Now 2,083 hectares, but the raised moor area was once 170,000 hectares and extended far into Germany. Almost everything has been excavated and with that nature disappeared and agricultural land came back. Except for the Bargerveen.
The Bargerveen suffers from the strongest overload of nitrogen in Drenthe. In 94 percent of the nitrogen-sensitive area there is a strong overload of nitrogen. That amounts to more than twice the permitted nitrogen level. In some places it is even four times the standard.
There is too much nitrogen coming in to maintain nature, let alone restore it. For the grass areas, there will be desiccation. The deterioration in the raised bog is not only due to nitrogen, but also to water management. A number of bird species cannot be maintained with the current nature restoration measures.
An area of 222 hectares. Created by too much grazing of sheep and sod extraction in the 18th and 19th century. Heath and sand drifts. A sand drift is an open place where there is no vegetation. The wind has free rein to spread the sand further. The limited size of the area is already a concern – sand drifts generally need a lot of space – but nitrogen makes the sand drifts grow faster with plants.
Large areas of drifting sand heath with heather go well, because they are ‘stable’. But the quality of nature is deteriorating on both the heathland and the sand drifts. And if nitrogen precipitation does not decrease, nature in those areas will deteriorate further. The lichens on the Drouwenerzand are already not doing well.
With 3,768 hectares, it is the largest area of wet heathland in Western Europe. The area is on higher sandy soil.
Some of the heath species are stable, but the quality is declining. It is not easy to determine how different types of fens are doing. What the researchers do know: the overload of nitrogen on the fens is 100 percent. There are as yet no measures that can counteract the negative effects of the heavy overload.
Various forest species are stable, but they also suffer from acidification or eutrophication. Almost all nature on the Dwingelderveld is suffering from desiccation, despite all the measures taken in recent years to make parts of the Dwingelderveld wetter. The conservation objective has not been achieved for a number of bird species, such as the black woodpecker and the wheatear.
The nitrogen makes the soil more nutrient-rich and more acidic. Grass benefits from this, at the expense of heathland and shifting sands. It is expected that without measures the heathland and the drifting sand will disappear, and with it the living conditions for animals. Some plants have even disappeared due to acidification of the soil, such as the rosary and sweet-smelling night orchid.
Beekdalen nature reserve of 351 hectares. One of the four nature reserves in the Netherlands where lime marsh is present. This is internationally regarded as a highly endangered type of nature, full of special and often endangered species.
Five of the seven types of nature in the Elper river basin cannot be maintained with the current measures. The moist heathland, blue grassland, sparse grasslands and lime marshes will not survive in the long term due to too much nitrogen and desiccation. Deterioration can already be seen in both quality and surface.
1,754 hectares of higher sandy soils with heath and forest. There is a former airfield from the Second World War. The runways have remained in place and a lot of flora has developed on them. For example orchids, ferns and the rosaries. The area is also rich in butterflies, including a form of the common blue that only lives here and on Terschelling.
In this area, too, there is a deterioration of all nature species due to too much nitrogen fertilization and desiccation. Almost all forest and vegetation types are stable in surface area and (moderately) stable in quality. Both moist heather and dry heather, beech, oak and holly are doing badly. Plants and animal species cannot be maintained in this area if the nitrogen deposition remains the same as it is now.
The spotted white-beaked dragonfly and crested newt both have stable populations in the area. But neither of them is a fan of an ‘acidic’ living environment and besides desiccation and eutrophication due to nitrogen, acidification of their habitat is also lurking.
Probably the oldest existing forest in the Netherlands. The forest of 46 hectares is mainly on higher sandy soils. The beech and oak forests with holly are stable but slowly declining. Nitrogen is also the culprit here.
The 780-hectare Mantingerzand mainly consists of higher sandy soils. The shifting sands of the Mantingerzand differ from most other areas in the Netherlands, because the ‘dunes’ in the area do not seem to have risen as high.
Various types of heathland do not win from grassification. The grass grows well on nitrogen. In some places there are positive results because there is sod or because there is regular grazing by cattle. The quality of the sand drifts, drifting heaths, scrub heaths, crow heaths, moist and dry heathlands is decreasing.
Despite the interventions in nature to restore the area, it is not possible to combat acidification, eutrophication and desiccation.
This higher sandy soil forest of 26 hectares is home to the largest holly tree in Europe. Since 1962, nothing has actually been done about management in the area. Nature in the Norgerholt, which mainly consists of beech and oak trees, is allowed to take its own course.
Both the high moor forest and the beech and oak forest with holly are stable in surface area and quality. The nitrogen pressure is high, but the forest does not seem to be affected too much yet. However, with today’s knowledge and measurement method, it cannot be ruled out that the same amount of nitrogen as now will have negative consequences for the Norgerholt in the long term.