I've seen forest sprout up in abandoned dead areas without any human assistance. It takes about 2 decades of being left alone to get enough young growth to start being called a forest, but not really more than that. And it would take generations more to be called an old "real" forest, but it has to start somewhere. To rehabilitate long dead soil it might take what you describe, but turning an old meadow into a wild area that will eventually turn into a forest, does not need human intervention. It just requires to be left alone. In my climate that is. Claiming that forests can't grow without human assistance is absolute nonsense, forests grew just fine before humans came along.
And as further proof that I don't live in fantasialand with my belief that forests can grow without human intervention, here's 2 links with examples: https://en.wikipedia.org/wiki/Passive_rewilding https://www.rewildingmag.com/passive-rewilding-natural-reforestation/