The lung no more! 


Breaking down the microbiology world one bite at a time

The lung no more! 

Tropical forests are often called ‘the lungs of our planet’ because they take in a lot of carbon dioxide and release oxygen, which we need to breathe! When we think of tropical forests, we also think of the most diverse ecosystems on Earth with many plants and animals but we rarely think of all the microbes living in the soil of tropical forests. Yet, they not only contribute to sustaining the aboveground life (plants and animals) but they also participate in the uptake and release of carbon dioxide. Therefore, just as changes in plant communities (especially deforestation = cutting down trees) will impact the emission of carbon dioxide and oxygen to the atmosphere, changes in soil microbial diversity – due to climate warming – are predicted to increase the release of carbon dioxide to the atmosphere, worsening climate change and its impact on our planet! 

Yet, studies on the impact of global warming on tropical soil microbial communities are limited and this is where the study by Nottingham et al. comes into play. They conducted experiments to investigate the changes in soil microbial communities to determine if the communities can adapt to this warming and the consequences on carbon dioxide emissions. 

They went to a tropical forest in Panama and installed big heaters in the soil to warm the soil from 26°C (control, not warmed), to 29°C (+3°C) and 34°C (+8°C), in accordance with the warming predicted by the end of this century if nothing is done to limit climate change. Every week, they measured carbon dioxide emissions from the soil and collected samples to characterise the microbial communities. They found that after two years of warming, the microbial diversity was reduced and microbial communities changed to promote stress and heat-resistant bacteria and fungi. More worryingly, they found that carbon dioxide emissions increased by 78% with an increase of 3°C and 337% with an increase of 8°C! The authors investigated why carbon dioxide emissions increased so much with warming and showed that soil microorganisms like warm temperatures: they grow faster and their enzymatic activity increases.  

Summary of the experiment: the soil was warmed from 26°C (control) to 34°C. The authors measured CO2 emissions and characterised the microbial communities of the soil. They observed a strong increase in CO2 emissions linked to increased growth and enzymatic activity and a decrease in microbial diversity. 

These increases in carbon dioxide emissions with warming are alarming! It shows that even if the soil is a few degrees warmer, it has a major impact on tropical soil systems and carbon cycling. With more carbon dioxide released into the atmosphere, climate change will only worsen! More studies are urgently needed to investigate ways to mitigate the impact of warming on these soil communities. Especially since changes in soil communities are likely to have a major impact on aboveground communities as well such as plants or animals.  

Link to the original post: Nottingham, A. T., Scott, J. J., Saltonstall, K., Broders, K., Montero-Sanchez, M., Püspök, J., … & Meir, P. (2022). Microbial diversity declines in warmed tropical soil and respiration rise exceed predictions as communities adapt. Nature Microbiology, 7(10), 1650-1660.

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