Calcium isotopic response to disturbance at Hubbard Brook: acidification, deforestation, and recovery

哈伯德布鲁克干扰的钙同位素反应：酸化、森林砍伐和恢复

• 批准号: 1324911
• 负责人: Andrew Kurtz
• 金额: $ 17.3万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1324911&HistoricalAwards=false
• 关键词: Calcium; isotopic; response; disturbance; Hubbard

This study evaluates changes in Calcium (Ca) cycling at the Hubbard Brook Experimental Forest in New Hampshire based on measurements of Ca stable isotope ratios on a unique sample archive dating to as early as 1963. Like other Northeast U.S. forests, the Ca cycle was significantly perturbed by acid deposition beginning in the early 1950's resulting in increased Ca loss from bio-available soil pools and detrimental effects on forest growth. Additionally, several of the first order watersheds at HBEF have been experimentally logged allowing examination of the relationship between harvesting, Ca cycling and forest ecology. Research will address the following questions: How do the Ca isotope ratios of streamwater and soil change in response to disturbances including acidification and deforestation? What can such data tell us about the mechanisms of Ca loss from forest ecosystems and changes in Ca cycling resulting from disturbance? An isotope-tracer box model indicates that soil and streamwater Ca isotopes reflect the relative magnitudes of important fluxes in the forest Ca cycle (external supply, plant uptake, and recycling to soil), leading to a series of testable hypotheses related to the ecosystem-level response to these perturbations. The main hypothesis is that forest growth will take up Ca, limiting it's input to streamwater, while deforestation will increase streamwater Ca as runoff from soil. To address questions and hypotheses, Ca isotope ratios and elemental concentrations will be determined on a carefully selected group of archived soil parent material, precipitation, streamwater, soil, and vegetation samples.Ca biogeochemistry has important implications for forest sustainability, both in the NE US, Northern Europe, and China. Ca isotopes, like other tracers of Ca cycling, has the potential to resolve some of the uncertainties in the sources of Ca loss from forests that are not apparent from mass balance studies alone. This information is important beyond biogeochemical research, with implications for forest management and regionally important agribusiness, such as maple syrup production. This project will primarily support a graduate student in Boston University's new Terrestrial Biogeosciences PhD program. The graduate student and the PI will create modules for use by a future year's cohort of GLACIER graduate students that introduce middle school students to New England biogeochemistry, acid rain, and forest sustainability. The results of this project will further be communicated to the about 300 students at Boston University and Tufts that the PI teaches annually.

这项研究评估了钙（Ca）循环的变化在哈伯德布鲁克实验森林在新罕布什尔州的基础上测量钙稳定同位素比的一个独特的样品档案追溯到早在1963年。与美国东北部其他森林一样，钙循环在20世纪50年代初开始受到酸沉降的显著干扰，导致生物有效土壤池中钙流失增加，对森林生长产生不利影响。此外，在HBEF的几个一阶流域已被实验记录允许检查之间的关系收获，钙循环和森林生态。 研究将解决以下问题：如何做的钙同位素比值的溪流和土壤的变化，以应对干扰，包括酸化和森林砍伐？这些数据可以告诉我们什么样的机制，从森林生态系统中的钙流失和钙循环的变化所造成的干扰？一个同位素示踪箱模型表明，土壤和河水钙同位素反映了森林钙循环（外部供应，植物吸收，并回收到土壤）的重要通量的相对大小，导致一系列可检验的假设相关的生态系统水平响应这些扰动。 主要的假设是，森林生长将采取钙，限制它的输入到流水，而森林砍伐将增加径流钙从土壤。 为了解决问题和假设，钙同位素比值和元素浓度将确定一组精心挑选的存档土壤母质，降水，流水，土壤和植被samples.Ca的地球化学森林可持续性，无论是在美国东北部，北方和中国具有重要意义。钙同位素，像其他示踪剂的钙循环，有可能解决一些不确定性来源的钙损失的森林，是不明显的质量平衡研究。这一信息的重要性超出了地球化学研究，对森林管理和区域重要的农业综合企业（如枫糖浆生产）具有影响。 该项目将主要支持波士顿大学新的陆地生物地球科学博士课程的研究生。研究生和PI将创建模块，供未来一年的GLACIER研究生使用，向中学生介绍新英格兰土壤地球化学、酸雨和森林可持续性。该项目的结果将进一步传达给波士顿大学和塔夫茨大学的约300名学生，PI每年授课。