Environmental tipping points for global soil carbon fixation microorganisms

Area of Science:

• Soil Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Carbon fixation microorganisms (CFMs) are vital to the soil carbon cycle.
• Global distribution and environmental tipping points for CFMs are not well understood.
• Understanding CFM dynamics is crucial for soil health and climate change mitigation.

Purpose of the Study:

• To map the global distribution of carbon fixation microorganisms (CFMs).
• To identify environmental tipping points affecting CFM abundance.
• To predict future changes in CFM populations, particularly in croplands.

Main Methods:

• Utilized machine learning models to analyze factors influencing CFM abundance.
• Identified dominant roles of total carbon content, nitrogen fertilizer, and precipitation.
• Determined specific tipping points for these environmental variables.

Main Results:

• Total carbon content and precipitation showed significant stimulation/inhibition effects at low levels (tipping points: 6.1 g·kg⁻¹ and 22.38 mm, respectively).
• Nitrogen fertilizer exhibited a shift from positive to negative effects on CFM abundance (tipping point: 9.45 kg ha⁻¹·y⁻¹).
• Projected a 46% decline in CFM abundance in croplands by the year 2100.

Conclusions:

• Provides a global distribution map of CFMs, highlighting sensitive areas.
• Identified critical environmental thresholds for CFM abundance.
• Offers valuable data for future soil quality prediction and policy-making.