It's actually a clever plan. They will destroy ecosystems on the way so its not _perfect_, but it's feasible and will likely work if they fuccessfully find the right kind of tree to start the forest. Greenland is doing it too[1], with a lot of setbacks, but they are starting to recover (albeit slowly)
China even has a program in place to plant trees along the Gobi dessert to stop it's expansion. https://en.wikipedia.org/wiki/Three-North_Shelter_Forest_Pro.... That will help with the number (closer to 200 tree/person) since they plan to plant 100 billion trees by 2050 http://www.theplaidzebra.com/china-is-building-a-great-green...