Microbial Community Responses to Elevated Atmospheric CO2

Rising atmospheric CO2 concentrations are a defining feature of global change, with profound consequences for terrestrial ecosystems. Microbial communities in soil and the rhizosphere mediate biogeochemical cycles, influencing carbon sequestration, nutrient availability and plant productivity. Under elevated CO2, enhanced plant photosynthesis often increases carbon flux to roots, altering the quantity and composition of root exudates. These shifts can drive changes in microbial diversity, community composition and functional potential. Common responses include stimulation of genes involved in carbon degradation and fixation, nitrogen fixation and phosphorus mineralisation. However, the magnitude and direction of change depend on plant species, soil type, nutrient status and interacting factors such as ozone or warming. Across grasslands, agroecosystems and forests, elevated CO2 tends to favour fast-growing bacterial groups and symbiotic fungi, potentially accelerating nutrient turnover but also altering long-term soil carbon storage. Understanding these dynamics is key to predicting ecosystem feedbacks to climate change and to developing sustainable land-management strategies that harness beneficial plant–microbe interactions.

Research from Nature Portfolio

Studies on crop systems have revealed that plant species and genotype critically shape belowground microbiomes under elevated CO2. In a dual-crop experiment, soybean and maize grown under enhanced CO2 and ozone showed divergent responses: the soybean rhizosphere exhibited increased abundance of nitrogen-fixing bacteria, whereas maize communities were more strongly influenced by host genotype and root exudate profiles. Elevated ozone had little effect on rhizosphere composition but did alter soil communities in certain maize hybrids, highlighting the interplay between atmospheric factors and plant traits. In long-term field trials with a C4 maize agroecosystem exposed to elevated CO2 for eight years, functional gene arrays demonstrated upregulation of genes governing carbon, nitrogen and phosphorus cycling at both shallow and deeper soil layers. Carbon availability emerged as the dominant driver of shifts in functional gene structure, suggesting persistent impacts on ecosystem nutrient flows under future CO2 scenarios.

Microbial Community Responses to Elevated Atmospheric CO2 publication trend

The graph below shows the total number of articles in microbial community responses to elevated atmospheric co2 across all publications each year (not limited to Nature Index journals).

Technical terms

Rhizosphere: The narrow zone of soil influenced by root secretions and associated microbial activity.

Alpha diversity: A measure of species richness and evenness within a single community sample.

Functional gene array: A high-throughput tool for detecting and quantifying genes responsible for specific metabolic processes in environmental samples.

Root exudates: A complex mixture of organic compounds released by plant roots that serve as substrates or signals for soil microbes.

References

1. Shifts in microbial communities in soil, rhizosphere and roots of two major crop systems under elevated CO2 and O3. Scientific Reports (2017).
2. Elevated CO2 shifts the functional structure and metabolic potentials of soil microbial communities in a C4 agroecosystem. Scientific Reports (2015).
3. Elevated CO2 and nitrate levels increase wheat root-associated bacterial abundance and impact rhizosphere microbial community composition and function. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2020).
4. Elevated atmospheric CO2 alters the microbial community composition and metabolic potential to mineralize organic phosphorus in the rhizosphere of wheat. Microbiome (2022).