SG: Can green infrastructure maximize ecosystem processes related to nitrogen?

氮污染引起许多环境和人类健康问题。其中包括有害藻华、酸雨和烟雾。在城市里，化石燃料的燃烧和化肥的施用给雨水增加了大量的氮。城市基础设施向下游输送雨水，可能会因过量的氮污染下游生态系统。利用生态过程从雨水中去除氮的基于自然的设计可能提供一个解决方案。这些绿色基础设施设计在全球城市中很受欢迎。然而，它们的有效性仍然存在疑问。绿色基础设施的设计是否应该尽可能地模仿自然生态系统？或者土壤和物种的新组合能更有效地减轻污染吗？本研究将通过研究犹他州盐湖城几种类型的雨水管理设施来寻求这些问题的答案。本研究结果将为雨水管理系统的设计提供有益的指导。它也有可能推进对氮循环的基本理解。研究人员还将开展广泛的公共宣传和教育活动，以突出生态过程在城市空间中的重要性。科学界目前缺乏一个理论框架来指导设计最大限度地保留氮的生态系统。这主要是由于生态系统中氮循环的复杂性。研究人员提出了量化生态系统科学的两个关键范式：生物多样性-生态系统功能和热力学生态化学计量学对氮保持的相对影响。该项目将在两套复制的雨水管理实验设施以及邻近自然区域的复制地块中，对事件尺度和季节尺度上氮保留过程（微生物和植物吸收、植物生物量和土壤氮积累以及永久气体去除）的速率进行量化。第一个实验设施包括9个地块，种植了三个级别的植物功能多样性。第二类包括8个样地，其植物群落组成分为两个层次：观赏植物和原生旱适应植物。研究人员假设，如果与快速资源获取相关的生理性状是氮循环的重要驱动因素，那么具有高植物多样性和/或干旱适应性状的地块将具有更高的氮保留。此外，研究人员假设，如果生物多样性是这些过程的重要驱动因素，那么不同样地之间以及样地建立后随着时间的推移，微生物群落多样性的变化将与更高的氮固定化和反硝化作用相关。相反，如果生物多样性不是生态系统尺度氮通量的重要驱动因素，我们预计会发现保留率遵循热力学和化学计量模型，在植物群落之间没有显著差异。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。

Nitrogen pollution causes many environmental and human health problems. These include harmful algal blooms, acid rain and smog. In cities, fossil fuel burning and fertilizer application add large amounts of nitrogen to stormwater. City infrastructure carries stormwater downstream, which may pollute downstream ecosystems with excess nitrogen. Nature-based designs that use ecological processes to remove nitrogen from stormwater may provide a solution. These green infrastructure designs are popular in cities globally. Questions remain, however, about their effectiveness. Should green infrastructure design mimic natural ecosystems as closely as possible? Or can new combinations of soils and species more effectively mitigate pollution? This research will seek answers to these questions by studying several types of stormwater management facilities in Salt Lake City, UT. Results from this research will provide useful guidance to the design of stormwater management systems. It also has the potential to advance fundamental understanding of the nitrogen cycle. Researchers will also conduct extensive public outreach and educational activities to highlight the importance of ecological processes in urban spaces.The scientific community currently lacks a theoretical framework to guide design of ecosystems that maximize nitrogen retention. This is due largely to the complexity of nitrogen cycling in ecosystems. The researchers propose to quantify the relative influence of two key paradigms of ecosystem science on nitrogen retention: biodiversity-ecosystem function and thermodynamic ecological stoichiometry. The project will involve quantifying rates of nitrogen retention processes (microbial & plant uptake, plant biomass and soil nitrogen accumulation, and permanent gaseous removal) over event-scale and seasonal-scale in two sets of replicated stormwater management experimental facilities, as well as replicate plots in an adjacent natural area. The first experimental facility includes nine plots planted with three levels of plant functional diversity. The second includes eight plots with two levels of plant community composition: ornamental vs. native, xeric-adapted species. Researchers hypothesize that plots with high plant diversity and/or xeric-adapted traits will have higher nitrogen retention if physiological traits related to rapid resource acquisition are an important driver of nitrogen cycling. Further, researchers hypothesize that variation in microbial community diversity across plots and over time following plot establishment will correlate with higher nitrogen immobilization and denitrification if biodiversity is an important driver of these processes. Conversely, if biodiversity is not an important driver of ecosystem scale nitrogen fluxes, we expect to find retention rates follow thermodynamic and stoichiometric models without significant variation across plant communities.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.