u/Schroinx

For much of Europe, this applies, as our landscapes are culture dominated and has been for centuries. Rewilding the #hydrology is the first and most key step, to give it back to nature. Not with a big fancy expensive intervension, but closing a few ditches and make some BDAs to rebuild the level of the watercourse in some places to reconnect the water course to its floodplain and let it meander.
Get it a few cattle, horses & pigs to keep the growth at bay.

Not so much primary forest in Europe, but also as this was not a nature type as prevalent as previously thought, as mixed wood and grassland were dominating, due to large herbivores being prevalent in the ecosystem until the arrival of humans.
There is also the second question, how to care for old growth forest.
Also the link leads to an article on research gate for the interested.