Озеро Зоммен: природа, история и легенды Южной Швеции.

Sommen is a lake in the South Swedish highlands lying across the border of the provinces of Östergötland and Småland. Situated about 147 metres above mean sea level, the lake has an area of and has a maximum depth of 60 metres. Scholar Robert Norrby considered that the name Sommen originated as a noa name an unknown sacred or taboo name that the lake had.

Local mythology asserts that the lake was created by a cow called Urkon or Sommakoa. The lake basin was carved by Urkon with her hooves during an outburst of wrath; subsequently the basin was filled with water which became the lake. At present there are two commemorative raised stones at Fruhammar, the location of this purported event.

During much of the 19th and 20th century the lake was used for log driving. This activity peaked around World War I and declined as the road network around the lake improved. At present only one barge survives at the naturum Sommen museum. In 1973 log driving ceased for good.

Relative to other areas of southern Sweden, Sommen stands out for its low precipitation and low humidity. efn ua|Temperatures are given for Malexander 1961–1990. The vegetation around the lake is mostly dominated by pine and spruce forest. Broad leaf forest and open agricultural fields can also be found at some locations. In particular the southern side of the lake contains more lush vegetation and broad leaf forest than the northern side, which has more cliffs and contiguous pine forest. The rare and endangered flower Anthericum liliago can be found along the lake's rocky shores. This is one of the northernmost locales where it grows. The name Ydre, which was formerly applied to most of the area around Sommen, is interpreted to mean "place of yews". One locality in particular appears to be further associated with yews; this is Idebo along Norra Vifjärden. Red granite is a common rock around the lake and various parts are covered with till, including ground till deposited during the Ice Age. Drumlin like forms and crags are also found throughout the area around Sommen. The biogeography of various aquatic species deemed glacial relicts that are found in Sommen is likely related to a different geography during the early history of the lake. One theory claims that aquatic species were transferred from the Baltic Ice Lake through a natural lock system in connection with a temporary advance of the ice front during the Younger Dryas.

Large birds that breed in the area include fish hawk, European herring gull, heron and black throated loon. Inventories of these four birds were taken in 1974, 1980, 1994 and 2012. An inventory made in 2018 showed that during summer about 1,000 cormorants live in the lake area. As cormorants feed on fish, their population is thought to impact on the amount of fish, possibly producing an ecological disturbance. Hunting of cormorants is allowed under certain conditions from 2019 to 2023.

Twenty two species of fish are found in Sommen. Less common fishes include common roach, common bream, tench, vimba and common bleak. Populations of Sommen charr declined over the 20th century, leading to the fish being declared endangered in 1970. The implication of this difference is that Sommen charr either reach maturity later than charr in Vättern, or that they grow faster. These species are Pallasea quadrispinosa, Mysis relicta and Limnocalanus macrurus. However, the lake lacks the most common relict crustacean found in the lakes of southern Sweden, the Mysis relicta.