MG forests are no longer removing carbon from the atmosphere and becoming a source of gas, study says – 12/18/2020 – Environment

Over the past few decades, forests in various regions of Minas Gerais have had increasing difficulties in fulfilling one of their most important ecological tasks: removing CO2 (carbon dioxide or carbon dioxide) from the atmosphere and thus mitigating the warming of the planet.

In some cases, such forests did not act as the usual “drains” of CO2, but acted as a gas source and fed a cycle of carbon dioxide emissions that is likely already negatively affecting these environments. It is something that mainly intensifies in the drier forest areas, in the transition zones between the Atlantic forest and other environments like the cerrado and the caatinga.

“People never believe that climate change is happening on their side, in their surroundings, in their city,” says Rubens Manoel dos Santos, professor at the Federal University of Lavras (MG) and one of the authors of the study. “It seems like it is something that only affects distant places like the Amazon or Africa. But our work shows that this is already part of everyday life. “

The worrying results have just been published in an article in Science Advances. Santos and his colleagues examined 32 different forest areas in the Minas Gerais area (see infographic) as part of a temporal analysis that has been carried out since 1987 depending on the region. Each location was analyzed for an average of 15 years.

As Vinícius Andrade Maia, also author of the study, explains, the various forest sections are largely part of the Atlantic forest, but include a wide variety of physical properties (soil types, rainfall, etc.) and vegetation. There are more closed and humid forests, so-called perennials (which do not lose their leaves in the dry season), to so-called half- and deciduous forests, which lose part or most of their leaves in the months with little rain.

In normal situations, forests often sequester carbon dioxide from the air as trees grow. This is because CO2 is used as a raw material for building plant organisms through the process of photosynthesis.

Over the past centuries, the amount of this gas in the atmosphere has increased greatly due to the burning of fossil fuels (gasoline and coal) due to humans. Anti-scientific conspiracy groups often minimize the problem by saying that the carbon dioxide “left over” in the atmosphere simply helps forests grow faster and benefits agriculture.

The forest mining scenario makes it clear how simple and misleading this idea is. During the decades that the forests were studied, the levels of CO2 in the atmosphere did not stop increasing. At the same time, there were temperature and precipitation fluctuations (rain) – in short, more heat and less rain in the reporting period. By 2013 there was an increase in so-called carbon stocks, that is, the carbon dioxide that was “collected” from the forests. From then on, the calculation became less and less positive: the forests lost more carbon than they collected. In the end, the net value (the sum of sequestration and carbon loss) for deciduous and deciduous forests has become negative: they have become sources of CO2 for the atmosphere.

“The increase in CO2 in the air doesn’t necessarily translate into growth. Plants can get used to the new gas values ​​and cannot grow beyond normal values, ”explains Maia. In addition, the change can also increase competition for space between trees, which also leads to higher mortality among them.

Finally, it must be remembered that climate change also increases the likelihood of extreme events such as prolonged periods of drought or very heavy rainfall, which lead to severe mortality and decrease the growth of trees. “It is too early to say what the main causes are. We have to continue the work to determine this, ”says the researcher.

In any event, the data underscore the need to take action against the uncontrolled emission of gases from global warming and to protect environments such as the Atlantic Forest, which have already been severely damaged by the expansion and deforestation of agriculture. We are a family business.

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