Ecosystem CO₂ release driven by wind occurs in drylands at global scale

Area of Science:

• Earth and Environmental Sciences
• Ecology
• Atmospheric Science

Background:

• Subterranean ventilation is a non-diffusive CO2 transport from soil to atmosphere.
• Dryland ecosystems' carbon exchange is poorly understood, yet ventilation significantly influences CO2 fluxes.
• Previous research has overlooked the role of ventilation-driven CO2 emissions in land-atmosphere exchange.

Purpose of the Study:

• To provide empirical evidence of globally occurring subterranean ventilation episodes (VE).
• To investigate the role of VE CO2 emissions in land-atmosphere CO2 exchange, particularly in dryland ecosystems.
• To develop a standardized method for detecting VE-driven CO2 emissions.

Main Methods:

• Utilized quality-controlled eddy-covariance data from 145 global sites (FLUXNET2015, AmeriFlux, OzFlux, AsiaFlux).
• Developed and applied an algorithm to detect CO2 emissions correlated with high turbulence (friction velocity).
• Analyzed data from various land cover types including grassland, cropland, shrubland, savanna, and barren land.

Main Results:

• Subterranean ventilation episodes were detected at 34% of the analyzed sites globally.
• VE-driven CO2 emissions predominantly originated from arid ecosystems (84%) and sites experiencing hot, dry periods.
• The findings confirm the global occurrence of VE-driven CO2 emissions, despite data limitations.

Conclusions:

• Subterranean ventilation is a significant, globally occurring process impacting the carbon cycle.
• VE-driven CO2 emissions are particularly prevalent in arid and semi-arid regions.
• Further research is needed to understand VE drivers and improve carbon flux partitioning models for accurate ecosystem carbon balance assessment.