Collaborative Research: RUI: Effects of N and P deposition on stoichiometry, structure, and function of whole-aquatic ecosystems (Bromeliaceae and Sarraceniaceae)

人类活动使全球向生物圈输入的氮和磷增加了一倍以上。北美和欧洲来自化石燃料和化肥的氮负荷比南半球要大得多。磷的负荷主要来自农业。它在北半球较小，但在热带地区尤为重要。然而，在中美洲和亚洲的热带森林中，氮的投入正在增加，并将在今后几十年继续增加。这些至关重要的要素输入的变化正在深刻地改变生态系统的结构和功能。生态系统对这些变化的反应仍然知之甚少。这个项目将通过研究猪笼草中存在的微型生态系统来填补这一知识空白。这些植物广泛分布在热带地区。它们可作为研究氮磷输入变化对生态系统结构和功能影响的模式环境。这项研究将利用猪笼草来促进我们对生态系统对环境变化的反应的理解。这项工作的结果将为受氮和磷负荷变化影响的生态系统的管理提供信息。它还将培养研究生和本科生，并将使大量高中生参与科学过程。本研究将通过在氮(N)和磷(P)沉积的大地理梯度上对植藻生态系统进行标准化的实地调查，量化元素模式。凤梨花和猪笼草的叶子形成隔间，可以装满雨水。这些隔室捕捉落叶和节肢动物的猎物，为无脊椎动物的食物网提供能量。这些系统提供了一个机会来测试营养沉积对整个生态系统和不同生态系统子模块（例如凤尾花和猪笼草组织、周围植物、水和大型无脊椎动物）的存量和营养通量的影响。这项研究将揭示整个生态系统的化学计量是否反映了当地氮和磷的有效性，或者化学计量比是否在沉积梯度上得到缓冲。总的来说，由植藻创造的明确的水生栖息地及其广泛的地理分布使研究人员能够在相对不变的栖息地中检查大规模的多样性模式、化学计量学和生态系统功能。这项研究将深入了解复制的整个生态系统内部和之间的氮和磷的地理分布。它还将测试在更传统的水生栖息地难以或不可能实现的规模上增加营养投入对生态系统的影响。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。

Human activity has more than doubled global nitrogen and phosphorus input to the biosphere. Nitrogen loading from fossil fuels and fertilizer is much larger in North America and Europe than in the Southern Hemisphere. Phosphorus loading comes mostly from agriculture. It is smaller in the Northern Hemisphere, but especially important in the tropics. In tropical forests of Central America and Asia, however, nitrogen input is increasing and will continue to do so in coming decades. Changes in the input of these critically important elements are profoundly changing ecosystem structure and function. Ecosystem responses to these changes remain poorly understood. This project will fill this knowledge gap by studying the miniature ecosystems that exist within pitcher plants. These plants are widely distributed across the tropics. They are useful as model environments to study the effects of changes in nitrogen and phosphorus inputs on ecosystem structure and function. This research will use pitcher plants to advance our understanding of ecosystem responses to environmental changes. Results of this work will inform management of ecosystems subject to changing nitrogen and phosphorus loading. It will also train graduate and undergraduate students, and will engage large numbers of high school students in the scientific process. This study will quantify elemental patterns by conducting standardized field surveys of phytotelmata ecosystems across large geographical gradients of nitrogen (N) and phosphorus (P) deposition. Leaves of tank bromeliads and pitcher plants form compartments that fill with rainwater. These compartments capture leaf litter and arthropod prey, which provide the energy to support a persistent food web of invertebrates. These systems provide an opportunity to test for nutrient deposition effects on the standing stocks and fluxes of nutrients for the whole ecosystem and within different ecosystem sub-modules (e.g., bromeliad and pitcher tissue, periphyton, water, and macroinvertebrates). This study will reveal whether whole-ecosystem stoichiometry reflects local availability of N and P, or whether stoichiometric ratios are buffered across deposition gradients. Overall, the well-defined aquatic habitats created by phytotelmata and their broad geographic distribution allow the researchers to examine large-scale patterns of diversity, stoichiometry, and ecosystem function in a relatively invariant habitat. This research will give insight into the geography of N and P within and across replicated whole ecosystems. It will also test the ecosystem-level consequences of increased nutrient inputs at scales difficult or impossible to achieve in more traditional aquatic habitats.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.