MSA: Self-organizing principles for upscaling ecosystem water and heterotrophic carbon fluxes

气候变化和土地管理正在影响全球土壤，对土壤健康和生物多样性、植物生产力和气候调节产生不利影响。然而，土壤有机碳的损失及其作为二氧化碳的排放仍然是最不确定的陆地碳通量之一，土壤有机碳是由土壤微生物调节的主要大气碳输入（称为异养呼吸）。本研究旨在通过结合来自多个观测网络的实验数据和微生物生长和代谢的数学模型，了解异养呼吸如何在生物群系和气候中根据宏观环境变量（例如，降雨和植被生产力）以及从生态系统到大陆尺度发生变化。这种分析有助于绘制区域到大陆尺度的异养呼吸图，并通过更准确地估计土壤有机碳损失来评估气候变化对土壤和生态系统的潜在影响。这项工作使致力于生态系统管理和可持续性的环境政策制定者能够规划有效的保护战略，特别是针对那些对气候变化最敏感的地区。该项目将培养多样化的学生，并将支持微生物学、水文学、环境科学与工程交叉学科的新跨学科课程材料的开发。本研究基于以下假设：在生态系统尺度上，年异养呼吸与植物生产力之比（一种与土壤碳预算相关的无量纲测量）主要与干旱指数（一种无量纲的湿/干测量）相关。该项目结合了基于过程的微生物生长模型与通量塔数据集，以及来自NEON和其他区域和全球网络的基于现场的土壤和生态系统碳通量测量，以量纲分析的π定理为指导，探索解释生物群落间水和碳通量变化的基本规律的存在。一个基于简约过程的微生物模型被用于分析观测结果，并将微生物参数与宏观环境驱动因素统计联系起来，并确定控制大尺度动力学的关键无量纲群。然后利用异养呼吸与环境驱动因素之间的宏观关系，基于主要环境驱动因素的空间结构重构大尺度碳通量。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。

Climate change and land management are affecting soils globally, with detrimental consequences for soil health and biodiversity, plant productivity, and climate regulation. However, the loss of soil organic carbon and its emission as carbon dioxide, which is a major input of carbon to the atmosphere regulated by soil microorganisms (known as heterotrophic respiration), remains one of the most uncertain terrestrial carbon fluxes. This research aims to understand how heterotrophic respiration varies across biomes and climates depending on macroscopic environmental variables (for example, rainfall and vegetation productivity) and from the ecosystem to continental scale, by combining experimental data from multiple observational networks and mathematical models of microbial growth and metabolism. This analysis is helping to map heterotrophic respiration at regional to continental scales and assess the potential impact of climate change on soils and ecosystems by enabling more accurate estimates of soil organic carbon losses. The effort allows environmental policymakers working on ecosystem management and sustainability to plan effective conservation strategies, especially for those regions that are most sensitive to climate change. The project will train diverse students and will support the development of new interdisciplinary curricular material at the intersection of microbiology, hydrology, and environmental science and engineering.This research is guided by the hypothesis that at the ecosystem scale the ratio of annual heterotrophic respiration to plant productivity (a dimensionless measure related to the soil carbon budget) is primarily correlated with the aridity index (a dimensionless measure of wetness/dryness). The project combines process-based microbial growth modeling with flux tower datasets and field-based measurements of soil and ecosystem carbon fluxes from NEON and other regional and global networks to explore, guided by the π theorem of dimensional analysis, the existence of fundamental laws explaining the variability in water and carbon fluxes across biomes. A parsimonious process-based microbial model is being used to analyze observations and statistically link microbial parameters to macroscopic environmental drivers and identify key dimensionless groups governing the large-scale dynamics. The macroscopic relations between heterotrophic respiration and environmental drivers are then used to reconstruct large-scale carbon fluxes based on the spatial structure of primary environmental drivers.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.