Lost Microbes are Eroding Amazon’s Ability to Capture Carbon



Beneath the lush forests of the Amazon is a whole different level of diversity that new research says may be one of the keys to understanding how to stem the global impacts of deforestation.

The Amazon rainforest is known as one of Earth’s hotspots for diversity. It contains at least 40,000 plant species, 5,500 animal species and 100,000 insect species. These have been a great source for the discovery of new medicines, with at least 120 approved for use. Despite its great plant and animal diversity, it is one of the least understood ecosystems for its microbial diversity. There are 100 million microorganisms in a single gram of forest soil, making them the largest repository in the world of novel genes.

These microbes are essential to nutrient recycling. They decompose dead organic matter, through a process called mineralisation, releasing mineral nutrients that plants absorb through their roots, allowing the forest to grow. As trees grow, they capture carbon dioxide from the air through the process of photosynthesis, and, in the Amazon, this process occurs at impressive levels. Owing to its size, the forest absorbs 1.5 billion tons of CO2 from the atmosphere every year – making it the largest terrestrial sink of this greenhouse gas.

Large amounts of nitrogen are needed to achieve the Amazon’s role as a carbon sink. In the rainforest, that comes primarily from the natural process of nitrogen fixation performed by microbes called diazotrophs. They break apart molecules of nitrogen that is essential for all living things. But, up until now, no one has looked at how the function of these microbes changes when a rainforest is converted to a pasture, something that is happening at an alarming rate in many parts of the Amazon.
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