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

氮污染造成了许多环境和人类健康问题。这些问题包括有害的藻类大量繁殖、酸雨和烟雾。在城市，化石燃料的燃烧和化肥的使用增加了雨水中的大量氮。城市基础设施向下游输送雨水，这可能会用过量的氮气污染下游生态系统。使用生态过程从雨水中去除氮的基于自然的设计可能会提供一个解决方案。这些绿色基础设施设计在全球城市很受欢迎。然而，关于它们的有效性仍然存在疑问。绿色基础设施设计是否应该尽可能地模仿自然生态系统？或者，新的土壤和物种组合能否更有效地缓解污染？这项研究将通过研究德克萨斯州盐湖城的几种类型的雨水管理设施来寻求这些问题的答案。研究结果将为雨水管理系统的设计提供有益的指导。它还有可能促进对氮循环的基本理解。研究人员还将开展广泛的公众宣传和教育活动，以强调城市空间生态过程的重要性。科学界目前缺乏一个理论框架来指导最大限度地保持氮的生态系统的设计。这在很大程度上是由于生态系统中氮素循环的复杂性。研究人员建议量化生态系统科学的两个关键范式对氮保持的相对影响：生物多样性-生态系统功能和热力学生态化学计量学。该项目将包括在两套重复的雨水管理实验设施和邻近自然区的重复小区中，量化事件尺度和季节尺度上的氮保持过程(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。第一个实验设施包括九个种植了三个水平的植物功能多样性的地块。第二部分包括八个地块，植物群落组成分为两个层次：观赏植物与原生旱生植物。研究人员假设，如果与快速获取资源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/或干旱适应特征的小区将具有更高的氮素保持能力。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，那么随着地块的建立，微生物群落多样性的变化将与更高的氮素固定和反硝化作用相关。相反，如果生物多样性不是生态系统规模氮通量的重要驱动因素，我们预计保留率将遵循热力学和化学计量模型，在不同植物群落之间没有显著差异。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.