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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

The Role of Aluminum and Organic Acids in the Regulation of Tropical Forest Nutrient Cycles

EPA Grant Number: U915956
Title: The Role of Aluminum and Organic Acids in the Regulation of Tropical Forest Nutrient Cycles
Investigators: Barron, Alexander R.
Institution: Princeton University
EPA Project Officer: Boddie, Georgette
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $102,000
RFA: STAR Graduate Fellowships (2001)
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration



The objective of this research project is to survey nondulation and fixation rates for three common tree genera (Tachigalia, Platypodium, and Inga) across three landscape types (old forest, young forest, and shoreline) in Barro Colorado National Monument, Panama.


Nitrogen (N)-fixing plants, with the capacity to transform atmospheric N2 into a plant-available form (NH3), often are cited as a functional group with huge potential impacts on ecosystem N dynamics. Despite the abundance of potentially N-fixing legumes in lowland tropical forests, little is known about how much they rely on N fixation, how much N they contribute to the ecosystem, and what factors limit rates of fixation. Initial surveys indicate strong differences between sites, with high levels of nodulation in the young forest and shoreline, but no detectable nodules in the older forest. Simultaneously, levels of N, phosphorus, and micronutrients will be measured so that fixation rates can be correlated to soil nutrients and stoichiometry. Correlations from field surveys will be confirmed by examining patterns of nodulation in long-term nutrient addition plots. By linking fixation rates across multiple forest types to nutrient supplies, this research project will provide crucial information on the contribution of symbiotic N fixation to forest N cycles. Parallel studies will examine patterns and controls on nonleguminous fixation and the relationship between N fixation and other traits within the Leguminosae.

Supplemental Keywords:

fellowship, aluminum, organic acids, tropical forest, nutrient cycles, nitrogen-fixing plants, nitrogen fixation, Panama, atmospheric nitrogen.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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