Natural regeneration and management of birch

This thesis offers guidance for those who want to naturally establish, maintain and manage birch in monocultures and mixed stands. Silver and downy birch are the most common broadleaf tree species in northern Europe. In Sweden, the two species together make up approximately 12% of the standing forest volume. This thesis presents results from four studies (papers I - IV), with the aim to increase the level of knowledge about establishment and regeneration of birch, management of naturally regenerated birch in pure and mixed stands, and the distribution of birch over Sweden. The studies were based on experimental data from field trials, survey data from practical forestry, Swedish national forest inventory data and predictive modelling. On dry soil, mechanical site preparation is necessary in order to get a successful regeneration of birch; in wet soil moisture conditions, natural regeneration of birch will appear without effort. It is possible to manage the birch regeneration success if the soil scarification is adapted to the soil moisture conditions (paper I). The proportion of silver and downy birch varied in Sweden’s young forests, and the temperature sum explained most of the variation (paper II). In dense, naturally regenerated stands of birch and Norway spruce, pre-commercial thinning (PCT) had a significant impact on the development of the future stand, and there are several profitable management strategies for the owner of this type of stand (paper III). The proportion of birch tends to decrease after canopy closure in mixtures of Norway spruce with stand age in southern Sweden, regardless of thinning (paper IV). Active forest management is key, in order to maintain the proportion of birch over the full rotation period. In conclusion, this thesis offers knowledge that can contribute to a more varied forestry, and forestry with a greater element of broadleaf trees.