Oostvaardersplassen

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The Oostvaardersplassen

The Oostvaardersplassen is a nature reserve in the Netherlands. Despite its young age (it is in a polder which was only created in 1968) it already has international importance as a European wetland.

The Oostvaardersplassen can be divided into two areas: wet and dry. In the wet area along the Markermeer, there are large reedbeds on clay, where moulting geese often feed. This area is also home to Great Cormorant, Common Spoonbill, Great Egret, White-tailed Eagle and Eurasian Bittern, among many other animals.

[edit] History

Before the establishment of the reserve, the dry area was a nursery for willow trees, and in the first year hundreds of seedlings could be found on each square metre. This led to concern that a dense woodland would develop, significantly reducing the value of the habitat for water birds. To avoid this, the park's managers brought in a number of large herbivores to keep the area more open, including Konik horses, red deer and Heck cattle. These large grazing animals are kept out in the open all year round without supplemental feeding, and are allowed to behave as wild animals (without, for example, castrating males). The ecosystem developing under their influence is thought to resemble those that would have existed on European river banks and deltas before human disturbance.

[edit] Large herbivores

Before they were driven to extinction, large herbivores in this part of Europe included the tarpan (wild horse), wisent (European bison), red deer, elk (known as moose in North America) and aurochs (wild cattle). The tarpan and aurochs are extinct, but Konik horses and Heck cattle are able to act as functional equivalents, occupying a similar ecological niche. The only native large herbivores now missing from Oostvaardersplassen are the elk, the wild boar and the wisent. It is unlikely that elk will be introduced, but there is hope for wisent as it fills a different niche from cattle. There is a chance that the wild boar will find its way from the Veluwe.

[edit] Natural processes

Carcass of deer that died in winter

Given that the Oostvaardersplassen are effectively under the sea level, many of its primary processes have been regulated. As the wetlands have been so spectacular, a dyke was made around it to prevent the process of groundwater-related subsidence. While this had temporary advantages, it created a water body with no open connections to the rest of the polder and the negative effects are only now being understood.

The cattle, deer and horses have multiplied in the Oostvaardersplassen. However there is a limit to the number of animals the area can sustain. In the absence of natural predators the rangers shoot animals that are unlikely to survive. It is quite natural for 30% to 60% of the population to die in this way. After a die off, the vegetation has a chance to rebound and this will get the first natural forestation of the area underway.

[edit] Future development

In many ways are the Oostvaardersplassen an isolated area; it is in a polder and there are currently no corridors to other nature reserves. As part of the "Ecological Main Structure" plans for what is to be the "Oostvaarderswold" a connection will be created to the Horsterwold. Eventually this should allow deer to move all the way to Germany and France.

The advocates of natural processes are also planning for the wet part of the Oostvaardersplassen to be drained. It is expected that the natural subsidence will lower the ground level and that this will result in a more natural and dynamic system.