Early thinning of energy wood in dense mixtures of Norway spruce and birch in Northern Sweden

• Naturally regenerated silver birch (Betula pendula) and downy birch (Betula pubescens) commonly appears in mixtures with conifers and constitutes a considerable part of the growing stock of young forests in Sweden. The proportion of birch is traditionally heavily reduced during pre-commercial thinning to promote the development of conifers. In dense mixtures where no pre-commercial thinning has been carried out and where the average tree dimension is small, thinning of energy wood might be an alternative to conventional pulp wood thinning. Moreover, the goals for future management might need to be revised due to a pronounced interspecific competition. An experiment was established in Northern Sweden to study the potential of energy wood thinning in unthinned mixtures of naturally regenerated Norway spruce (Picea abies) and birch. The stem number before thinning was 13800 and 3200 stems ha-1 and the dominant height was 15 and 7.5 m for birch and spruce, respectively. The treatments included an unthinned control and three thinning strategies resulting in pure plots of spruce and birch and a mixture of spruce and birch, respectively. Within the thinned plots the stem number for each species was kept constant where they appeared. The same number of spruce and birch trees was also marked and followed within the unthinned plots in order to study the influence of thinning on the development of main stems. Whole trees were harvested and a strip road was established in the centre of each plot. The presentation focuses on the early development and survival following the alternative courses of action and on the comparison of extractable volumes between energy wood thinning and conventional thinning of pulp wood. Influence of strip roads on the development of the adjacent trees in young stands will also be discussed.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Skogsvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Forest Science (hsv//eng)

Publikations- och innehållstyp

vet (ämneskategori)

kon (ämneskategori)