Species immigration, extinction and turnover of vascular plants in boreal lakes

Dictated by limited resource availability for land acquisition, a central question in conservation biology is the ability of areas of different size to maintain species diversity. The selected reserves should not only be species rich at the moment, but should also maintain species diversity in the long run. We used two sets of data on vascular plant species in boreal lakes collected in 1933-1934 and 1996 to test the relationships between lake area and the extinction, immigration and turnover rates of the species. Moreover, we investigated, whether the number of species in 1933-34 or water connection between lakeswas related to extinction, immigration and turnover rates of species. We found that lake area or shoreline length was not correlated withimmigration, extinction or turnover rate. The original number of species was positively related to the number of species extinctions and to the absolute turnover rate in the lakes, which indicates that species richness does not create stability in these communities. Species number was not correlated with immigration rate. Upstream water connections in the lakes did not affect immigration, extinction or turnover rates. We conclude that because lake area is not related to turnover rate, also small areas can be valuable for species conservation. [ABSTRACT FROM AUTHOR]