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留物的有机体(如土壤微生物)的营养限制模式的支配。通常情况下，植物和消费者受到相同营养物质的限制。然而，越来越多的证据表明，在一些生态系统中，不同的营养物质可能是限制因素，这种情况被称为不同的营养限制。这项研究考察了为什么在一些生态系统中出现了不同的营养限制，而在另一些生态系统中却没有，以及这对碳的利用和储存有什么影响。这些问题将使用从罗德岛到佐治亚州的四个湿地的施肥地块网络进行测试，包括淡水和盐碱地系统。所有地点的标准化采样将确保对植物和微生物生产力、磷循环和生态系统新陈代谢进行可比较的测量。预计磷矿化速率较高的生态系统将出现不同的营养限制，产生的碳储量将较少。这项研究对生态系统管理有影响，并提供了一个概念性框架，通过了解营养比例如何影响支配生态系统能量学的生物地球化学循环，在多个尺度上整合生态学研究。它包括通过一个研究指导计划，向代表不足的群体的学生做出承诺，包括美国印第安人和非裔美国人。

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.