Conditions of the occurrence of Anemone sylvestris in a kettle hole in north-eastern Poland

The research, in 2004, was focused on the whole population of Anemone sylvestris (Snowdrop Windflower) present in the area of a kettle hole (0.8 km2) in north-eastern Poland (52°50’00’’N; 23°11’20’’E). The location of 56 clumps of generative specimens was surveyed. They numbered from several to approx. 1500 specimens. The number of generative specimens in this population exceeded 10 000. On account of this, it is a unique stand of A. sylvestris in Poland. The relationship between the occurrence of the Snowdrop Windflower and the presence of kame hills and ridges has been proven. Low slopes of kame with an inclination of 10-20o, and a north-eastern or eastern exposition has been found as the local ecological optimum for this species. Research carried out in 1970-2001 on 5 permanent plots (25 m2 each) has shown that: 1) Anemone sylvestris is an essential element of xerothermic grasslands of the order Festucetalia valesiacae; 2) the species suddenly withdraws from the parts of land on which woody species have already reached the shrub layer; 3) the greatest danger for the population of A. sylvestris in this area is the process of secondary succession initiated by the discontinuation of grazing on the kame hills.