Microbial temperature sensitivity and biomass change explain soil carbon loss with warming

Area of Science:

• Soil Science
• Microbial Ecology
• Climate Change Research

Background:

• Soil microorganisms play a crucial role in regulating atmospheric carbon.
• Their responses to climate warming are often transient and unpredictable.
• Existing theories of microbial acclimation or substrate depletion lack strong empirical support.

Purpose of the Study:

• To investigate the long-term effects of climate warming on soil microbial activity and carbon loss.
• To determine whether soil microbes acclimate to sustained warming.
• To elucidate the mechanisms driving temporary soil carbon loss under warming conditions.

Main Methods:

• Utilized a long-term geothermal field experiment with sustained warming (> 50 years).
• Conducted a short-term experiment to assess microbial responses.
• Measured gross rates of microbial growth, turnover, respiration, and carbon uptake.
• Employed a microbial biogeochemical model to simulate observed phenomena.

Main Results:

• Microbial activity demonstrated intrinsic temperature sensitivity and did not acclimate to +6 ºC warming over decades.
• Permanently accelerated microbial activity initially led to increased soil carbon loss.
• Soil carbon loss was temporary, as substrate depletion reduced microbial biomass and ecosystem influence.

Conclusions:

• Intrinsic microbial temperature sensitivity and substrate depletion are key drivers of warming-induced soil carbon loss.
• These factors collectively regulate microbial biomass, influencing ecosystem carbon dynamics.
• A framework is provided for understanding the relationship between temperature, microbial activity, and soil carbon loss over climate-relevant timescales.