Accelerated terrestrial ecosystem carbon turnover and its drivers.

Area of Science:

• Earth System Science
• Ecology
• Climate Science

Background:

• The terrestrial carbon cycle is significantly impacted by anthropogenic CO2, climate change, and land use.
• Changes in vegetation productivity and ecosystem carbon turnover time (τeco) alter ecosystem carbon balance.
• Global changes in τeco remain poorly understood despite extensive research on vegetation productivity.

Purpose of the Study:

• To analyze changes in ecosystem carbon turnover time (τeco) from the 1860s to the 2000s.
• To identify the primary drivers of these τeco changes.
• To understand the implications for climate-carbon cycle feedbacks.

Main Methods:

• Utilized theory of dynamic carbon cycle in non-steady state.
• Employed process-based ecosystem models for analysis.
• Examined τeco changes at biome and grid scales.

Main Results:

• Ecosystem carbon turnover time (τeco) decreased by 13.5% between the 1860s (74 years) and 2000s (64 years).
• Carbon residence times reduced by 1 year in vegetation (rveg) and 9 years in soil (rsoil).
• Land use change and climate change were identified as the dominant drivers accelerating τeco.

Conclusions:

• Terrestrial ecosystems are experiencing accelerated carbon turnover, leading to faster carbon loss to the atmosphere.
• This acceleration has significant implications for understanding and predicting climate-carbon cycle feedbacks.
• The findings highlight the dynamic nature of the terrestrial carbon balance under anthropogenic pressures.