Alvar lake

An Alvarsee is a shallow still water typical of the Alvar landscape . Alvar lakes exist, for example, in Stora Alvaret on the Swedish Baltic island of Öland .

In an Alvar there is only a very thin layer of soil , under which there is a layer of rock. This means that rainwater quickly collects in existing sinks. While the Vätar, which is also typical for Alvare, periodically dry out completely, the water in the Alvar lakes remains permanently due to the size and depth of the respective depression, apart from cases of extreme drought.

The extent of the Alvarsee is subject to fluctuations depending on the seasonal water resources, with water typically remaining in the middle of the lake even in dry periods. This characteristic means that there are good conditions for permanent vegetation to be established, especially in the middle. In this way, a green zone of bog and sea plants is created there, which is surrounded by open water. The center island tends in the course of silting expand. Alvar lakes become swampy areas as they become silted up .

Alvar lakes are known for their abundance of birds. Well-known Alvar lakes are Möckelmossen , Dröstorps mosse and Stormaren on Öland.

literature

• Staffan Rodebrand, Moore auf Öland , Lansstyrelsen i Kalmar län, ISBN 91-974576-9-8 , page 12 f.