Collaborative Research: Exploration of the mechanistic basis and biogeochemical implications of differential nutrient limitation among trophic levels

生态系统的结构和功能受植物和消耗植物残骸的生物（如土壤微生物）的营养限制模式的支配。通常，植物和消费者都受到同一种营养物质的限制。然而，越来越多的证据表明，在某些生态系统中，不同的营养物质可能成为限制因素，这种情况被称为差异营养限制。本研究探讨了为什么不同的营养限制发生在某些生态系统而不是其他生态系统中，以及在碳的利用和储存方面的后果。这些问题将在从罗德岛到乔治亚州的四个湿地（包括淡水和盐碱地）的一个施肥地块网络上进行测试。所有站点的标准化采样将确保植物和微生物生产力、磷循环和生态系统代谢的可比测量。预计在磷矿化率较高的生态系统中会出现不同的营养限制，从而产生较少的碳储量。该研究对生态系统管理具有重要意义，并通过了解营养比例如何影响控制生态系统能量学的生物地球化学循环，为在多个尺度上整合生态研究提供了一个概念框架。它包括通过一个研究指导项目，向包括美国印第安人和非洲裔美国人在内的代表性不足群体的学生提供帮助。

The structure and function of ecosystems is governed by patterns of nutrient limitation of plants and those organisms that consume plant remains, such as soil microbes. Often, plants and consumers are limited by the same nutrient. However, increasing evidence indicates that different nutrients can be limiters in some ecosystems, a situation known as differential nutrient limitation. This study examines why differential nutrient limitation occurs in some ecosystems but not others, and what the consequences are with respect to the utilization and storage of carbon. These questions will be tested using a network of fertilized plots in four wetlands from Rhode Island to Georgia, including both freshwater and saline systems. Standardized sampling at all sites will ensure comparable measurements of plant and microbial productivity, phosphorus cycling and ecosystem metabolism. It is expected that differential nutrient limitation will occur in ecosystems with higher rates of phosphorus mineralization and will yield less carbon storage. This study has implications for ecosystem management and provides a conceptual framework to integrate ecological studies at multiple scales by understanding how nutrient ratios affects the biogeochemical cycles that govern ecosystem energetics. It includes a commitment to students from under-represented groups, including American Indians and African Americans, through a research mentoring program.