|Skogstäcke över tiden i Sverige. Source: Kaplan and co-workers.
The Swedish forestry industry sometimes seems to think time began in the 1920's. After heavy logging in the 19th and early 20th centuries, the standing volume was then very low indeed. For that reason, the industry poses that there never has been so much forest in Sweden as there is now, implying that there is no problem in logging even more. But according to research from 2009, over 70% of Sweden was covered by forest a thousand years ago, forest that without a doubt held a much larger biodiversity than the forest landscapes of today. The current amount is about 55% productive forest land (but note that the Swedish Forest Agency uses a different definition of forest, so their numbers can't be compared with these). This does not mean that Swedish forests were untrodden by humans a thousand years ago, but there was less human influence than in many other parts of the world, particularly in northern Sweden.
We don't have to go a thousand years back to find a larger forest cover. Historians Per Linder and Lars Östlund at the Swedish Agricultural University write "during historical times, Sweden has never had so little old forest, as few large trees and as little dead wood as they do now". According to this paper, forests in 1991 contained only about 10% of the large trees and dead trees that would be found in unexploited forests. Despite recovery since 1920, it is likely that there is still less timber volume in northern Sweden than there was around 1860 - and today's forests have a different structure. Now we have young trees standing close to each other at short distances instead of old large trees with a lower density. Obviously forests were used by humans all over Sweden in earlier times, but usage was of a different character and magnitude than present-day forestry.