Non-native species are now part of Dutch biodiversity

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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 non-native species have now become established in the Netherlands: species that do not naturally occur here and arrived as a result of human activity. They may have been introduced deliberately or unintentionally. For managers of public green spaces and waterways, the presence of non-native species is relevant because some can spread rapidly and cause problems.

Image for illustrative purposes, generated using AI

The Netherlands is home to approximately 43,500 established species of fungi, plants, animals and other organisms. Bacteria are not included in this figure. Animals make up the largest group, with around 27,500 species. There are also 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 non-native species is invasive

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

A non-native species is not automatically an invasive alien species

Insects are the largest species group

With more than 20,000 species, insects are by far the largest group among all species found in the Netherlands. In terms of species numbers, they account for almost half of Dutch biodiversity. Arachnids, crustaceans and nematodes are also species-rich groups.

Plants include more than 1,600 species of vascular plants and over 600 mosses. Of the established non-native species, around 15 percent are vertebrates. These are mainly amphibians, mammals and fish.

For green space management, the key issue is which non-native species behave invasively

Oriental bittersweet shows when a non-native species becomes a problem

A recent example of an invasive alien species is Oriental bittersweet (Celastrus orbiculatus). The climbing plant was recently found in two drinking water catchment areas: near Meijendel in South Holland and Ruinerwold in Drenthe. The species can grow up to three metres per year and climb to the tops of trees.

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

In Meijendel, site manager Dunea completely dug out the Oriental bittersweet plants. In Ruinerwold, the plants are already much more developed, with stems more than five centimetres thick. Waterleiding Maatschappij Drenthe has therefore chosen to cut the stems and remove new root shoots over the coming years.

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

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