Renovation and extension of Steinlinse, Riedwiese Harberen

To the north of Zurich, the Furttal valley stretches from Regensdorf to Würenlos in an east-west direction. Here, between intensively used agricultural land, which is used for vegetable and herb production, among other things, there are no fewer than 24 cantonal nature reserves in the Zurich communities of Boppelsen, Buchs, Dällikon, Dänikon and Otelfingen. These nature reserves are characterized by a strong structure and high diversity. For example, reed beds that have been waterlogged by slopes are located directly next to dry, lean meadows and sparse mixed forests.

The approximately 2.5 hectare area "Harberen West" lies on the border of the municipalities of Otelfingen and Boppelsen. The sloped meadow, which is wet in various places - but also has dry, permeable areas - is crossed by numerous small, species-rich trees, which also include some huge old oaks. There is also a small body of water. This structural diversity means there are countless cover and hiding places for small animals, and the many different microclimates mean that the floristic diversity and thus the food supply is extremely diverse. In 2019, nature net operations in the area observed not only countless unidentified insect species, but also the brown hare, fox, sand lizard, fire salamander, checkered butterfly ( Melanargia galathea ) and the caterpillar of the willow borer ( Cossus cossus ).

On the north-western edge of the area there is a large stone lens, which has been created over the years from stones and other unwanted things from the nearby, intensively used agricultural land. Such a stone lens is actually an excellent small structure or an excellent habitat for sand lizards, for example. They can sun themselves on it in the warm months and overwinter in the deep cracks between the stones. Unfortunately, due to its age, the stone lens is heavily saturated with humus and is also completely overgrown with blackberries and other vegetation. It also served as a dumping site for waste. This means that the stone lens loses its ecological value.

The Nature Network's civil servants were commissioned to renovate and upgrade the stone lens. To protect the existing fauna, only half of the lens was renovated - the second part of the renovation will take place in 2020/21.

In order for the civil servants to even get to the stone lens, they first had to cut back the vegetation with brush cutters and remove it with rakes. They could then use pickaxes, cross axes, shovels, spades and by hand to dig up stones layer by layer, remove rootstocks from blackberries, etc. and get rid of rubbish. Large stones were transported by up to four civil servants using special stone tongs. For the new stone lens, a few deeper places were dug into the ground. Small animals can later overwinter in these frost-free places. The existing stones, as well as wood material obtained from nearby hedge maintenance, were now layered in the various trenches. Small chambers were repeatedly created as overwintering places for small animals such as slowworms or hedgehogs, as well as the sand lizards and fire salamanders already observed in the area, and small entrances to the chambers were left open, safe from predators. The stone lens was stacked until all the available stone and wood material had been used.

In just two days, the Harberen West reed bed area was expanded to include another ecologically valuable small structure with many niches for many different species. We look forward to more exciting observations and to the second part!