It has been argued that planting one trillion trees can protect the planet from global warming, but environmental experts warned that planting trees could not be a 'all-around remedy' to address global warming.
It also suggested a strategy that would be more efficient to protect and maintain the entire intact forest from destruction than to force it to increase.
According to the University of California, Santa Cruz, Professor Karen Hall, a forest restoration expert at the university, said in a recent issue of the journal Science, "It's just a piece of a puzzle (planting trees to combat global warming)." "We can't get out of climate change by planting trees."
Professor Hall said, "The long-term management plan is needed to fully realize the benefits of large-scale tree planting." He stressed that it should be done carefully. "Planting trees is not a simple solution, it needs to be as realistic as what we can and can't achieve as much as it is complex."
In addition, trees have positive effects such as increasing biodiversity and improving water quality, but depending on where and how they are planted, they can be harmful to existing ecosystems and species, reducing water supply, taking user's land, and increasing social inequality. He pointed out that it can also cause side effects.
Prof. Hall gave four principles to be followed in planting trees in a commentary jointly made with Professor Pedro Brancalion of the Department of Forest Science, University of Sao Paulo, Brazil.
First of all, it was recommended that forest clearing and forest erosion be minimized as much as it would be more ecologically and cost-effective to protect and maintain the whole forest than to plant or transplant new trees.
It was also encouraged to consider planting trees only as a small part of various environmental solutions. It is true that planting trees is one of the best ways to offset the greenhouse gases caused by human activity, but it must be borne in mind that the amount that can be reduced is only a fraction of what is needed.
He also said that when choosing a land for planting trees, it is necessary to find a balance between ecological goals and social demands, share goals with local participants from the planning stage, and carefully promote and monitor them.
"Much of the proposed land for planting trees is already being used for crop cultivation, timber production, and other activities, so planting ideas should also consider how landlords can get alternative income," said Professor Hall.
"The first thing we can do is to maintain the existing forest, and then let the trees grow back where they used to be," said Professor Hall, who is well versed in the restoration of tropical forests among forests.
"In many cases, the trees recovered by themselves," he said. "Look at how much of the forest in the eastern United States, which was destroyed 200 years ago, has recovered, even if it wasn't actively planting trees."
"Where trees are severely destroyed, it is necessary to plant trees, but this is the most expensive and often unsuccessful, and should be the last option," he said. "You have to be considerate about how to restore the forest."
"To reduce the pace of climate change, we need a broader strategy, starting with reducing fossil fuel use," he said. "Trees are only a small part of a broader strategy."