This is in Eastern Australia, where we have native wombats, macropods, possums, as well as wild/feral pigs, goats, rabbits, and the occasional deer, along with parrots and fruit fly that tend to destroy fruit with potentially viable seed. But at least we don't have moose, I guess.

Fencing off an area to stop the ground-based pests has impressive observable results even after a couple of years - but it's very expensive, and fences decay within the lifetime of many of the pioneer trees.

So de jure reforestation, while a nice principle, isn't feasible in all environments.

Further complication in many areas desperately in need of reforestation is periodic drought -- Australia and the Americas have the famous El Niño / La Niña cycles to contend with, where we regularly have several consecutive years with minimal (or at best unreliable) rainfall. Again, this is an excellent candidate for a very cheap mass seed distribution system that can simply be re-run each spring until a favourable rainfall pattern produces a good result.