Collaborative Research: Understanding Ozone-Ecosystem Controls and Feedbacks across Landscapes through Leaf- and Canopy-Scale Measurements

这项研究将有助于更好地了解影响森林地区对流层臭氧变化的过程。 将使用新的分析工具收集关于大气层-树冠层气体交换和对臭氧的相关生态反应的全面观测资料。领导这项工作的跨学科科学家团队拥有大气化学，景观和生物生态学以及陆地-大气交换方面的专业知识，以及在现场和实验室环境中先进仪器设计和使用方面的广泛实验专业知识。该项目的结果有可能通过更好地代表生态系统对臭氧污染的反馈来改善空气质量建模。科学家团队计划在弗吉尼亚州中部的弗吉尼亚森林实验室（VFL）收集两年的连续数据，将臭氧通量测量与太阳诱导荧光（SIF），异构体分辨臭氧反应性生物有机化合物（BVOCs）以及冠层电导和二氧化碳交换的关键生态系统参数的冠层水平光合作用的观测相结合。 这些相同的变量将在叶尺度实验室实验中通过类似的仪器进行测量，实验中使用在典型的当地环境条件范围内在VFL突出的植物物种，其中将引起扰动以测试生态系统反馈。（1）进入冠层的臭氧通量与直接检测叶绿素分子荧光的SIF技术之间的相互作用是可以直接测量的，是独立的臭氧通量和气孔导度之间的相互作用，并有一个可区分的臭氧寿命的影响;（2）臭氧通量的冠层往往是由稀疏测量，但高度反应性的BVOCs控制。由这些BVOCs引起的进入树冠层的臭氧通量的变化可以通过其分子特性和浓度来量化;（3）：植物吸收臭氧导致以下三种可检测的重要臭氧生态系统反馈中的一种或多种：（a）臭氧吸收降低气孔导度，导致植物吸收臭氧的寿命更长;（B）臭氧吸收通过损害光合作用降低了冠层BVOC浓度，导致臭氧抵抗冠层内化学氧化的寿命延长;及（c）臭氧的吸收增加了BVOC的排放，导致臭氧抵抗冠层内化学氧化的寿命缩短。 这项研究的结果预计将产生新的观测约束之间的关系大气成分和生态系统functions.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

This research will help to develop a better understanding of the processes that influence tropospheric ozone variability in forested regions. New analytical tools will be used to collect comprehensive observations of the atmosphere-canopy exchange of gases and the associated ecological response to ozone. The interdisciplinary team of scientists who are leading this effort have expertise in atmospheric chemistry, landscape and organismal ecology, and land-atmosphere exchange, as well as broad experimental expertise in advanced instrumentation design and use in field and laboratory settings. The results of this project have the potential to improve air quality modeling by better representing ecosystem feedbacks to ozone pollution. The team of scientists plan to collect two years of continuous data at the Virginia Forest Laboratory (VFL) in central Virginia, coupling ozone flux measurements with observations of canopy-level photosynthesis by solar induced fluorescence (SIF), isomer-resolved ozone-reactive biogenic organic compounds (BVOCs), and critical ecosystem parameters of canopy conductance and carbon dioxide exchange. These same variables will be measured by analogous instrumentation in leaf-scale laboratory experiments using plant species prominent at the VFL under the range of typical local environmental conditions, in which perturbations will be induced to test for ecosystem feedbacks.The three hypotheses to be tested are: (1) Interactions between ozone flux to the canopy and the SIF technique, that directly detects fluorescence of chlorophyll molecules, are directly measurable, are independent from interactions between ozone flux and stomatal conductance and have a distinguishable effect on the ozone lifetime; (2) Ozone flux to the canopy is often controlled by sparsely measured but highly reactive BVOCs. Variability in ozone flux to the canopy caused by these BVOCs can be quantified by their molecular identities and concentrations; (3): Uptake of ozone by plants leads to one or more of 3 detectable and significant ozone-ecosystem feedbacks: (a) ozone uptake reduces stomatal conductance, leading to longer ozone lifetimes against plant uptake; (b) ozone uptake reduces canopy BVOC concentrations by impairing photosynthesis, leading to longer ozone lifetimes against within-canopy chemical oxidation; and (c) ozone uptake enhances BVOC emissions, leading to shorter ozone lifetimes against within-canopy chemical oxidation. The results of this research are expected to produce new observational constraints on relationships between atmospheric composition and ecosystem function.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.