14C-Age of Carbon Used to Grow Fine Roots Reflects Tree Carbon Status
Boaz Hilman1, Emily F Solly2,3, Frank Hagedorn4
1Max-Planck Institute for Biogeochemistry, Jena, Germany.
Plant, Cell & Environment
|September 5, 2025
Summary
Tree carbon allocation varies with elevation. Younger carbon in leaves and branches contrasts with older carbon in roots, showing environmental factors, not species, drive these dynamics.
Area of Science:
- Ecology
- Plant Physiology
- Biogeochemistry
Background:
- Nonstructural carbohydrates (NSC) are vital for tree growth.
- Carbon-14 (14C) dating estimates the time between NSC fixation and tissue growth.
- NSC age in root tissues varies significantly, from under a year to decades.
Purpose of the Study:
- To investigate the factors controlling the variability of NSC 14C-ages in tree tissues.
- To compare NSC 14C-ages in leaf, branch, and root tissues across different environmental conditions.
- To understand how environmental gradients influence carbon allocation in conifers.
Main Methods:
- 14C dating of leaf, branch, and root tissues from Larix decidua and Pinus mugo.
- Comparison between a valley site and an alpine treeline ecotone.
- Analysis of respiration rates and NSC concentrations along an elevation gradient.
Main Results:
- Respiration rate and NSC concentration increased with elevation.
- Younger NSC 14C-ages (< 2 years) were observed in leaf and branch tissues.
- Older NSC 14C-ages in roots increased from 2 to 10 years from the valley to the lower ecotone, then decreased to 6 years at the ecotone top.
- Environmental conditions, rather than species, were the primary drivers of carbon allocation.
Conclusions:
- Environmental conditions significantly influence carbon allocation dynamics in trees.
- Elevation gradients affect the age of NSC used for root growth.
- 14C-ages of fine roots reflect overarching environmental controls on carbon allocation.
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