there's also landscapes that shouldn't be forested https://www.theflowcountry.org.uk/flow-facts/flow-fact-1/ - in the past, tax breaks led to attempts to drain and reforest the flow country (an enormous peat bog in the north of scotland). This would have released CO2 when the peat was damaged.

There's plenty of land further south being reforested tho.

I think they probably included those islands when they calculated the forest cover. I’d be very surprised if they didn’t actually

not just in Scotland. The Forest (eh) of Bowland, in the North of England, is continuously swept by strong winds. Other areas like the Goyt Valley seem to struggle in a similar way: they can be prettly lush inbetween hills, but as soon as the landscape opens a bit they become very raw.