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

土壤二氧化碳外排是土壤碳通过植物和微生物呼吸作用释放到大气中的自然过程。虽然这一通量是森林生态系统中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。本论文试图在落基山脉北部的一个亚高山集水区确定这些生物物理控制与由此产生的通过土壤-大气界面的二氧化碳外流之间的关系。这项研究将通过实地观测(两个生长季节)获得的知识纳入到基于过程的建模方法中，以估计从点到集水尺度的土壤二氧化碳外流。实地知识将用于协助建模、参数化和校准。该模型可用于土壤和冠层碳通量的验证和整合。这项工作的协同性质将提供双向反馈，因为该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。这项研究涉及两个突出的生态水文学和碳循环研究问题：水文学作为土壤二氧化碳排放的时空控制的作用，以及年水文变化在调节生态系统碳平衡中的作用。这项研究的更广泛的影响包括本科生助理和学者的参与，将这项研究的数据纳入本科生流域科学课程的实地考察材料和家庭作业问题，以及少数民族学生(西班牙裔)接触研究。

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.