What exactly is happening to the trees?
An international team of nearly 100 scientists has discovered that the increased concentration of in the atmosphere has created a resource-rich environment for plants in the Amazon Valley. Since the 1970s, the base area of trees in the region has been increasing by an average of 3.3 percent each decade.
“We knew that the total amount of carbon stored in the trees of untouched Amazonian forests had increased. The entire forest has changed,” said Tim Baker, a co-author of the study and a professor of tropical ecology and conservation at the University of Leeds (UK).
The number of has also increased, which scientists consider good news. This means that Amazonian trees are more resilient to global warming than previously thought, says co-author Beatriz Marimon, a professor of tropical plant ecology at the State University of Mato Grosso (Brazil).
Meanwhile, previous studies have shown that rising temperatures and CO2 levels are pushing the tropical forests of the Amazon closer to a critical tipping point, where the local ecosystem could transform into a savanna within the next 100 years. However, it turns out that the trees are simultaneously benefiting from the changing climate, sequestering vast amounts of carbon and growing larger.
How did scientists find this out?
The team collected data from 188 plots in the tropical forests of the Amazon, measuring the base area of trees, or the area they occupy with their trunks on the forest floor. Monitoring began in 1971 and concluded in 2015. Over various time periods, scientists observed different plots, with the longest continuous monitoring lasting 30 years, as reported by Live Science.
The team of scientists specializing in tropical plants predicted several possible outcomes. According to one scenario, only large trees would benefit from the increased CO2 levels. They have greater access to light and nutrients, making them more resilient to changing conditions.
In a second scenario, the smallest trees would gain the most from the increased CO2, as their resources are so limited that any increase in atmospheric carbon would be more effective for them than for larger trees.
The third possible outcome is a combination of these scenarios.
As the results showed, the third scenario is currently prevailing. According to Professor Marimon, trees in untouched forests have become larger. Even the largest trees, which are typically more vulnerable to climate events like droughts and lightning, are thriving in areas where there is no deforestation.
However, researchers believe that over time, the increase in trunk base area may become more pronounced in large trees, which will then begin to dominate the ecosystem.
“Large trees are extremely beneficial for absorbing CO2 from the atmosphere, and this is confirmed by the research,” noted co-author Adriana Esquivel Mühlbert, an assistant professor of tropical plant ecology at the University of Cambridge. “Despite concerns that climate change may negatively impact trees in the Amazon and undermine their ability to sequester carbon, the stimulatory effect of CO2 on their growth remains. This indicates the remarkable resilience of these forests, at least for now,” she added.
However, as researchers warned, the situation may soon change: in the coming decades, a slowdown in tree growth and an increase in mortality rates are expected. This could occur due to a combination of factors such as heat stress, water shortages, , and storms, the frequency and intensity of which are already increasing.
Scientists believe that, in addition to reducing carbon emissions, the best way to protect the Amazon forests is to keep them intact.
The findings of the study were published in the journal Nature Plants.
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