Doctoral Dissertation Research: Multiproxy Analysis of Tropical Cyclones and Climate Variability at Big Thicket National Preserve, Texas

博士论文研究：德克萨斯州大丛林国家保护区热带气旋和气候变化的多代理分析

• 批准号: 0902503
• 负责人: David Finkelstein
• 金额: $ 0.83万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0902503&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Multiproxy; Analysis

Because trees are stationary organisms, they are dependent on their surrounding environment. Trees incorporate carbon from atmospheric carbon dioxide and oxygen from soil moisture into annual layers of wood (cellulose). When the annual rings are accurately dated using established dendrochronological techniques, high-resolution stable isotope chronologies can document environmental change. This doctoral dissertation research project will examine the relationships between tree-ring stable isotopes (carbon and oxygen) and tree-ring width with various climate properties, such as drought, temperature, precipitation, tropical cyclone events, and large-scale ocean/atmospheric oscillation patterns at Big Thicket National Preserve in Texas. Tree-ring climate records will be developed using small-diameter increment cores taken from living longleaf pine trees. The width and chemistry of each annual tree ring will be analyzed to provide a record of climate variability and tropical cyclone frequency and variability along the Texas Gulf Coast. Tropical cyclone (hurricane) systems can produce rainfall with a chemical signal distinct from that of normal rainfall. Rainfall from tropical cyclone events should replace or mix with existing soil waters and may remain in the soil for up to six weeks. Tree-ring cellulose therefore can be used to identify both modern and past hurricane events.Because hurricanes pose a threat to many people living along the Gulf and Atlantic coasts of the southeastern United States, the capability to build centuries-long hurricane records from biological and chemical records is crucial to enhance understanding about how these events have changed through recent times, as well as for understanding the possible changes that could occur in the future. One oxygen isotope study used to characterize tropical cyclone events and climate variability in the southeastern U.S. used only one tree for any portion of the isotope chronology, but such single-tree chronologies may be problematic for interpreting regional climate for several reasons. This research project will attempt to overcome these problems by addressing several possible limitations. First, the chemical (isotopic) composition of soil water being used by trees for photosynthesis may not be homogeneous across an entire stand. Second, the amount of chemically distinctive rainwater characteristic of tropical cyclone events may not uniformly replace the existing soil moisture evenly across a stand. Finally, a single tree may not be capable of capturing enough of the common climate signal to characterize the effects of regional climate. This project will test these possible limitations by analyzing single-tree isotope chronologies versus multiple-tree chronologies. The results should help characterizing the variability that exists in the isotopic composition of soil moisture in a stand. 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.

因为树木是静止的生物，它们依赖于周围的环境。 树木将大气中的二氧化碳和土壤水分中的氧气吸收到每年的木材层（纤维素）中。 当使用已建立的树木年代学技术准确测定年轮时，高分辨率的稳定同位素年代学可以记录环境变化。 这个博士论文研究项目将研究树轮稳定同位素（碳和氧）和树轮宽度与各种气候特性之间的关系，如干旱，温度，降水，热带气旋事件，以及德克萨斯州大灌木丛国家保护区的大规模海洋/大气振荡模式。 将使用取自活长叶松树的小直径生长芯来制作树木年轮气候记录。 将分析每棵树年轮的宽度和化学成分，以记录德克萨斯州墨西哥湾沿岸沿着的气候变化和热带气旋频率和变化。 热带气旋（飓风）系统可以产生具有不同于正常降雨的化学信号的降雨。 热带气旋事件产生的降雨应取代现有土壤沃茨或与之混合，并可能在土壤中停留长达六周。 因此，树木年轮纤维素可用于识别现代和过去的飓风事件。由于飓风对生活在美国东南部沿着的墨西哥湾和大西洋沿岸的许多人构成威胁，因此，从生物和化学记录中建立长达几个世纪的飓风记录的能力对于加强了解这些事件在近代是如何变化的至关重要，以及了解未来可能发生的变化。一项用于描述美国东南部热带气旋事件和气候变率的氧同位素研究仅使用一棵树作为同位素年表的任何部分，但由于多种原因，这种单树年表在解释区域气候时可能存在问题。 本研究项目将试图通过解决几个可能的限制来克服这些问题。 首先，化学树木用于光合作用的土壤水的（同位素）成分在整个林分中可能不是均匀的。第二，热带气旋事件特有的化学性质不同的雨水量可能不会均匀地取代整个林分中现有的土壤水分。最后，一棵树可能无法捕获足够的共同气候信号来表征区域气候的影响。 本项目将通过分析单树同位素年表与多树年表来测试这些可能的限制。 结果应该有助于表征土壤水分同位素组成中存在的变异性。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立一个强大的独立研究事业。