对这些生态系统过程的重要性是至关重要的，因为在变暖的情况下，预计会出现更大但频率更低的降雨事件和更干燥的空气，并可能导致露水输入的广泛减少。该项目将首次全面、宏观地评估露珠对干湿生态系统中碳、能量和水通量的影响。它将生成一个新的模块，用于在陆地表面模型中实现露水，从而进一步研究露水在从天气预报到微生物学等研究领域的影响。该项目将支持在波多黎各开展一项新的以实地为基础的海外研究项目，研究气候和生态系统的恢复能力。学生将在该项目中参加NEON项目的实地考察，并参加与当地科学家的研讨会和讨论。该项目将支持多达36名本科生，他们将主要从少数民族院校招募。该项目还将支持一名早期职业女性教师担任PI，培养三名博士生和八名高中生。露水的形成是一种无处不在的现象，在某些生态系统中几乎每天都会发生。露水通过抑制蒸腾、减少碳交换、影响冠层温度、反照率和局地蒸汽压差（VPD）对碳和水通量有可测量的影响。然而，以前的工作主要集中在干旱环境中叶片或植物水平的离散运动。在这里，第一个标准化的连续冠层尺度露水测量将使用红外辐射测量、GPS接收器的冠层含水量估算和NEON网络覆盖的水旱梯度上的叶片湿度传感器来产生。观测结果将用于直接评估露珠对生态系统通量的影响，并用于开发和实施一个生态系统模型，该模型考虑露珠对地表土壤水分、叶面水分吸收和能量平衡的影响。该项目将为露珠对生态系统过程的影响提供基本见解，并为露珠减少与气温上升和VPD相关的减少如何加剧生态系统水分压力提供关键约束。该奖项反映了美国国家科学基金会的法定使命，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。

The processes that control carbon and water flows through vegetation are critical land surface feedbacks on a changing climate. While often overlooked, dew formation can generate up to a 25% reduction in the transpiration flux and may improve plant tolerance of drought or heat stress in xeric systems or during dry periods in mesic systems. Furthermore, dew affects the uptake and exchange of gases across the stomata potentially limiting carbon gain, influences plant susceptibility to some pathogen infections, and supports epiphyte communities. Placing a constraint on the importance of dew to these ecosystem processes is critical since larger, but less frequent, rain events and drier air are expected under warming and may generate broad declines in dew inputs. This project will provide the first comprehensive, macroscale assessment of dew impacts on carbon, energy, and water fluxes across xeric to hydric ecosystems. It will generate a new module for dew implementation in land surface models, enabling further investigations of the impacts of dew in research areas ranging from weather forecasting to microbiology. The project will support the development of a new field-based study abroad program on climate and ecosystem resilience in Puerto Rico where students will participate in fieldwork at NEON sites and take part in workshops and discussions with local scientists. The project will support up to 36 undergraduate students for this, who will be recruited primarily from a minority-serving institution. The project will also support an early career female faculty member as PI, train three PhD students and eight high school students. The formation of dew is a ubiquitous phenomenon that can be an almost daily occurrence in some ecosystems. Dew has a measurable impact on carbon and water fluxes by suppressing transpiration, reducing carbon exchange, and impacting the temperature, albedo, and local vapor pressure deficit (VPD) of the canopy. However, previous work has largely focused on discrete campaigns in arid environments at the leaf or plant level. Here, the first standardized continuous canopy-scale measurement of dew will be generated using infrared radiometry, canopy water content estimates from GPS receivers, and leaf wetness sensors across a hydric to xeric gradient encompassed by the NEON network. The observations will be used for the direct assessment of dew impacts on ecosystem fluxes and for the development and implementation of an ecosystem model that accounts for the effects of dew on surface soil moisture, foliar water uptake, and energy balance. This project will provide fundamental insights into dew impacts on ecosystem processes and a critical constraint on how dew reduction associated with rising temperatures and VPD may exacerbate ecosystem water stress.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.