EAR-PF: Assessing the Potential for Enhanced Duration of Soil Carbon Storage via Anaerobic Microsites from the Plant Rhizosphere to Catchment Scale

Hannah Naughton博士获得了NSF EAR博士后奖学金，与劳伦斯·伯克利国家实验室合作，在加州大学伯克利分校研究缺氧微站点对土壤碳循环的影响。旱地土壤，例如典型的农田土壤，被认为是完全氧化的，因此在微生物碳氧化为温室气体二氧化碳方面是无限的。然而，旱地土壤含有高达85%的厌氧孔隙空间，这阻碍了呼吸作用，并可能加剧甲烷等强有力的温室气体的释放。该研究金的目标是开发一个统计和地理空间模型，预测1)范围和2)沿着科罗拉多州东河从山坡到洪水平原的水文坡度的这些厌氧微站点的碳储量。该项目将开发一个概念框架，作为土地管理人员和科学家利用现成的遥感数据更好地了解其土壤中的碳动态的工具，从而最大限度地减少耗费时间和资金的田间土壤采样和定性。这种工具和通过这项工作产生的基本科学知识将改进对未来降水、温度和植被变化下土壤碳储量的预测和管理，扩展到计算碳信用，在传统和可持续农业技术之间做出决定，并更好地限制各国的陆地碳排放。该项目将通过直接指导、校园和实地宣传讨论罕见的土壤(和土壤)多样性以及通过加州大学伯克利分校的课程开发和教学，支持地球科学领域的妇女和其他少数群体。饱和条件和有机输入是两种沿坡度自然变化的条件，已知会耗尽土壤氧气，但根系在形成土壤氧化还原微异质性中的作用尚未得到测试。植物功能类型(PFT，例如灌木和草)根据地貌和地质对太阳辐射、水和养分可用性的控制而适应于景观位置。在地下，PFTs在根系特征和在土壤团聚体形成中的作用方面存在显著差异。East River以前的研究已经证明，基于遥感的地表和地下属性，PFT的分布是可预测的，这表明控制碳转化的土壤氧化还原微观异质性可能在更大的尺度上是可预测的。利用坡漫滩坡度评价景观特征、PFT分布、土壤物理特性和微生物代谢之间的关系，进而确定对土壤碳组成和储量的影响。这些关系将为利用激光雷达和高光谱数据预测厌氧微站点形成和由此产生的碳储存潜力的地理空间模型提供信息。指导和教学机会以及本项目的范围将为Naughton博士在一所本科院校的教员职位做好准备，她打算在那里继续研究微尺度土壤异质性对碳循环的影响，以及在更大空间尺度上预测和表现这一知识的方法。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Hannah Naughton has been granted an NSF EAR Postdoctoral Fellowship to study the impact of anoxic microsites on soil carbon cycling at the University of California, Berkeley, in collaboration with Lawrence Berkeley National Laboratory. Upland soils, e.g. a typical farm soil, are considered completely oxic and thus unlimited with respect to microbial carbon oxidation to the greenhouse gas, carbon dioxide. However, upland soils contain up to 85% anaerobic pore space that hinders respiration and potentially exacerbates the release of potent greenhouse gases like methane. The goals of this fellowship are to develop a statistical and geospatial model predicting 1) the extent, and 2) the carbon storage in these anaerobic microsites along a hillslope-to-floodplain hydrologic gradient in East River, Colorado. This project will develop a conceptual framework that could be used as a tool for land managers and scientists to better understand carbon dynamics in their soils using readily available, remotely sensed data, thus minimizing time- and money-intensive field soil sampling and characterization. Such a tool and the basic scientific knowledge generated through this work will improve prediction and management of soil carbon storage under changing precipitation, temperature and vegetation going into the future, with extensions to calculating carbon credits, deciding between conventional and sustainable farming techniques, and better constraining countries’ terrestrial carbon emissions. This project will support women and other minority groups in the Earth Sciences through direct mentorship, campus and field site outreach discussing the uncommonly known diversity of (and in) soils, and through course development and teaching at UC Berkeley. Saturated conditions and organic inputs, two conditions that naturally vary along hillslope gradients, are known to deplete soil oxygen, but the role of roots in forming soil redox microheterogeneity has not yet been tested. Plant functional types (PFTs, e.g. shrub vs. grass) are adapted to landscape positions according to geomorphic and geologic controls on solar radiation, water and nutrient availability. Below-ground, PFTs differ significantly in root traits and role in soil aggregate formation. Previous East River work has demonstrated that PFT distribution is predictable based on remotely sensed surface and subsurface properties, suggesting soil redox microheterogeneity that controls carbon transformation may be predictable over larger scales. Using the hillslope-to-floodplain gradient, I propose to evaluate the relationship between landscape features, PFT distribution, soil physical characteristics, and microbial metabolism, and then determine the consequences for soil carbon composition and storage. These relationships will inform a geospatial model utilizing LiDAR and hyperspectral data to predict anaerobic microsite formation and resulting carbon storage potential. Mentoring and teaching opportunities and the scope of this project will prepare Dr. Naughton for a faculty position in an undergraduate-oriented college where she intends to continue studying the influence of micro-scale soil heterogeneity on carbon cycling and the means to predict and represent this knowledge over larger spatial scales.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.