Abstract

By means of daily temperature data records of two research stations in North European middle and north boreal regions (Svartberget in Northern Sweden resp. Oulanka in Northern Finland) from 1981 to 2005 the changes in time spans of the five ecological seasons (snow winter, pre-spring with snow melting, snow-free spring, climatic growing season, snow-free autumn) are presented. A remarkable increase in the duration of the growing season and an intense decline in the duration of the snow winter can be stated. The transitional seasons show slight variations, too, but not as important as the two main seasons.