Elevated ozone decreases the multifunctionality of belowground ecosystems.

Area of Science:

• Ecology
• Environmental Science
• Plant Science

Background:

• Tropospheric ozone (O3) is a significant air pollutant impacting terrestrial ecosystems.
• Ozone's effects on aboveground biomass and ecosystem functions are known, but belowground responses remain less understood globally.

Approach:

• A meta-analysis synthesized 2395 paired observations from 222 publications.
• Examined the effects of elevated O3 concentrations ([O3]) on root productivity, root/shoot ratio, and soil carbon and nitrogen cycling.
• Assessed alterations in microbial communities and ecosystem multifunctionality.

Key Points:

• Elevated O3 significantly reduced root primary productivity across crops, trees, and grasses (19.8%, 16.3%, 26.9% respectively).
• Root/shoot ratio decreased, indicating high root sensitivity to O3.
• O3 negatively impacted soil carbon and nitrogen cycling, decreasing microbial biomass and altering nutrient transformations in croplands.
• Fungal phospholipid fatty acids decreased, suggesting O3-induced changes in soil microbial community structure.

Conclusions:

• Elevated [O3] poses a significant threat to belowground ecosystem functions and overall multifunctionality.
• Experimental methods, root environments, and other global change factors modulate O3 impacts and must be considered in assessments.