Collaborative Research: Organic Nitrogen Cycling in Northern Hardwood - Conifer Forests

合作研究：北部硬木-针叶林的有机氮循环

• 批准号: 0743348
• 负责人: Erik Hobbie
• 金额: $ 14.71万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0743348&HistoricalAwards=false
• 关键词: Collaborative; Research; Organic; Nitrogen; Cycling

The current conceptual model for the nitrogen (N) cycle of northeastern US forests stresses the importance of inorganic N forms (i.e., ammonium and nitrate) for tree growth and forest productivity. However, organic forms of N are also be taken up by plants. The overall objective of this proposal is to quantify the importance of organic N as a nutrient source in temperate forest ecosystems of the northeastern U.S. To achieve this objective, the factors that affect the production and turnover of organic N in the soil will be studied, focusing specifically on amino acids and amino sugars. The balance between the production and turnover of organic N will be assessed to determine the types and forms of N taken up by dominant tree species. These objectives will be met by establishing plants in single-species stands on two types of soil parent materials in western Connecticut and Massachusetts. Field and laboratory studies will be used to measure the pools, fluxes and uptake of organic N in the soil. The availability of N in the soil limits the productivity of forest ecosystems and their capacity to sequester rising concentrations of carbon dioxide, a greenhouse gas. By understanding the factors that affect the form and the quantity of N taken up by forest trees, this proposal will shed light on the processes regulating the availability of a key growth limiting soil resource and the degree to which forest ecosystems can be relied upon to absorb CO2 from the earth's atmosphere.

目前美国东北部森林氮(N)循环的概念模型强调无机氮形式（即铵和硝态氮）对树木生长和森林生产力的重要性。然而，有机形式的氮也被植物吸收。本提案的总体目标是量化有机氮在美国东北部温带森林生态系统中作为营养来源的重要性。为了实现这一目标，将研究影响土壤中有机氮生产和转化的因素，特别关注氨基酸和氨基糖。将评估有机氮的生产和周转之间的平衡，以确定优势树种吸收氮的类型和形式。这些目标将通过在康涅狄格州西部和马萨诸塞州的两种土壤母质上建立单一物种的植物来实现。实地和实验室研究将用于测量土壤中有机氮的库、通量和吸收。土壤中氮的可用性限制了森林生态系统的生产力及其吸收二氧化碳（一种温室气体）浓度上升的能力。通过了解影响森林树木吸收氮的形式和数量的因素，该提案将阐明调节关键生长限制土壤资源可用性的过程，以及森林生态系统可以依赖于从地球大气中吸收二氧化碳的程度。