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Phosphorus and base cations drive contrasting root dynamics in a central Amazon forest.
Jéssica Schmeisk-Rosa1, Kelly M Andersen2,3, Amanda L Cordeiro4
1Coordination of Environmental Dynamics, National Institute for Amazonian Research, Manaus, Brazil.
Plant and Soil
|April 3, 2026
Summary
Nutrient addition in Amazonian soils did not change fine root stocks but altered turnover rates. Phosphorus increased root turnover, while base cations decreased it, revealing distinct belowground plant strategies.
Area of Science:
- Tropical Ecology
- Soil Science
- Plant Physiology
Background:
- Amazonian soils are nutrient-poor, particularly in phosphorus (P) and base cations.
- Nutrient availability significantly impacts above- and belowground productivity (NPP).
- Understanding fine root dynamics is crucial for ecosystem function in low-fertility environments.
Purpose of the Study:
- To investigate the effects of P, base cations, and nitrogen (N) addition on fine root stocks and turnover.
- To determine how nutrient limitation influences belowground plant responses in central Amazonia.
- To test the hypothesis that P and base cations have stronger effects than N on fine root dynamics.
Main Methods:
- Sampling of fine roots (<2 mm diameter) from the 0-30 cm soil layer over two years.
- Utilizing a large-scale factorial experiment with P, base cation, and N additions.
- Calculating fine root turnover using in-growth cores to measure productivity and standing stock.
Main Results:
- Fine root stocks remained unaffected by any nutrient addition.
- Phosphorus addition significantly increased fine root turnover by 23% (Year 1) and 48% (Year 2).
- Base cation addition decreased fine root turnover by 24% in Year 2; N showed no significant effect.
Conclusions:
- Soil nutrient availability, especially P and base cations, regulates fine root standing stock and turnover in the central Amazon.
- Contrasting root responses indicate distinct belowground resource-use strategies influenced by nutrient mobility and plant physiology.
- Fine root dynamics are sensitive to nutrient inputs in low-fertility tropical ecosystems.
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