| 项目编号: | 1701092
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| 项目名称: | Dissertation Research: Interactions of pH on molybdenum and phosphorus limitation of nitrogen fixation in the Amazon Basin |
| 作者: | Robert Howarth
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| 承担单位: | Cornell University
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| 批准年: | 2017
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| 开始日期: | 2017-07-01
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| 结束日期: | 2019-06-30
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| 资助金额: | 20280
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Biological Sciences - Environmental Biology
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| 英文关键词: | nitrogen fixation
; molybdenum
; phosphorus
; amazon basin
; tropical forest
; southeastern amazon
; researcher
; soil
; access molybdenum
; low atmospheric input
; ph effect
; doctoral dissertation improvement grant
; molybdenum complexation
; phosphorus concentration
; nitrogen-fixing microorganism
; low phosphorus
; phosphorus availability
|
| 英文摘要: | Tropical forests are highly productive ecosystems and represent one-third of terrestrial primary production, but require nitrogen to support plant growth. Nitrogen fixation is a process carried out by microorganisms that allows tropical forests to replenish this nutrient. The highest documented nitrogen fixation rates are found in tropical forests, but few measurements have been made in the Amazon Basin, home to the world's largest tropical forest. Phosphorus and molybdenum are two elements that play an important role in the nitrogen fixation process. Indeed, phosphorus availability is known to limit nitrogen fixation, but no one has determined whether molybdenum has a similar effect in nature. Because molybdenum is rare, and is easily leached from soils, it's low concentration could lead to low nitrogen fixation rates in the Amazon Basin, where soils are nutrient depleted, and where regions receive little to no new inputs of molybdenum. These so-called "weathered" soils in the Amazon Basin are also acidic, and this condition can make it even more difficult for nitrogen-fixing microorganisms to access molybdenum. Research for this Doctoral Dissertation Improvement Grant will investigate how these factors interact to constrain nitrogen fixation, which affects how tropical forests will grow in response to environmental change.
The southeastern Amazon is an understudied but important forest ecosystem where (1) nitrogen fixation has not yet been quantified and (2) where molybdenum and phosphorus concentrations are low, likely due to low atmospheric inputs of these elements. Funds from this award will support experiments to test whether nitrogen fixation by free-living soil microorganisms in the southeastern Amazon is directly constrained by low phosphorus or molybdenum, or indirectly limited via pH effects on phosphorus and molybdenum complexation in soils. The researchers will conduct phosphorus, molybdenum, and lime plot addition experiments, and will measure long-term changes in nitrogen fixation rates and in the availability of phosphorus and molybdenum. Results will be disseminated in review papers for extrapolation of global nitrogen fixation rates for earth system models. In addition, the researchers will train and collaborate with Brazilian students and use the results to develop a teaching module for the annual Expanding Your Horizons workshop for middle school girls interested in science. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/89895
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Robert Howarth. Dissertation Research: Interactions of pH on molybdenum and phosphorus limitation of nitrogen fixation in the Amazon Basin. 2017-01-01.
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