A tame stranger on the moraine

Nature manager and photographer Fokko Erhart has offered to write a blog about nature on our 136 kilometer long route for the walk of wisdom. Below is his first contribution. 

On the lateral moraine near Beek is the thickest tree in the Netherlands. It is a sweet chestnut. This tree species was not originally found in the Netherlands. He is what biologists call an exotic. Because of its nutritious fruits, the Romans brought it with them more than 2000 years ago during their journeys along the border of their former Empire. This sweet chestnut is an impressive tree, especially because of its record size. Any sane person will agree that this tree should stay standing and grow even thicker. Nevertheless, the presence of its peers leads to discussions between nature managers. One wants to preserve the sweet chestnut tree, the other is opposed to this type of tree because it would have an adverse effect on native plants and animal species.

The sweet chestnut (Castanea sativa) what we are talking about here can be found on the lateral moraine near Nijmegen. In the Heerlijkheid Beek in Beek-Ubbergen it stands at the source of the Vossenbergbeek. It is neatly provided with a sign, which states that the trunk circumference is 850 cm, with which it can carry the predicate “The thickest tree in the Netherlands”. This tree is also referred to as a gnome tree. Logical, because under such a forest giant you quickly feel insignificant. Well, gnomes can get quite old, but whether there are gnomes who have actually seen this tree in its early youth (about 475 years ago) remains to be seen.

By the way, this gnome tree is not the only sweet chestnut on the moraine. It is a regular occurrence in the nearby forests of the Wylerberg and Duivelsberg. Two hundred years ago, avenues with sweet chestnuts were laid out here and from there it has spread into the surrounding forests. However, in percentage terms, their share is low; according to the Forestry Commission, they cover only 1% of the total forest area.

Within the Netherlands, however, the sweet chestnut is even rarer and contiguous forests are almost completely absent. However, these types of trees can be found on country estates and in park forests, such as Sonsbeek near Arnhem, ‘s-Gravenland near Hilversum or in the forests on the Utrechtse Heuvelrug.

This chestnut has a special appearance. So keep an eye out for trees with rough trunks, their characteristic lanceolate leaves (see photo) and the prickly husks that lie under the trees from the beginning of October; that protect the fruits.

By the way, these fruits are edible. However, the advice is to first wash the chestnuts with soap, then cut their tip with a knife, sprinkle with some (sea) salt and finally roast them in a preheated oven (approx. 200 oC) for 10 – 15 minutes. After popping, remove the skin. Cooking is also possible, for which 30 minutes is advised. In French cuisine, puré of these fruits is known as crème de mannon. Enjoy your meal! 

Brought by the Romans

The sweet chestnut is not native to the Netherlands. It was brought by the Romans more than 2000 years ago. It was precisely here on the ridge that a number of encampments were established. The Rhine formed the northern border of the Empire and had to be defended against savages. The view was different then than it is today. From the foot of the moraine stretched a 15-kilometre-wide negorij of swamps, streams and riparian forests. Difficult to traverse and therefore an excellent defense of the Roman Empire.

To be wild or to become wild

Before the arrival of the Romans, sweet chestnut was only found south of the Alps. As a result, nature managers are currently having discussions about whether this tree species should remain or be removed.

One school of thought believes that there should be as many native trees as possible in the Dutch forests (i.e. species that are wild). They refer to the “Rio de Janeiro Convention on Biological Diversity”, which the Netherlands signed in 1992. This treaty states that the Netherlands is responsible for the conservation of species and varieties that originate in the Netherlands. Because the sweet chestnut is an exotic species, it is less well adapted to the Dutch climate. And perhaps even more important is the fact that there are not yet many plant and animal species in the Netherlands that have been able to adapt to living together with that sweet chestnut.

The other camp thinks that sweet chestnuts should be allowed to stay, because they have been reproducing independently in Dutch nature for more than 100 years (they have become wild).

For this reason, this species is listed in the Dutch species register as ‘original’. This register has been compiled by a large number of knowledge organisations in collaboration with the Dutch government. This school of thought believes that forest management should focus on preserving the trees that have proven to be able to live and reproduce in the Netherlands. The historical occurrence of such a species is considered of less importance.

Local management

On the Duivelsberg, a compromise has been found for the management of the sweet chestnuts. Within the forest plots, the chestnuts are selected because they are exotic, but they are allowed to remain along the paths because of their ‘recreational value’.

I think it’s a good choice. Finally, it is important that as many people as possible enjoy nature. 

Fokko Erhart