A NOVEL THEORETICAL AND QUANTITATIVE FRAMEWORK TO UNDERSTAND AND PREDICT SOIL CARBON STORAGE AND NITROGEN RECYCLING

土壤在全球碳循环中发挥着重要作用。以落叶或木屑形式进入土壤的碳可以休眠数百年至数千年，也可以作为微生物分解的副产品几乎立即释放到大气中。碳在土壤中的停留时间受土壤的物理和化学结构以及湿度和温度的影响，影响植物必需营养物质的有效性。通过使用从不同栖息地采集的土壤进行实验室实验，并与从一系列生物群系收集的观测数据进行比较，该项目将推断哪些因素在决定碳如何进入和离开土壤方面最重要，以及它们的相对重要性如何在环境梯度中变化。研究人员将使用新收集和分析的数据来完善土壤碳动态模型，目的是促进我们对环境条件、植被和土壤特征之间的相互作用如何驱动不同生态系统中的碳和氮循环的理解。该项目将邀请本科生和K-12教师为当地学区开发和维持一个土壤调查项目，包括在世界土壤日定期举行的公共活动。研究人员将开发一个基于土壤有机质动力学综合概念框架的开放获取生态系统模型（MEMS 2.0）。他们将通过对照实验、数据综合、统计分析和基于过程的建模来评估概念框架。他们将进行操纵土壤C和N循环驱动因素的实验，以评估不同的土壤特征对土壤C储存和N损失的影响。利用来自所有国家生态观测网络站点和其他现有数据集的土壤样品的土壤有机质和元素和同位素分析，他们将开发一个关系数据库，并使用传统的多元统计和结构方程模型验证他们的假设。然后，他们将使用美国各地的数据表校准MEMS 2.0模型。最后，MEMS 2.0将用于预测不同温度和降水条件下的碳氮动态。这个项目将有助于弥合建模者和实验家之间的历史鸿沟，并培养新一代科学家有效地跨越这些领域。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。

Soils play an important role in the global carbon cycle. Carbon that enters the soil as leaf litter or woody debris can lie dormant for hundreds to thousands of years, or it can be released to the atmosphere almost immediately as a byproduct of decomposition by microbes. The residence time of carbon in the soil, which impacts the availability of nutrients essential to plants, is influenced by the physical and chemical structure of the soil, and by moisture and temperature. Through laboratory experiments using soils harvested from different habitats, and a comparison with observational data collected from a range of biomes, this project will infer which factors are most important in determining how carbon moves into and out of soil, and how their relative importance changes across environmental gradients. The researchers will use newly collected and analyzed data to refine models of soil carbon dynamics, with the aim of advancing our understanding of how interactions between environmental conditions, vegetation, and soil characteristics drive carbon and nitrogen cycling across different ecosystems. The project will engage undergraduates and K-12 teachers to develop and sustain a Soil Inquiry project for the local School District, including a recurring public event on World Soil Day.The researchers will develop an open-access ecosystem model (MEMS 2.0) based a comprehensive conceptual framework for soil organic matter dynamics. They will evaluate the conceptual framework through a combination of controlled experiments, data synthesis, statistical analyses, and process-based modeling. They will perform experiments manipulating drivers of soil C and N cycling to evaluate the effects of different edaphic characteristics on soil C storage and N loss. Leveraging soil organic matter and elemental and isotopic analyses of soil samples from all the National Ecological Observatory Network sites and other existing datasets, they will develop a relational database and test their hypotheses using traditional multivariate statistics and structural equation modeling. They will then calibrate the MEMS 2.0 model using data form across the US. Finally, MEMS 2.0 will be used to forecast C and N dynamics under different temperature and precipitation regimes. This project will help to bridge the historical gap between modelers and experimentalists and train a new generation of scientists to effectively span these domains.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.