Microbial functional genes commonly respond to elevated carbon dioxide.

Area of Science:

• Microbial Ecology
• Environmental Science
• Biogeochemistry

Background:

• Atmospheric CO₂ concentrations are rising due to human activities.
• Previous studies on elevated CO₂ (eCO₂) impacts on soil microbes lack consistent patterns.
• Predicting future ecosystem functions under eCO₂ remains challenging.

Purpose of the Study:

• To identify common microbial functional gene responses to eCO₂ across multiple Free-Air CO₂ Enrichment (FACE) sites.
• To link these gene responses to key ecosystem processes.
• To develop a framework for predicting ecosystem functioning and sustainability under future eCO₂ levels.

Main Methods:

• Analysis of 66 soil microbial communities from five FACE sites.
• Examination of key functional genes involved in carbon/nitrogen cycling and greenhouse gas emissions.
• Literature survey of additional FACE experimental sites.

Main Results:

• Common microbial response patterns to eCO₂ were identified, particularly for genes in carbon fixation (pcc/acc), nitrogen fixation (nifH), carbon decomposition (amyA, pulA, mnp, lcc), and greenhouse gas production (mcrA, norB).
• The abundance of these genes increased with eCO₂, correlating with higher biomass, soil carbon decomposition, and moisture.
• A literature survey confirmed increased biomass, carbon decomposition, nitrogen fixation, and greenhouse gas emissions under eCO₂.

Conclusions:

• Common responses of soil microbial functional genes to eCO₂ provide a basis for predicting ecosystem functioning.
• The identified gene-ecosystem process links (e.g., pcc/acc and carbon storage) offer insights into future environmental changes.
• These findings enhance our ability to forecast ecosystem sustainability in a high-CO₂ world.