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Most logging residue is still left in forests |
It has been calculated that every year, 14 million cubic metres of logging residue is produced in regeneration fellings in Finland. In 2005, for example, less than 15 percent of this was collected for use. Moreover, some 15 million stumps are produced in regeneration fellings annually and of them less than one percent was collected in 2005.
The theoretical maximum of logging residue production is considered to be about 25 million cubic meters. Some 15 million cubic meters annually could be gathered for use in a technically and economically feasibly.
Most of the logging residue is produced in regeneration fellings of spruce; the volume of logging residue produced is 20–30 percent of the volume of roundwood harvested. In Southern Finland this means 50–80 solid cubic metres of logging residue per hectare. This would generate 125–200 cubic metres of forest chips.
The greater part, or about 60 percent, of forest chips are made from logging residue: from the branches and crowns of trees felled. The rest is made from stems, stumps and stubs, stout stems and debranched stems. Estimates are that over 60 percent of the forest chips used originate from regeneration fellings, ten percent from energy wood thinnings and the rest from thinnings.
Energy wood thinnings are carried out in young forests which are too dense and require thinning due to forestry reasons. In forests of this kind, the stem diameter is too small for use as pulp wood, and the thinnings are used for energy.
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