Collaborative Research: MRA: A functional model of soil organic matter composition at continental scale

有机物是大多数土壤的组成部分，为社会提供了不成比例的关键服务。土壤有机质影响肥力和植物生长、水质和水量以及全球气候，因为它在储存碳和养分以及在分解过程中释放它们方面发挥作用。土壤有机质分布及其功能的预测研究已经进行了世纪的探索。影响土壤有机质的生态系统特性在小的和大的空间尺度上变化很大，许多以前的研究都集中在单一的土壤类型或地理区域。科学家们继续争论土壤有机物质的性质以及为什么它会持续存在，因为微生物不可避免地会在几天到几千年的时间内分解它。该项目旨在调和以前关于土壤有机质组成的争论，以及控制其分解和向植物提供氮的能力的物理，化学和生物因素。这项研究将联合收割机结合丰富的现有数据与新的样本和测量从国家生态观测网络（氖），监测网络，包括不同的网站在美国研究人员将测试一个新的定量框架，以预测土壤碳和氮循环，通过纳入多个权衡环境特征在地方到大陆规模。该项目将培训研究生和本科生，包括来自科学界代表性不足群体的学生，并将为普通教育受众编制与土壤有关的课程。许多与土壤有机质有关的有影响力的科学概念都是在单一生态系统类型中发展起来的，并且很难预测其在大陆尺度上的分布和动态。叶经济学谱表明，植物多样性的许多方面沿着一个基本的性状变异轴崩溃，对应于投资回报的快与慢。然而，土壤的巨大异质性和缺乏全面和标准化的数据，阻碍了努力发展一个类似的简单框架预测土壤地球化学过程。该项目将测试土壤有机质性质和循环的变化是否可以用生态系统变化的三个基本轴来解释，这三个基本轴对应于快和慢的生物地球化学速率，每个轴都与气候、矿物、植物、微生物和有机分子之间的相互作用有关，这得到了理论和初步数据的支持。考虑个别土壤样品的组成沿着每个轴，和他们的共同影响的过程速率，可能有助于调和的重要性，在以前的工作中表现出的有机质持久性的不同机制，从而提高预测的关键生态系统功能，土壤有机质提供。为了测试这个模型，研究人员将收集有机物分子组成，地球化学和矿物学，短期和长期地球化学过程速率以及微生物功能基因的新测量结果，这些测量结果利用了现有和正在进行的数据以及从氖站点收集的样本。该项目将包括招聘，教育和培训未来的科学，工程，技术和政策劳动力和领导力，以追求区域到大陆规模的生物学基础研究，以及机会，让不同的学习者和教育工作者社区参与区域到大陆规模的研究和氖的使用。该奖项反映了NSF的法定使命，并被认为值得支持，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。

Organic matter is a component of most soil that provides disproportionate and critical services to society. Soil organic matter influences fertility and plant growth, water quality and quantity, and global climate, due to its roles in storing carbon and nutrients and releasing them during decomposition. Predicting the distribution and functions of soil organic matter remains challenging despite more than a century of research on this topic. The ecosystem properties that influence soil organic matter vary tremendously over small and large spatial scales, and many previous studies have focused on a single soil type or geographic region. Scientists continue to debate the nature of soil organic matter and why it persists, given that microorganisms can inevitably decompose it over timescales of days to millennia. This project aims to reconcile previous debates regarding what soil organic matter consists of, and the physical, chemical, and biological factors that control its decomposition and capacity to supply nitrogen to plants. The study will combine a wealth of existing data with new samples and measurements from the National Ecological Observatory Network (NEON), a monitoring network including diverse sites across the U.S. Researchers will test a new quantitative framework to predict soil carbon and nitrogen cycling by incorporating multiple trade-offs in environmental characteristics at local to continental scales. The project will train graduate and undergraduate students, including those from underrepresented groups in science, and will develop soil-related curricula for a general educational audience. Many influential scientific concepts related to soil organic matter were developed within single ecosystem types and struggle to predict its distribution and dynamics at continental scale. The leaf economics spectrum showed that numerous aspects of plant diversity collapse along a fundamental axis of trait variation corresponding to fast vs. slow return on investment. However, the tremendous heterogeneity of soil and the lack of comprehensive and standardized data has stymied efforts to develop a similarly simple framework for predicting soil biogeochemical processes. This project will test whether variation in soil organic matter properties and cycling can be explained by three fundamental axes of ecosystem variation corresponding to fast and slow biogeochemical rates, each linked to interactions among climate, minerals, plants, microbes, and organic molecules, as supported by theory and preliminary data. Consideration of the composition of individual soil samples along each axis, and their joint influence on process rates, may help reconcile the importance of distinct mechanisms of organic matter persistence demonstrated in previous work, and thereby improve prediction of critical ecosystem functions that soil organic matter provides. To test this model, the researchers will collect new measurements of organic matter molecular composition, geochemistry and mineralogy, short- and long-term biogeochemical process rates, and microbial functional genes that leverage existing and ongoing data and sample collection from NEON sites. The project will include recruitment, education, and training of the future scientific, engineering, technical, and policy workforce and leadership needed to pursue basic research on regional to continental scale biology, as well as opportunities to engage a diverse community of learners and educators in regional to continental scale research and the use of NEON.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.