Dvärgagen återupptäckt i Sverige efter 63 år som utgången.

• Cyperus fuscus was rediscovered at Lake Vombsjön in Skåne, southernmost Sweden, in 2013. The species occurred there between 1945 and 1950, which was the latest Swedish record except for a casual occurrence in a plant nursery. The comeback was spectacular with 2770 individuals counted along 4.7 km of the shore. In 2013, the water level was exceptionally low for technical reasons, with up to 100 m of the sandy shore exposed during the entire vegetation period, i.e. the same conditions as during the late 1940’s. Later, the lake became an important source of drinking water, and the regulated maximum water level was increased with more than one metro. The coming years will show whether the species regularly occurs at low frequency at the lake, or if it is dependent on rare years with low water to survive.

• Cyperus fuscus was thought to be extinct in Sweden until it was rediscovered at Lake Vombsjön, Skåne, after 63 years in 2013. The species also occurred at the lake 2014—2021, but in very variable numbers. The variation depended largely on the water level during late summer. Favourable conditions in form of low levels in late summer have also occurred prior to 2013, though less frequently than in recent years. It is concluded that 2013 most likely was not the first year since 1950 that Cyperus fuscus occurred at Lake Vombsjön. Data are also presented from Lake Sövdesjön , where the species was discovered for the first time in 2019 and also occurred in 2020 and 2021. Here, the numbers are lower than at Lake Vombsjön, but the occurrence seems stable.

Ämnesord

NATURVETENSKAP  -- Biologi -- Botanik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Botany (hsv//eng)

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