Fine-root mortality rates in a temperate forest: estimates using radiocarbon data and numerical modeling

Area of Science:

• Ecology
• Forest Science
• Biogeochemistry

Background:

• Fine-root dynamics are crucial for ecosystem carbon cycling.
• Existing models often oversimplify root turnover and carbon flow.
• Understanding root lifespan is key to accurate ecosystem process modeling.

Purpose of the Study:

• To develop and apply a novel model (Radix1.0) for simulating fine-root dynamics.
• To estimate turnover times for live and dead fine-root pools.
• To incorporate respiration, storage, and seasonal patterns into root dynamics modeling.

Main Methods:

• Utilized an inadvertent whole-ecosystem 14C label at a temperate forest.
• Developed the Radix1.0 model simulating multiple live/dead root pools and carbon storage.
• Applied the model to fine roots across different size classes and soil depths.

Main Results:

• Predicted live-root turnover times of <1 year and ~10 years.
• Estimated dead-root decomposition turnover times of ~2 years and ~10 years.
• Highlighted the necessity of multiple live/dead pools and respiration for accurate carbon flow.

Conclusions:

• Fine-root systems comprise distinct short- and long-lived populations with decadal turnover times.
• Current models may underestimate belowground net primary production due to simplified turnover assumptions.
• Accurate fine-root modeling requires accounting for complex dynamics like respiration and storage.