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A group of scientists warned on Tuesday, October 3 that massive tree planting, particularly in tropical regions, could do more harm than good. (illustrative image)
ENVIRONMENT – Around the world, tree plantations have become a preferred way for companies and individuals to offset their greenhouse gas emissions. Even US Republicans, who are notoriously skeptical about climate change, have introduced a bill that would support the planting of a trillion trees worldwide.
However, a group of scientists warned on Tuesday, October 3, that massive tree plantings could do more harm than good, especially in tropical regions where monocultures can lead to the disappearance of complex ecosystems.
Forests that become “homogeneous masses”.
“Society has reduced the value of these ecosystems to a single parameter: carbon,” write the scientists from British and South African universities. Carbon sequestration is “a small part of the essential ecological functions that tropical forests and grassland ecosystems perform,” they explain in an article published in the journal Trends in Ecology and Evolution.
One of these scientists, Jesus Aguirre Gutierrez, cites examples from southern Mexico and Ghana, where once diverse forests “transformed into homogeneous masses.” This makes them “highly susceptible to disease and has a negative impact on local biodiversity,” the researcher from the University of Oxford’s Institute of Environmental Change told AFP.
These plantations are dominated by five tree species, selected primarily for their value in wood and paper pulp or for their speed of growth. The trees will eventually be cut down, releasing carbon. These species include teak, which can take precedence over the original species and “pose additional risks to native plants and the ecosystem,” adds Jesus Aguirre Gutierrez.
First, protect existing forests
Further points of criticism relate to the global lack of space for the numerous large-scale planting projects, the planting of poorly adapted seedlings or the improper use of meadows and wetlands in forest areas.
So is there no point in planting trees? Not so fast, says Jad Daley, whose organization American Forests claims to have planted 65 million trees. “Nobody is saying that forests alone can save our environment,” he told AFP.
But he criticizes “inaccurate” reviews that ignore carefully coordinated projects with native species in reforestable areas. “Much of the reforestation is due to the loss of forests that do not regenerate without help,” he emphasizes. “We don’t just plant trees where we want to capture carbon.”
Some are striving to balance the pros and cons, such as the Royal Botanic Gardens of Kew (UK) and the organization BGCI (Botanic Gardens Conservation International), which propose ten “golden rules for forest restoration”. In particular, it is recommended to avoid meadows or wetlands, to give priority to natural regeneration and to select resistant trees with high biodiversity.
And everyone agrees on the first of these golden rules: Protect existing forests first. “It may take more than 100 years for these forests to recover. “So it’s important to protect what we already have before planting more.”
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