Ammonia-oxidizing bacteria respond to multifactorial global change

Area of Science:

• Microbial Ecology
• Global Change Biology
• Soil Science

Background:

• Global changes, including increased atmospheric CO2, precipitation, temperature, and nitrogen deposition, significantly impact plant communities.
• Soil microorganisms play a crucial role in mediating ecosystem responses to global change.
• Limited understanding exists regarding the effects of multiple global changes on microbial communities.

Purpose of the Study:

• To investigate the response of ammonia-oxidizing bacteria (AOB) communities to simultaneous global change factors.
• To determine how altered atmospheric CO2, precipitation, temperature, and nitrogen deposition affect AOB structure and abundance.
• To assess the implications of these changes for nitrification processes.

Main Methods:

• Ecosystem-level manipulation of atmospheric CO2, precipitation, temperature, and nitrogen deposition in a California grassland.
• Analysis of ammonia-oxidizing bacteria (AOB) community structure and abundance using molecular techniques.
• Measurement of nitrification rates to correlate with microbial community shifts.

Main Results:

• Nitrogen deposition significantly altered AOB community structure, favoring bacteria related to Nitrosospira sp. 2, especially without increased temperature and precipitation.
• Elevated atmospheric CO2 led to a significant decrease in total AOB abundance, most pronounced with increased precipitation.
• Shifts in AOB community composition correlated with increased nitrification, but changes in AOB abundance did not.

Conclusions:

• Microbial communities, specifically AOB, exhibit consistent responses to multiple global change drivers.
• These alterations in microbial communities have significant implications for critical ecosystem functions like nitrification.
• Understanding microbial responses is vital for predicting ecosystem behavior under future global change scenarios.