The problem here is that areas for reforestation are not plant_nursery. A plant_nursery is e.g. this place (https://www.openstreetmap.org/way/53255863) where plants are grown and then relocated to different places in the city.

But the areas here are just places with smaller trees and there is probably no intention to sell and relocate the trees in a few years. 

So a reforestation area is just something different than a plant_nursery.