Clearing and maintenance of Degenried pond
Realized:
2019
performed by:
Naturnetz Mittelland
The Degenriedweiher pond in Zurich Hirslanden is an important spawning water for common toads (Bufo bufo), grass frogs (Rana temporaria) and alpine newts (Ichthyosaura alpestris). In spring, a mass migration of the animals towards the pond takes place. In 2012, an amphibian guidance system was installed over a total length of approx. 495 m so that the animals do not have to take the dangerous route over Degenriedstrasse during the amphibian migration, allowing them to cross the road safely underground. Now only individual animals die on the road - the majority of the amphibians make it through the guidance system to the pond unharmed. Regular success checks during the amphibian migration (the Nature Network will be carrying out monitoring again in spring 2020 in collaboration with Grün Stadt Zürich) confirm the protective guiding effect.
The Degenriedweiher pond itself is maintained at regular intervals (every 5-8 years) so that it can maintain its function as a spawning pond in the long term. The main aim of the maintenance is to allow more light to reach the pond surface and to remove as much humus/nutrients from the pond as possible. This is necessary because the pond is becoming overgrown due to the vegetation on its banks and is slowly becoming silted up due to the constant input of nutrients.
In November 2019, the volunteers from the nature network went to Degenried for three days of work, armed with fishing boots and a chainsaw. They cut back the riverside trees and some willows on the islands (to the stump), with the fast-growing species (alder, hazel) in particular having to be pushed back heavily. The volunteers spared slow-growing, rather rare species such as hawthorn and spindle tree. They felled some larger riverside trees that took too much light from the pond. They mowed the partially dense blackberry population around the pond as well as a smaller reed area and picked blackberries in places. They removed the few neophytes (buddleia, locust). And finally, they removed algae, leaves, dead wood and other humus from the pond with aluminum / hay rakes and pitchforks. Most of the green waste that accrued was left behind in the nearby forest, e.g. in the form of dead wood and old grass piles as a small structure.
After this exciting work, we are excited to see how many amphibians will manage to migrate through the guidance system into the pond this spring!