Inferior forests are better than no forests.

You don’t have to take an empty field and plant 100k trees. You can go to where chestnuts used to grow, have some volunteers plant some over time, say 100 every month in an area. Over the course of 10 years, we’ll get some data.

Don’t let great be the enemy of good.

A healthy forest comes from strict conservation laws, confiscation, expropriation, etc. When land is secured, what to plant is a technical detail.

Achieving a good approximation of pristine natural forests might have a lower priority than the variable needs to increase rare plants, provide an habitat for rare animals, make the forest robust against climate and geological hazards, dealing with people with friendly (e.g. edible fruit) or hostile (e.g. thick vegetation to discourage secret hemp cultivation) features, etc.