It's interesting to note that these are not natural forests, but essentially man-made tree plantations, reforested since the 18th century after the natural forests had been eliminated in the centuries before mainly because of ore mining. Same story further to the south-east in the Ore Mountains.

Getting rid of the spruce tree mono culture and letting a mixed forest regrow will be a good thing even if it will take a century or more (that's at least what the strategy seems to be in Ore Mountains).