According to the article, Ethiopia was 30% forested at the end of the 19th century, and is now at only 4%. What's unnatural is the current state, and reforesting will help correct that.
Something to note is that the point isn't for every tree planted to survive. It's for some of them to survive. Those trees will then grow and drop leaves in fall, improve soil health, provide a canopy layer for vines, shrubs, herbs and animal life, and self-seed new trees to join and replace them. Over time the system as a whole will grow until it reaches stability. Right now they're at step 1, planting, which comes after step 0, deciding to plant.
We should follow their lead and plant native trees wherever we are.
