Lake Türlersee & Region: A unique cultural and natural landscape

The nature network has been working for many years on behalf of the Canton of Zurich and the Eco Office for Nature Conservation & Species Promotion (Samuel Erzinger) in the Hedingen, Affoltern a. Albis and Aeugst region. The Türlersee and its surroundings are a faunal and floral hotspot. The lake is located south of the Uetliberg not far from the city of Zurich and is a popular tourist destination. It was formed around 10,000 years ago at the end of the last ice age. Large masses of rock from the Albis chain dissolved and dammed the Reppisch. At the same time, the retreat of the Linth glacier created an enchanting natural landscape, which has been preserved in many places to this day thanks to targeted protection measures. The shore areas, fens and slope marshes are home to a remarkable floral and faunal diversity. Rare butterflies and rare dragonflies still fly here, among other things. The region is also home to various amphibian spawning areas. In addition to the more common species, there is also an occurrence of the palmate newt ( Lissotriton helveticus ). The region also has a lot to offer in terms of flora. Over 20 orchid species and other rare plant species have already been registered here.

Due to the nutrient input from the air (nitrogen oxides from combustion engines) and from agriculture, the fens are in danger of becoming overgrown with reeds and bushes. This means that less competitive plant species (including orchids) are in danger of disappearing. In several areas directly on Lake Türlersee (Hexengraben, Seematte) and on the south-facing slopes of the Albis chain (protected areas: Waldriedli & am Berg) as well as in Affoltern a. Albis (Bisliker & Wängi), the nature network is carrying out an early mowing of the reeds in cooperation with community service workers. The mowing is carried out with a motorized hedge trimmer in June, and dense areas are mown with a scythe mower. With high mowing, the reeds are selectively mown above the remaining vegetation, which is usually shorter. "High mowing" is a common method in nature conservation to weaken the reeds and promote the remaining vegetation (including orchids). Although reeds are ecologically extremely valuable in the shoreline area (land/water) and must be protected, if they spread to the fens, this can lead to a decrease in biodiversity, which is why we try to combat the reeds in the fens every year. The cuttings are collected and disposed of. In addition to "reed growth/siltation", "bush growth" is also an issue in our fens. In the 19th century, groundwater levels were artificially lowered in many places. As a result, many fens are drying out and woody plants are growing that would not naturally grow. "Bush growth" is displacing rare and light-loving plant species. To counteract this process, the Nature Network has removed woody plants from a fen (Bisliker, Affoltern a. Albis) in addition to mowing the reeds. In addition to a number of orchid species, sundew ( Drosera rotundifolia ) - a carnivorous plant - is also found here.

The south-facing, extensively managed steep pastures (Breiten & Türlerrain) with their curved forest bays and the transitions between open land and sparse forest offer numerous animal species a suitable habitat. As part of extensive monitoring, over 14 grasshoppers and over 34 butterfly species were registered here (J. Landolt). In particular, the yellow-ringed butterfly ( Lopinga achine ) and the wood devil ( Erebia aetiops ) are two species that have almost completely disappeared from the canton of Zurich, but still occur in this region. Due to the great diversity of insects, the red-backed shrike ( Lanius collurio ) also breeds in this area and this year (2023) a singing cirl bunting ( Emberiza cirlus ) was observed for the first time. Both bird species prefer to occur in extensively managed cultural landscapes and have disappeared in many places in the canton of Zurich. The sand lizard ( Lacerta agilis ) also feels at home on the pasture. Regular extensive grazing is needed to ensure that this faunal-valuable habitat with the character of a semi-open cultural landscape is preserved. In recent years, "Luing cattle" have been used for grazing. In the next few years, mules could be added. The nature network was responsible for the fine maintenance of the areas. In autumn, the "blackberry patches" on the pastures were mown and some blackthorn bushes were cut down so that the semi-open character with thorn bushes and open land was preserved.

In the Jonental (Affoltern am Albis) the Mühliweiher pond is located next to the stream and the edge of the forest. This pond was in danger of silting up due to the very heavy plant growth. For this reason, the nature network reopened the pond during the dormant period in winter. In this context, some "plant clumps" were dug up so that open water areas once again predominated. We hope that the pond will be used as a spawning ground for amphibians, among other things. The location of the pond on the edge of the forest seems to be ideal, especially for the common frog ( Rana temporaria ) and common toad ( Bufo bufo ), which are likely to overwinter in the forest.

Working directly on Lake Türlersee was a privilege and a welcome change from other activities. In addition to their work, our community service workers also had the opportunity to study life in these species-rich protected areas. In addition to a number of orchids - including marsh maidenhair orchid ( Epipactis gigantea ) and bee orchid ( Ophrys apifera ) - they discovered a number of interesting dragonflies, butterflies, birds and reptiles. During the lunch break in the summer, the lake was an inviting place to have a barbecue at the adjacent bathing area. The landscape and its flora and fauna are unique in this region and motivation enough to continue protecting these beautiful natural pearls. We are looking forward to the further days of work next year.