Doctoral Dissertation Research: Inter- and Intra-Storm Variability of Dissolved Organic Carbon and Nitrogen Fluxes from a Mid-Latitude Broadleaved Deciduous Forest Canopy

博士论文研究：中纬度阔叶落叶林冠层溶解有机碳和氮通量的风暴间和风暴内变化

• 批准号: 1003047
• 负责人: Delphis Levia
• 金额: $ 1.2万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1003047&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Inter; Intra

Mid-latitude, deciduous forests have become increasingly important global carbon (C) and nitrogen (N) sinks as human-related emissions from fuels, biomass burning, fertilizer use, and agricultural operations grow and tropical forests are harvested. Many studies have examined C and N storage within forested ecosystems, yet few have characterized the ecohydrological dynamics of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) derived from canopy sources. No known study has holistically examined the intra-storm variability of all canopy-derived DOC and DON fluxes for mid-latitude deciduous forests, although storm events being a critical period for the mobilization and transport of DOC and DON. Data quantifying the overall fate and transport of DOC and DON from canopy sources with respect to meteorological conditions and catchment characteristics are scant. To fill these data gaps, this doctoral dissertation research project will sample throughfall, stemflow, and litter leachate for two co-dominant tree species of contrasting canopy morphologies at the intra-storm scale and characterize the influence of meteorological conditions and catchment conditions on DOC and DON. Samples also will be analyzed for base cations for use in end-member mixing analyses (EMMA). EMMA will be used to evaluate hydrologic relationships between canopy-derived fluxes, variable source areas (VSA), and streamflow. Previous EMMAs have evaluated the influence of throughfall and litter leachate on streamflow chemistry and VSAs but neglected stemflow. The stemflow of many broadleaved deciduous trees gains preferential access to subsurface lateral flow. Hence, it is likely that the stemflow of certain species may contribute to streamflow and/or VSAs. This study will be the first to evaluate stemflow as an end-member in end-member mixing analysis and the first to monitor all canopy-derived DOC and DON fluxes for a single catchment at the intrastorm scale.Results will be used to review bulk sampling practices and assumptions made by current watershed models that generally disregard the influence of intrastorm variability and stemflow on the hydrology and water quality of forested catchments. If intrastorm variability or stemflow significantly contribute to the chemistry or hydrology of subsurface flux, VSAs, and/or streamflow for forested catchments, then widely-used models for civil engineering and environmental research and design that employ these assumptions will need to be corrected. Current bulk sampling practices also may need to be corrected if intrastorm variability significantly influences biogeochemical processes in forested catchments. Investigation of the intrasystem cycling dynamics of DOC and DON within mid-latitude deciduous forests during discrete storm events nonetheless will inform relevant theory in physical geography and hydrology that seeks to better understand the cycling of water and solutes in forests. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.

随着燃料，生物量燃烧，使用肥料的使用和农业作品的增长和热带森林的收获，随着人与人相关的排放，中纬度，落叶森林已变得越来越重要。 许多研究已经检查了森林生态系统中的C和N储存，但很少表征溶解的有机碳（DOC）和溶解的有机氮（DON）的生态水文动力学。 尽管风暴事件是动员和运输DOC和DON的关键时期，但尚无已知的研究整体研究所有树冠衍生的DOC和DON FLUXES在纬度落叶森林中的内在变异性。 量化DOC和DON在气象条件和集水特征方面的DOC和DON的总体命运和运输的数据很少。 为了填补这些数据差距，该博士学位论文研究项目将为两种依赖于对比的冠层形态的共同主导的树种对贯穿，茎流和垃圾渗漏进行采样，并表征气象条件和集水条件对DOC和DON的影响。 还将分析样品中的碱阳离子，以用于最终会员混合分析（EMMA）。 Emma将用于评估顶篷衍生的通量，可变源区域（VSA）和流量之间的水文关系。 以前的Emmas评估了遍布和垃圾渗漏对流量化学和VSA的影响，但被忽略了。 许多阔叶落叶树的茎流获得了对地下横向流的优先访问。 因此，某些物种的茎流很可能有助于水流和/或VSA。 This study will be the first to evaluate stemflow as an end-member in end-member mixing analysis and the first to monitor all canopy-derived DOC and DON fluxes for a single catchment at the intrastorm scale.Results will be used to review bulk sampling practices and assumptions made by current watershed models that generally disregard the influence of intrastorm variability and stemflow on the hydrology and water quality of forested catchments. 如果内部变异性或茎流显着有助于地下通量，VSA和/或流域的化学或水文学，则需要纠正使用这些假设的土木工程和环境研究和设计的广泛使用的模型。 如果内静脉变异性显着影响森林流域的生物地球化学过程，当前的批量抽样实践也可能需要纠正。 研究在离散风暴事件期间，对DOC和DON的内部循环动力学的研究将为物理地理和水文学中的相关理论提供信息，该理论旨在更好地了解森林中水和溶质的循环。 作为博士学位论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立强大的独立研究职业。