Interactions between soil and tree roots accelerate long-term soil carbon decomposition.

Area of Science:

• Soil Science
• Ecology
• Biogeochemistry

Background:

• Soil organic carbon (SOC) decomposition releases CO2, impacting atmospheric carbon levels.
• The long-term effects of soil-root interactions on SOC decomposition are not well understood.

Purpose of the Study:

• To investigate the long-term impact of tree roots on SOC decomposition.
• To provide experimental evidence for the rhizosphere priming effect.

Main Methods:

• A 395-day greenhouse study.
• Ponderosa pine and Fremont cottonwood trees grown in three different soils.
• Comparison of SOC decomposition in planted treatments versus soil incubations alone.

Main Results:

• SOC decomposition was significantly higher (up to 225%) in planted treatments compared to unplanted controls.
• The rhizosphere priming effect persisted throughout the experiment.
• The effect increased with greater root-derived carbon input.

Conclusions:

• Tree roots substantially accelerate SOC decomposition via the rhizosphere priming effect.
• Increased carbon inputs from roots may lead to a net loss of soil carbon.
• This highlights the critical role of plant-soil interactions in carbon cycling.