The grass genus Aira in Finland

Kirjoittajat

• Carl-Adam Hæggström
• Ralf Carlsson
• Eeva Hæggström

Abstrakti

Three species of the genus Aira, viz. A. praecox, A. caryophyllea and A. elegantissima, have been found in Finland. The geographical range of each species is outlined. Whereas A. praecox has been known since 1912 in the Åland Islands, A. caryophyllea was found as a new species for Finland on the mainland of Kumlinge, Åland Islands, in 2008. A. elegantissima has been found as an introduced plant (weed or sown as an ornamental grass) in five localities in different parts of southern Finland between 1868 and 1985. All seven known localities with their separate stands of A. praecox were studied in detail in the Åland Islands in 2009. Of these localities, one was found in 2005 and two in 2009. The accompanying vascular plants were noted and their calcium dependence was assessed according to previous studies. The accompanying species comprised 113 field layer taxa, most of them common in the Åland Islands. The majority of the accompanying taxa belong to the calcium-neutral group. However, 27 calciphilic species were found, about 24 % of all the accompanying taxa. The amount of calciphilic species was compared to previous studies in Åland. Soil samples, chiefly fine sand, from all but one of the seven localities were analysed for pH, exchangeable Ca++, Mg++, K+ and PO4-. Further, NO3- and NH4+ were determined and soluble nitrogen was calculated from values on NO3- and NH4+. The pH values of the soil samples were mostly rather low for the Åland Islands. The concentrations of exchangeable Ca2+, K+, Mg2+, PO4- and soluble N were also mostly rather low. A. praecox often grows by bathing beaches, and thus a possible way of dispersal is by bathers and campers, e.g. with blankets. The locality in Kumlinge seems to be on ballast brought ashore from a sailing ship long ago. Although A. praecox has disappeared in some stands in localities 1 and 2 in Eckerö, much larger stands and three additional localities are known today. However, A. caryophyllea may be endangered, as it is hitherto known in one locality only and the number of specimens was about 50 in 2009.