Forests and other land vegetation are natural 'sinks' for greenhouse gas emissions. However, researchers have been concerned about the trade-off of carbon dioxide gas absorbed by trees resulting in accelerating the growth rate of trees but shortening their lifespan.
Scientists from the University of Leeds published their study in the journal Nature Communications. Trees absorb nearly one-third of carbon dioxide emissions from burning fossil fuels. However, the increasing concentrations of carbon dioxide absorbed by trees and high temperatures make them mature quicker.
The researchers fear that trees can no longer alleviate the effects of increased levels of greenhouse gas emissions for as long as predicted. They examined more than 200,000 tree ring records from various species, ranging from tropical moist forests to arctic forests, around the world, and discovered that the trade-off between tree life spans and growth was evident in nearly all of them.
Vulnerable Young Trees
People have greatly benefited by the ability of trees to absorb carbon gas emissions for years, said Steve Voelker from the State University of New York College of Environmental Science and Forestry. However, the increasing rate of carbon dioxide in the atmosphere is likely to be on the wane as slow-growing, and persistent trees are supplanted by fast-growing but vulnerable.
Voelker compared their research to the study of the tortoise and the hare with evidence indicating that trees growing at faster rates are more vulnerable. On the other hand, 'slower growing trees have traits that allow them to persist.'
The team had also concluded that as trees reach their maximum potential size, they have an increased risk of dying. Fast-growing trees also seem to have fewer defenses against natural causes like insect attacks, invasive species, diseases, and drought.
Other factors of destruction also make the trees vulnerable, especially since the Earth's average surface temperature had increased by 33 degrees Fahrenheit. The warmer temperature has triggered severe droughts, heatwaves, rising sea levels, and superstorms.
READ: Forest Contribution to Seasonal Carbon Flux Depends on Location, Study Says
Forest Carbon Sink
David Lee from Metropolitan University in England said that current climate models are predicting that forests will continue or increase their ability to store carbon. The research, which Lee was not part of, shows the opposite—that increased carbon dioxide levels compromise forests as a carbon sink.
This means that planting more trees or decreasing deforestation to offset greenhouse gas emissions from fossil fuels really does not stand up to scientific scrutiny, says Lee. According to the Global Forest Watch, in 2019, trees that have grown old were being destroyed every six seconds by the football pitch. That equates to nearly 14,600 square miles in total.
Keith Kirby from the University of Oxford said, "We cannot rely as much on increased growth per unit area to maintain and enhance the forest carbon sink potential, but this might be offset by slowing deforestation and increasing the expansion of the extent of forests where this can be done in a sustainable way."
READ: Tropical Soils Are Highly Sensitive to Climate Change
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