Natural age and size of Pinus sylvestris and Picea abies on a mire in the inland part of northern Sweden

The investigation was carried out on a sparsely forest covered poor fen 350 m a.s.l. in the inland pan of northern Sweden (64°32'N, 18°55'E). On the investigated mire the natural regeneration of pine Pinus sylvestris has been relatively successful from the 1920's up to the beginning of the 1970's. Natural regeneration of spruce Picea abies has taken place throughout the period 1938-1970, whereafter no establishment at all has occurred. The age and size structures of the pine and spruce stands on the mire vary in pattern according to the particular type of vegetation in which they are growing. Both the climatic amelioration during the first half of the present century and the successional stage of the mire vegetation were found to be important in regard to present-day age and size structures of the pine and spruce. Root competition and snow conditions arc probably important determinants of the size structure of pine stands in the mire environment.