Soil Microbiomes Respond Predictably to Extreme Events
Extreme climatic events—such as droughts, floods, heatwaves, and freezing temperatures—are becoming more frequent due to climate change, posing significant challenges to terrestrial ecosystems. Soil microbiomes, composed of bacteria, fungi, and other microorganisms, play a vital role in regulating these ecosystems by driving essential biogeochemical processes, including carbon and nitrogen cycling. Understanding how soil microbiomes respond to extreme events is crucial for predicting ecosystem stability and resilience.
In their study, “Soil microbiomes show consistent and predictable responses to extreme events,” Christopher G. Knight and colleagues investigated how soil microbial communities from diverse European grasslands react to four types of climate disturbances. The researchers subjected soils from 30 different grassland sites to controlled drought, flooding, freezing, and heat conditions. Their findings reveal a surprisingly consistent microbial response, despite variations in soil composition and regional climate.
How Soil Microbiomes React to Climate Extremes
Rather than responding unpredictably, soil microbiomes exhibited a small but highly conserved shift in structure and function under extreme conditions. Heat exposure had the most pronounced effect, increasing the abundance of genes linked to dormancy and sporulation—mechanisms that microbes use to survive unfavorable conditions. Meanwhile, metabolic versatility, or the ability to use diverse energy sources, decreased following heat stress.
Other disturbances followed a pattern based on their effect on water availability:
Drought and Freezing triggered similar microbial shifts, likely because both reduce water availability. Drought-resistant microbes also exhibited resilience to freezing, suggesting that water limitation is a key driver of microbial adaptation.
Flooding produced the opposite effect, disrupting microbial communities by increasing water saturation and reducing oxygen availability.
Heatwaves caused the strongest disruption, favoring organisms capable of dormancy while reducing overall microbial diversity and functional capacity.
Local Climate Determines Microbiome Resilience
One of the study’s key insights is that a microbiome’s resilience depends on its native environment. Soils from regions that regularly experience drought, for example, showed greater resistance to drying conditions compared to those from wetter climates. This suggests that microbial communities in naturally extreme environments have already adapted to stressors, making them more resilient.
The researchers developed predictive models based on initial soil properties and local climate data to estimate how different microbiomes would respond to extreme events. Their results indicate that while soil communities across different regions share similar adaptation mechanisms, the magnitude of their response varies depending on prior exposure to similar stressors.
Implications for Climate Change and Soil Management
These findings provide valuable insights for predicting the effects of climate change on soil ecosystems. As extreme weather events become more frequent, regions unaccustomed to certain stressors—such as heatwaves in temperate zones—may experience greater microbial disruption. This, in turn, could affect soil fertility, greenhouse gas emissions, and overall ecosystem stability.
By identifying vulnerable areas, scientists and policymakers can focus conservation efforts where they are most needed. Additionally, strategies such as microbial inoculation—introducing resilient microbes to vulnerable soils—may help mitigate the impact of climate extremes on agricultural and natural ecosystems.
Understanding soil microbiomes’ predictable responses to environmental disturbances is a crucial step toward safeguarding soil health in a rapidly changing world.
References:
Knight, C.G., Nicolitch, O., Griffiths, R.I. et al. (2024). Soil microbiomes show consistent and predictable responses to extreme events. Nature 636, 690–696.