Three-year biodiversity implementation programme: from toad ladders to deliberate non-intervention

21 August 2025 News item

If one thing typifies our campus, it is its beautiful green surroundings. The biodiversity project group works to towards a campus where nature and science go hand in hand and publishes an annual implementation programme full of concrete actions to promote biodiversity. This year, something special is happening: the implementation programme runs from 2025 to 2027, because many of the planned activities need more time to have a real impact. Time needed for sustainable change, because biodiversity cannot be rushed. Biodiversity policy will also be revamped in the coming period to respond to current developments and there will be an even greater focus on cooperation, education and research.

Connection with surroundings

In the implementation programme (see document), in addition to work focused on the campus itself, we see activities that add value to flora and fauna outside the campus boundaries. In terms of biodiversity, we cannot behave as if we live on an island: after all, the campus is part of a larger set of biotopes. A good example is the handling of reptiles and amphibians. There is a long fence between the railway and Heijendaal campus that stops protected species, including the sand lizard. Based on a proposal by scientist Sander Turnhout, the project group, together with concerned local residents and students, and with the cooperation of Prorail, will investigate whether 'reptoducts' could provide a solution. A reptoduct is an (under) passage - in this case in the fencing and promotes the connection between the campus and the railway zone behind it.

Toad ladders

The project group also gained knowledge of so-called 'toad ladders'. This follows the situation in spring 2024, when nearly 100 amphibians were found migrating from the forest near the Berchmanianum to the overflow pond on the other side of Houtlaan. Of these animals, 27 had ended up in street and sewage gullies that they cannot get out of on their own. Nijmegen city ecologist Joep van Belkom organised a transfer campaign this spring with a group of dedicated volunteers. In the end, almost 1,000 (!) animals managed to reach the other side of Houtlaan, showing that the campus and its surroundings are a promising area for the amphibian population. Nature organisation RAVON* recommends installing toad ladders on Houtlaan and Toernooiveld within our campus. The project group is having these installed in 48 gullies. With the installation of toad stairs, the majority will now find their way out.

Non-intervention as a strategy

To promote biodiversity, much can be done on campus, such as planting trees and cutting grass with policy. What the project group is becoming increasingly aware of is the choice of deliberate non-intervention. For example, the project group is looking more critically at controlling brambles, such as recently in the forest near the Disveldpad. A few years ago, a new forest was planted there with the help of local residents. There were signs that brambles had completely overgrown this new planting. Instead, observations during a recent visit showed a predominantly positive picture. The planting is developing well and growing well above the brambles. The brambles keep the soil beneath them moister which stimulates the growth of the plantings. The project group decided to remove only the brambles along the paths and not intervene further because of possible disturbance to the flora and fauna present. The situation will be reassessed in September.

If necessary, the pruning shears

For the success of the implementation programme, the project group largely depends on the knowledge, capacity, commitment and enthusiasm of many stakeholders. The programme will therefore be implemented as much as possible in cooperation with students, scientists, maintenance parties, nature organisations, volunteers and local residents. The Radboud Biodiversity Sounding Board Group, the 'review committee' with broad representation from the campus and beyond, is an important partner. Enthusiastic members already indicated at the last meeting that, should it be necessary to control brambles in the Disveld forest, they would be willing to handle the pruning shears themselves under the guidance of our green experts!

*Creemers, R.C.M. (2025). Overzetactie voor amfibieën op de Houtlaan (Nijmegen) 2025. RAVON rapport 2025.142.)

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Organizational unit: Campus & Facilities
Theme: Sustainability