Below-ground carbon input to soil is controlled by nutrient availability and fine root dynamics in loblolly pine
John S King1, Timothy J Albaugh2, H Lee Allen2
1School of Forestry and Wood Products, Michigan Technological University, Houghton, MI 49931, USA.
The New Phytologist
|April 20, 2021
Summary
Fertilization boosts fine root production and turnover in loblolly pine (Pinus taeda) plantations, potentially increasing soil carbon input. Mycorrhizal root lifespan significantly influences this carbon exchange.
Area of Science:
- Forestry
- Soil Science
- Ecosystem Ecology
Background:
- Resource availability influences forest root dynamics and carbon cycling.
- Understanding root responses to environmental changes is crucial for predicting ecosystem function.
Purpose of the Study:
- To investigate how fertilization and irrigation affect root production, turnover, and lifespan in loblolly pine (Pinus taeda).
- To compare root dynamics with stem growth and foliage development under altered resource availability.
Main Methods:
- Factorial experiment with fertilization and irrigation treatments in a loblolly pine plantation.
- Minirhizotron observations over 3 years to assess fine, coarse, and mycorrhizal root production and turnover.
- Comparison of root dynamics with stem growth and foliage development.
Main Results:
- Fertilization significantly increased net production of fine and mycorrhizal roots, but not coarse roots.
- Average lifespans: fine roots (166 days), coarse roots (294 days), mycorrhizal roots (507 days).
- Fine roots exhibited multiple growth flushes, contrasting with seasonal foliage growth patterns.
Conclusions:
- Increased nutrient availability may enhance soil carbon input via increased fine root turnover.
- The impact on soil carbon depends on mycorrhizal root formation, given their longer lifespans.
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