Breaking down the microbiology world one bite at a time
Are shorter winters helping microbes bloom?
Originally published in the The Microbial times
Did you know that over the past two decades, the air temperature of the Arctic surface has increased 2X (!) more than the global average? This affirms that the Arctic of the Northern pole is truly the most sensitive region to increasing temperature due to global warming. The impact of these drastic climate changes have indeed grabbed the attention of our planet and its inhabitants, including the ever-responsive microbial communities.
What’s going on in the Arctic tundra?
The serious phenomenon of Arctic amplification occurs when the Arctic warms much faster than the rest of the globe (4X more as of late!). As Climate Signals explains, as the temperature increases, this loss leads to changes and vulnerability in the ecosystem because organisms cannot always adapt so quickly.
Though more drastic in the Arctic, these changes even extend their influences at a global level, making the Arctic central in regulating temperatures worldwide. And within this vital Arctic, lies the tundra — a cold ecosystem that is mostly hostile and inhospitable throughout the year, with cold, windy and scanty rainfall. But, the tundra is also valuable. It contains the largest carbon stock (carbon stored from the atmosphere to the ecosystem) frozen within its permafrost.
However, in the past few years, this is no longer true.
With rising temperatures, these tundras have shifted from being a net carbon sink (capturing carbon) to a net carbon source (emitting carbon)! As the ice tapers and melts, and organic carbon within the permafrost thaws — thanks to rising temperature, it starts favoring life, starting with microbial growth and activities.
As microbes thrive, they engage in various interactions among themselves and the environment that include decomposition, nutrient cycling and carbon balance. As temperatures increase, so does the growing season duration. When microbes grow abundantly, they are involved in nutrient cycling, through which plants— especially woody shrubs — reap the maximum benefit. This further leads to high amounts of litter and with this, increased rates of decomposition, and the cycle goes on. As plants flourish in number, they start encroaching which turns into another issue. With the encroachment of plants and microbes, the former carbon storage steadily changes to a carbon sink in the long run; thereby altering the very nature of this ecosystem!
From outdoors to lab-doors, some key observations
In a recent study, using moist acidic tundra plots in plastic greenhouses to imitate the tundra setting, scientists observed bacterial growth by incorporating 18O in the soil — both long (29 years) and short (3 months) terms. They further noted the effects of increasing warmth (1.5 ℃) in the ecosystem and most importantly, the bacteria.
The scientists found that warming led to increased soil bulk-respiration, carbon and nitrogen cycling enzymes, and abundance of functional genes. They concluded that microbial activity had enhanced in the tundra.
In fact, it took about just 1.5 years of warming for the soil carbon content to reduce as plant biomass increased, leading to subsequent increasing abundances of enzymes and genes involved in elemental cycling. And this was naturally associated with higher decomposition rates and equally high microbial activity, a dynamic phenomenon that strikingly contradicts the sluggish behavior in winter.
| PARAMETERS | SHORT TERM | LONG TERM |
| Relative collective growth | Increased by 36% | Increased by 151% |
| Bacterial taxa in the soil | Increased growth by 64% | Increased growth by 18% |
| Growth of unique bacterial taxa | 118 taxa more than the control | 37 taxa less than control |
| Growth with respect to warming by 1.5 ℃ | 15% increase | 12 % increase |
As seen from the table, changes within the system in the tundra during Arctic amplification both—– short and long term, affect the microbial taxa and other forms of life greatly, in a radical way. But are these changes truly enabling the evolution of life in the tundra in a positive light? It doesn’t seem so, at least not with the rapid carbon (im)balance nor with the plant encroachment. But on the other hand, ironically, the flourishing of the inherent microbial community brings out a sense of new hopeful beginnings of the spring; hoping to discover those rare extremophiles previously covered deep within the cold layers of the tundra, doesn’t it?
This is why we need proof and data, and further probing into similar works like this.
“The microbial responses to Arctic warming must be understood to predict the effects of future microbial activity in a warming Arctic”, is how the scientists emphasize the importance of their work in decoding life and predicting the future in the tundra ecosystem, as well as to mitigate the damages owing to climate change.
Finally…
Overall, the drastic changes occurring in the Arctic over the past few years have certainly attested that winter is no longer prevailing in the tundra. But, will this growing season of microbes and encroaching plants sustain as a concrete form of evolution for long? Only time (and surely new research) can tell….
Link to the original post: Propster, J. R., Schwartz, E., Hayer, M., Miller, S., Monsaint-Queeney, V., Koch, B. J., … & Hungate, B. A. (2023). Distinct Growth Responses of Tundra Soil Bacteria to Short-Term and Long-Term Warming. Applied and Environmental Microbiology, e01543-22.
Featured image: https://kids.frontiersin.org/articles/10.3389/frym.2022.703805
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