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

通过植被控制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，露水的形成可以产生高达25%的蒸腾通量减少，并可能提高植物的耐旱性或热胁迫在干旱系统或在干旱期间在中温系统。此外，露水影响气孔的气体吸收和交换，可能限制碳的获得，影响植物对某些病原体感染的敏感性，并支持真菌群落。限制露水对这些生态系统过程的重要性至关重要，因为在变暖的情况下，预计会出现更大但不太频繁的降雨事件和更干燥的空气，并可能导致露水投入的广泛下降。该项目将提供第一个全面的，宏观尺度的评估露水对碳，能量和水通量在干旱到潮湿的生态系统的影响。它将产生一个新的模块，用于在陆地表面模型中实施露水，从而能够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发一个新的基于实地的气候和生态系统恢复力留学项目，学生将参加氖现场的实地考察，并参加研讨会和与当地科学家的讨论。该项目将为此支持多达36名本科生，他们将主要从为少数群体服务的机构招募。该项目还将支持一名早期职业女性教员担任PI，培训三名博士生和八名高中生。露水的形成是一种普遍存在的现象，在某些生态系统中几乎每天都会发生。露水通过抑制蒸腾作用、减少碳交换、影响冠层温度、蒸腾速率和局部水汽压亏缺（VPD），对碳通量和水通量产生可测量的影响。然而，以前的工作主要集中在干旱环境中的叶或植物水平上的离散运动。在这里，第一个标准化的连续冠层尺度的露水测量将使用红外辐射测量，冠层水分含量的GPS接收器估计，和叶片湿度传感器横跨一个由氖网络所涵盖的水分到干旱梯度。观测结果将用于直接评估露水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，该模型考虑了露水对表层土壤水分、叶面吸水和能量平衡的影响。该项目将提供有关露水对生态系统过程的影响的基本见解，以及与温度升高和VPD相关的露水减少如何加剧生态系统水压力的关键约束。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。

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.