The old moor, natural forest and forestry
Almindingen is a natural forest area and has been more or less permanently forested since sometime after the last ice age. However, when the forest supervisor Hans Rømer started replanting Almindingen in the early 1800's, the forest had shrunk to only about 165 hectares in the area around Christianshøj. It featured oak, probably durmast oak, as well as hornbeam which, despite its name, belongs to the hazel family.
The rest of the "forest" consisted of heather and juniper, what was known as moor. The moor was the result of hundreds of years of felling of trees for wood and timber, and of the fact that the peasants used the area to put the livestock out on grass for the summer. Enebærskoven is a part of the old moor, which has been preserved.
The replanting was done according to the German model. The method was called "systematic forestry" and the idea was to divide the forest into smaller areas of trees of the same age and the same species. This made forestry more rational, as entire areas could be felled at once from one end, instead of using the old-fashioned way where the forestry owner would judge when to cut down individual trees in the confusion of old, young and in-between trees of different species, of which a natural forest consists.
The systematic forest has been the ideal in Almindingen and in Denmark's forestry industry, generally, up to the turn of the millennium, when the focus in the state-owned forests began to shift from commercial timber production to more natural forestry.
In addition to Enebærskoven and the area around Christianshøj, which are remnants of moor and the original nature forest, respectively, the oldest parts of the forest originate from the time of Hans Rømer. These include, amongst others, the durmast oaks on Ekkodalsklippen and the beech forest at Koldekilde.
Besides oak and beech, Rømer and his successors also planted birch, ash, hazel and various conifers. Throughout the 20th century, the conifer has been the most widely used forest tree, and, for this reason, Almindingen comprises large areas of common spruce. However, common spruce is not native to the Danish nature and is virtually without value as a habitat for insects, birds and fungi. The oak, on the other hand, has more than 1,000 species attached to it.

As the common spruce is cut down, the felled areas will be largely left to self-seed and natural forestry, and the individual marking of trees for harvesting will be reintroduced. Over time, this will create a much more natural and abundant forest.
Read more about Natural Forestry here (in Danish)