Elevated CO₂ and Warming Altered Grassland Microbial Communities in Soil Top-Layers

Area of Science:

• Soil microbiology and biogeochemistry
• Climate change ecology
• Semiarid grassland ecosystems

Background:

• Rising atmospheric CO2 concentrations and global temperatures significantly impact terrestrial ecosystems.
• Soil microbial communities are crucial regulators of biogeochemical processes and respond dynamically to environmental shifts.
• The effects of combined elevated CO2 (eCO2) and warming on soil microbes in semiarid regions remain under-explored.

Purpose of the Study:

• To investigate the impact of warming, eCO2, and their interaction on the functional gene composition and metabolic potential of soil microbial communities.
• To understand how these climate change factors influence key soil biogeochemical processes, including carbon and nitrogen cycling.

Main Methods:

• Utilized a functional gene array (GeoChip 3.0) to analyze soil microbial communities.
• Experimentally applied warming, eCO2, and combined eCO2 + warming treatments in a semiarid grassland setting.
• Employed canonical correspondence analysis and Mantel tests to identify correlations between environmental factors and microbial gene variations.

Main Results:

• Both eCO2 and warming significantly altered soil microbial community composition and structure.
• eCO2 alone or with warming stimulated genes involved in carbon degradation/fixation and nitrogen cycling (fixation, mineralization).
• Warming alone inhibited genes related to denitrification and ammonification; interaction effects largely mirrored eCO2 effects.

Conclusions:

• Soil microbial communities exhibit distinct responses to individual and combined climate change factors.
• Warming may suppress nitrogen cycling, while eCO2 enhances both carbon and nitrogen cycling, potentially altering ecosystem feedback.
• Findings provide insights into semiarid grassland ecosystem responses to integrated global climate change drivers.