Doctoral Dissertation Research: Synoptic Climatological Approaches to Assessing Subcanopy Hydrologic and Nutrient Fluxes in a Temperate Deciduous Forest

博士论文研究：评估温带落叶林亚冠水文和养分通量的天气气候学方法

• 批准号: 1233592
• 负责人: Delphis Levia
• 金额: $ 1.38万
• 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: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1233592&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Synoptic; Climatological

This doctoral dissertation research project will focus on the flow of water and chemicals through forest canopies under different precipitation regimes. Deciduous temperate forests comprise over 280 million hectares in North and Central America and provide vital ecosystem services through the cycling of water and nutrients. During storm events, water moves through the forest canopy and exchanges nutrients and pollutants with vegetation and deposits the chemically altered precipitation to the forest floor. Both storm characteristics, such as intensity, duration, and magnitude, and the structural parameters of forest canopies have a significant control on the quantity and quality of such water, but how these may be influenced by altered precipitation regimes as a result of changing climates is largely uncertain. This project will yield a better understanding of the cycling of nutrients and pollutants within a forest canopy through hydrologic pathways that are ultimately controlled by atmospheric circulation and precipitation patterns at a field site in the Mid-Atlantic region. The doctoral student will link synoptic climatology with water and solute flux in temperate forests. Meteorological characteristics will be monitored at 5-minute intervals. These real-time ground observations will complement a long-term synoptic calendar, which will be developed to categorize common weather patterns experienced in the region. The partitioning of precipitation into throughfall (water intercepted by the canopy that continues to fall to the forest floor) and stemflow (water that is intercepted by the canopy and funneled down the tree trunk and deposited directly to the base of the tree) will be measured by automated tipping buckets at 5-minute intervals during storm events for two tree species of varying bark thickness and canopy geometry in order to understand the varying responses of precipitation in a heterogeneous forest canopy. Precipitation, throughfall, and stemflow samples will be collected after storm events and analyzed for important nutrients, such as dissolved organic carbon, calcium, magnesium, potassium, and sodium, and for anions, such as nitrates and sulfates, which can form acid rain. This project will provide new methodologies for estimating hydrologic and nutrient fluxes in forest canopies by integrating techniques of synoptic climatology and weather pattern analysis. This study will demonstrate how synoptic analysis of large-scale atmospheric circulation patterns may be used to estimate surface environmental conditions, thus reducing the demand for costly, fine-scale field observations. The dataset compiled in this study will be used to reconstruct a historical nutrient budget of Mid-Atlantic forests of similar composition and potentially forecast changes in forest hydrologic and nutrient budgets as a result of climate-induced changes to precipitation regimes. A more thorough understanding of the movement of water, nutrients, and pollutants in forest ecosystems will improve management capabilities and climate change mitigation efforts. 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.

该博士论文研究项目将重点研究不同降水情况下水和化学物质通过森林冠层的流动。 北美洲和中美洲的温带落叶森林面积超过 2.8 亿公顷，通过水和养分循环提供重要的生态系统服务。 在风暴事件期间，水穿过森林冠层，与植被交换养分和污染物，并将化学改变的降水沉积到森林地面。 强度、持续时间和震级等风暴特征以及森林冠层的结构参数对此类水的数量和质量具有显着的控制作用，但这些水量和质量如何受到气候变化导致的降水状况改变的影响尚不清楚。很大程度上不确定。 该项目将更好地了解森林冠层内养分和污染物通过水文路径的循环，这些路径最终由大西洋中部地区实地的大气环流和降水模式控制。 博士生将把天气气候学与温带森林的水和溶质通量联系起来。 每隔 5 分钟就会监测一次气象特征。 这些实时地面观测将补充长期天气日历，该日历将被开发用于对该地区经历的常见天气模式进行分类。 将测量降水分为径流（被树冠拦截的水，继续落到森林地面）和茎流（被树冠拦截的水，沿着树干流下，直接沉积到树的根部）在风暴事件期间，每隔 5 分钟自动翻斗一次，对两种树皮厚度和树冠几何形状不同的树种进行分析，以了解异质森林树冠中降水的不同响应。 风暴事件后将收集降水、径流和茎流样本，并分析重要的营养物质，如溶解的有机碳、钙、镁、钾和钠，以及可形成酸雨的阴离子，如硝酸盐和硫酸盐。该项目将通过整合天气气候学和天气模式分析技术，为估计森林冠层水文和养分通量提供新的方法。 这项研究将展示如何利用大规模大气环流模式的天气分析来估计地表环境条件，从而减少对昂贵的精细现场观测的需求。 本研究中编制的数据集将用于重建具有相似成分的中大西洋森林的历史养分预算，并可能预测由于气候引起的降水状况变化而导致的森林水文和养分预算的变化。 更全面地了解森林生态系统中水、养分和污染物的运动将提高管理能力和减缓气候变化的努力。 作为博士论文研究改进奖，该奖项还将为有前途的学生建立强大的独立研究生涯提供支持。