Higher tree line causes bacteria in mountain lakes to emit more CO2
Published: Wednesday, May 8th 2024, 16:20
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The rising tree line is changing the chemical composition of mountain lakes. According to a new study, this could lead to the lakes releasing more CO2 into the atmosphere.
This discovery is all the more important as there are thousands of such lakes on Earth, the Swiss Federal Institute of Technology Lausanne (EPFL) announced on Wednesday. However, further studies are needed to quantify the possible impact of this effect.
Due to global warming, the tree line is rising by ten to 100 meters every year, depending on the region. Forests are thus moving ever closer to the high-altitude lakes. In a study published in the journal "Nature Communications", researchers from EPFL have now investigated the effects of this rise in the tree line on lakes for the first time.
Bacteria become inefficient
This is because the organic carbon in the soil has a different composition depending on whether it is in a forest or a meadow. When it rains or the snow melts, the organic carbon contained in the soil is washed into the lakes. Carbon plays a crucial role in lakes as it serves as food for bacteria, as the university explained.
Until now, however, it was unclear how the bacteria in the lakes reacted to the change in composition. To find out, the EPFL researchers led by Hannes Peter collected water samples from mountain lakes and dissolved organic carbon from the soil both above and below the tree line. This showed that the bacteria in the water became less efficient when carbon from below the tree line was dissolved in it. They therefore released more CO2 into the atmosphere.
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