Dissertation Research: Hydrologic-carbon cycle linkages in a sub-alpine catchment

土壤二氧化碳排放是土壤碳通过植物和微生物呼吸作用释放到大气中的一个自然过程。 虽然这种通量代表了森林生态系统最大的自然呼吸通量，但土壤温度、土壤水分含量、土壤养分状况和植被覆盖对土壤二氧化碳排放的影响仍然知之甚少。 本论文的研究旨在确定这些生物物理控制和由此产生的二氧化碳排放量之间的关系，在亚高山流域的北方落基山脉的土壤-大气界面。 本研究将通过实地观测（两个生长季节）获得的知识纳入基于过程的建模方法，以估计点到集水区尺度的土壤二氧化碳排放量。 现场知识将用于辅助建模、参数化和校准。 该模型将有助于土壤和冠层水平碳通量的确证和整合。 这项工作的协同性质将提供双向反馈，因为模型将受益于实地知识，并可根据建模结果进一步探索经验数据。 本研究解决了两个突出的生态水文，碳循环研究问题：水文的作用，作为一个空间和时间的控制土壤二氧化碳排放，以及每年的水文变化在调节生态系统碳平衡的影响。 这项研究的更广泛的影响，包括本科助理和学者的参与，从这项研究的数据纳入实地考察材料和家庭作业的问题，本科流域科学类，少数民族学生（西班牙裔）的研究。

Soil carbon dioxide efflux is a natural process by which soil carbon is released into the atmosphere through plant and microbial respiration. While this flux represents the largest natural respiratory flux from forested ecosystems, the effects of soil temperature, soil water content, soil nutrient status, and vegetation cover on soil carbon dioxide efflux remain poorly understood. This dissertation research seeks to identify the relationship between these biophysical controls and the resultant carbon dioxide efflux across the soil-atmosphere interface in a subalpine catchment of the northern Rocky Mountains. This study incorporates knowledge gained through field observations (two growing seasons) into a process-based modeling approach to estimate point-to-catchment scale soil carbon dioxide efflux. Field knowledge will be used to aid in modeling parameterization and calibration. This model will be useful for corroboration and integration of soil and canopy level carbon fluxes. The synergistic nature of this exercise will provide bidirectional feedback, as the model will benefit from field knowledge, and empirical data can be further explored according to modeling results. This study addresses two outstanding eco-hydrological, carbon cycle research questions: the role of hydrology as a spatial and temporal control of soil carbon dioxide efflux, and the effects of yearly hydrological variability in regulating ecosystem carbon balance. The broader impacts of this research include involvement of undergraduate assistants and scholars, incorporation of data from this research into field trip materials and homework problems of undergraduate watershed science classes, and exposure of minority students (Hispanic) to research.