Seed yield of Downy birch (Betula pubescens) at Kilpisjärvi, NW Finland, 1979-2007 (Northern LTSER)

The catkin data originate from 15 permanent research stands of the Finnish Forest Research Institute (FFRI). This dataset includes results of the most northern stand Kilpisjärvi. Downy birch trees were observed during the study period 1979–2007. Observations were made repeatedly from the same tree individuals, using a standardised method. The numbers of male catkins were visually estimated with binoculars in autumn or winter, and the trees were divided into six groups according to the abundance of catkins.