Seventy-year changes in tree species composition and tree ages in state-owned forests in Latvia

Abstract

During the last 100 years, forest management in Latvia has gradually become more and more focused on industrial logging, which can be expected to have affected the tree species composition and age distribution across the landscape. These changes need to be considered in forest management and conservation of biological diversity. The aim of the study was to use forest records to reconstruct the tree species composition and age distribution in the North Vidzeme Biosphere Reserve in northern Latvia for the period, 1929–1941. These data were compared to a data-set from 2008, to determine the changes that transpired during a period of intensification of forest management. The silvicultural methods in the 1920–1941 period were based mostly on natural regeneration of logged stands. This led to succession to birch on harvested spruce stands and can explain the relatively large cover of mature birch stands today. After 1960, forest management was directed on conifer monocultures, and thus spruce stands today predominantly have age <50 years. An age class >150 years is almost absent for all species, and conservation should be directed to adding a portion of old forests to the protection network, and in maintaining the spatial continuity of overmature deciduous stands.