- Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
The aim of this work was to determine how early management activities in young, dense pine forests affect tree and stand characteristics and profitability and to assess the future potential for tree biomass harvesting and use. In this respect, the long-term effects of corridor pre-commercial thinning (PCT) and thinning on growth and yield were investigated in 11 Scots pine (Pinus sylvestris L.) stands (I). The potential for applying goal-oriented regimes at the PCT-stage was studied in a 20 year old direct seeded lodgepole pine (Pinus contorta) stand (II). The influence of management regime on fibre length (III) and profitability (IV) in Scots pine stands was analysed after destructive sampling and using simulations, respectively. The potential of future end-uses of the tree biomass were investigated through a survey and by analysing electricity prices with respect to different tree/wood assortments (V). The form and intensity of PCT influenced the mean diameter at breast height (DBH) and individual tree growth but had little impact on the mean DBH of the largest future crop trees. Stand management regimes with higher stem numbers than conventional options produced substantially larger amounts of stemwood and tree biomass (I, II) and increased the proportion of mature wood in stems that might be suitable for harvest in late silvicultural operations. High intensity early thinning of dense stands limited the proportion of juvenile wood when the stand matured (III). Corridor PCT/thinning did not significantly reduce volume growth or standing volume compared to selective treatments, and may be useful for obtaining biomass from dense stands. Stemwood production was relatively independent of the corridor area, indicating a certain amount of flexibility with respect to harvest intensity in early corridor thinning (I). Boom-corridor thinning at a mean height of 8-9 m instead of conventional PCT generally improved the land expectation value, demonstrating the economic potential of early biomass removal. The economic break-even harvest yield amounted to about 32-44 oven dry tonnes/ha with corridor areas of 40-50% (IV). The value of tree biomass was expected to increase over ten years, especially for raw materials refined into products such as transportation fuels, specialty celluloses, plastics, solid fuels, or chemicals (V). In conclusion, young stand management activities provide forest owners with diverse opportunities to increase biomass yields and uses, manipulate stand and future crop tree characteristics, and increase profitability. New end-uses of tree biomass may influence the profitability of early biomass thinning and the silvicultural regimes of the future.
Biomass production; corridor thinning; profitability; fibre length; Scots pine; lodgepole pine
Acta Universitatis Agriculturae Sueciae
2013, number: 2013:90
Publisher: Institutionen för skogliga biomaterial och teknologi, Sveriges lantbruksuniversitet