Exotic species have become part of Dutch biodiversity

NEWS

ENTREPRENEURSHIP

Heleen Kommers, Monday 31 August 2026

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More than 1,100 species reached the Netherlands through human activity

More than 1,100 exotic species are now established in the Netherlands: species that did not originally occur here and arrived through human activity. This may have happened deliberately, but also unintentionally. For managers of public green spaces and waterways, the presence of exotic species is relevant because some can spread rapidly and cause problems.

Image for illustration, generated with AI

The Netherlands has a total of approximately 43,500 established species of fungi, plants, animals and other organisms. Bacteria are not included in this figure. The largest group consists of animals, with around 27,500 species. In addition, there are approximately 2,700 plant species, 11,000 species of fungi and 2,300 species of diatoms and brown algae.

More than 1,100 species reached the Netherlands through human activity

Not every exotic species is invasive

The fact that a species is exotic does not automatically mean that it causes problems. Only species that spread rapidly and cause damage to nature, health or the economy, for example, are considered invasive exotic species. This distinction is important for green space managers. Well-known invasive species sometimes require intensive management, while intervention is unnecessary for many other exotic species.

Exotic does not automatically mean invasive exotic species

Insects are the largest species group

Of all Dutch species, insects are by far the largest group, with more than 20,000 species. They account for almost half of Dutch biodiversity when measured by the number of species. Arachnids, crustaceans and nematodes are also species-rich groups.
Among plants, the Netherlands has more than 1,600 vascular plant species and over 600 moss species. Of the established exotic species, around 15 percent are vertebrates. These mainly include amphibians, mammals and fish.

For green management, the main concern is which exotic species behave invasively

Oriental bittersweet shows when an exotic species becomes a problem

An example of an invasive exotic species is oriental bittersweet (Celastrus orbiculatus). The climbing plant was recently found in two water extraction areas: Meijendel in Zuid-Holland and Ruinerwold in Drenthe. The species can grow up to three metres per year and climb into the crowns of trees.

The stems wrap around trunks and branches and can constrict the bark and underlying vascular tissues as they thicken. This can weaken trees or cause parts of them to die. Oriental bittersweet can also displace native species in the understorey and hinder natural forest regeneration.

In Meijendel, land manager Dunea completely excavated the oriental bittersweet plants. In Ruinerwold, the plants are much more developed, with stems thicker than five centimetres. Waterleiding Maatschappij Drenthe has chosen there to cut the stems and remove new root growth over the coming years.

This article was previously published on 31 August 2026 on the website of Stad + Groen.

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