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Updated: Sep 2, 2025
10:49
Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading
Published on: March 6, 2014
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Direct evidence for phosphorus limitation on Amazon forest productivity
Hellen Fernanda Viana Cunha1, Kelly M Andersen2,3, Laynara Figueiredo Lugli4,5
1Coordination of Environmental Dynamics, National Institute for Amazonian Research, Manaus, Brazil. hfcunha.florestal@gmail.com.
Nature
|August 10, 2022
Summary
Phosphorus availability limits Amazon rainforest productivity, contrary to previous assumptions. Fertilization experiments show phosphorus addition significantly boosts canopy and root growth in these vital ecosystems.
Area of Science:
- Tropical ecology
- Soil science
- Biogeochemistry
Background:
- Rainforests on weathered soils are often phosphorus-limited.
- Previous fertilization studies yielded uncertain results on phosphorus's role.
- Amazonian soils are typically more phosphorus-depleted than experimental sites.
Purpose of the Study:
- To investigate phosphorus limitation in Amazonian rainforests.
- To determine the impact of nutrient addition on net primary productivity.
- To assess implications for carbon sequestration and climate change resilience.
Main Methods:
- Established a nutrient addition experiment (phosphorus, nitrogen, base cations) in an old-growth Amazonian rainforest.
- Utilized a site representative of 60% of the Amazon basin with low soil phosphorus.
- Monitored net primary productivity, including fine root and canopy growth, over two years.
Main Results:
- Net primary productivity increased exclusively with phosphorus addition.
- Fine root productivity increased by 29% and canopy productivity by 19% after two years.
- Stem growth showed no significant response to nutrient additions.
Conclusions:
- Phosphorus availability is a key limiting factor for net primary productivity in this Amazonian rainforest.
- This limitation may hinder forest responses to carbon dioxide fertilization.
- Findings have significant implications for future carbon sequestration and forest resilience.
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Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, such as phosphate ions (PO43-), found in soil, water, sediment and rocks. Phosphorus is often a limiting nutrient (i.e., in short supply). Consequently, phosphorus is added to most agricultural fertilizers, which can cause environmental problems related to runoff in aquatic ecosystems.
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01:06Primary Production
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