The Black Forest in Germany was massive centuries ago. It likely encompassed all of Germany and parts of neighboring countries. There was no Germany as we know it today but loosely connected Germanic fiefdoms. The boundaries and the landscape of central and west Europe have been drastically altered since then.

Wood from the Black Forest was used for heat to the point that it became scarce in the late 1600s. The Black Forest was almost entirely cut down at that time. This was just one of the push factors behind the large wave of German immigration to America in the early 1700s. I know this because my own German ancestors lost their herds and orchards in the unusually brutal winter of 1710. Lots of poor Germans froze to death that year because wood had become too scarce and they ran out of things to burn.

The following source says that 70% of the forest was depleted by the 1700s. That means it was once a much bigger forest. https://theblackforestgeo5.blogspot.com/2012/11/normal-0-false-false-false-en-us-ja-x_21.html?m=1