The Jutish heath was a massive wasteland for more than 5000 years, it had wandering dunes, dust balls and swamps caused by it having a lot of rain and really poor drainage. The former heath today are woodland in the areas, which was too hostile for agriculture, the swamps was drained, and the former dunes and dust balls are covered by a thin layer topsoil. On Bornholm where the central heath was on top of rocky basement, the former heath are today one large forest.
Of course this hard work wasn’t just people who decided to transform the heath to agricultural land, it was pushed by the state and by the “Højskole” movement. But if it had been left to the big landowners the Jutish heath had stayed a place to graze their cows and sheep just as the Scottish highland. But because the state had created land reforms which gave the tenant the land, they worked these people had a incentive to transform hostile wasteland into farmland. Which is why Denmark was the Scandinavian country, which sent the least people to the Americas, because the lack of Norwegian and Swedish colonies, didn’t stop those countries from sending a massive number of people to the Americas.