Trees & Vegetation

[Sakkura]

I doubt anyone here has seen a real forest.

The thing is, old growth forests still do exist in Europe even if 99% of it is gone due to fleet construction, industrialisation etc.
The biggest trees in them are indeed bigger than in other forests, but nowhere near as huge as RTW shows them. And of course, a stable natural forest will have a broad mix of tree ages as well as dead trees.

The problems for armies passing through would probably be just as much from the so-called pit-and-mound topography that is formed by falling trees (and ant hills I guess), as well as any fallen trees that may be blocking movement now and then. Also, some of the original European forest types tend to have boggy, wet areas inside them. Floods of the forest floor in broadleaf forests were common especially in spring.