In a recent article in The Conservation the author Bonnie Waring states that if we maximize the storage capacity of the earth’s vegetation (especially by planting trees), we’d sequester about ten years of global emissions at current rate.
After that there could be no further increase in carbon capture. In addition, large scale planting can have a devastating effect on biodiversity. To avoid such damage, we must refrain from establishing forests where they naturally don’t belong and avoid ‘perverse incentives’ to cut down existing forest in order to plant new trees. Keeping in mind that naturally established forests contain more species of plants and animals than plantation forest and often contain more carbon.
So it makes sense to prioritize saving existing mature forests over planting new trees and to be realistic about the potential of nature based solutions
More reading: https://theconversation.com/there-arent-enough-trees-in-the-world-to-offset-societys-carbon-emissions-and-there-never-will-be-158181