Biodiversity, carbon storage and dynamics of old northern ... - BPAN.fi

agement, and final cutting of the whole stand. This management model
was rapidly applied on a large scale, particularly in Finland and Sweden,
somewhat less consistently in Norway, and in Denmark mainly in
the coniferous forests. Since the 1990s some of these silvicultural
measures have been more strictly regulated than in previous decades,
e.g., use of pesticides, forest ploughing, ditching, and planting of exotic
species. In Denmark, nature-based forest management has been introduced
since 1990, with more use of natural regeneration, less ditching,
and more use of native species, although planting of exotic welladapted
species and provenances is also used.
The basic idea behind the stand-based management model is to promote
rapid growth and a large harvestable stock of the preferred tree
species. However, if consistently applied over the whole forest area, as
originally envisaged, it would also lead to removal of non-preferred tree
species, trees without adequate growth potential, trees older than the
optimal cutting age (70–120 years in most boreal forests), and a strong
reduction in the amount of dead wood (coarse woody debris in particular).
Also, the structure of the forest landscape is more schematic, with
high contrast between clear-cuts or young forest stands and stands of
dense mature or over-mature forest.
Over the last few decades, two opposing processes have influenced
forest management. One is a trend towards ever more effective forest
management, especially of the most productive forests, and an intensification
of harvesting, as seen in the increasing interest in whole-tree
harvesting for bioenergy, including stump removal. The other involves
incorporation of a range of environmental measures to ensure more
sustainable forestry for biodiversity, recreation and other social goods,
resulting in retention of some forest resources of importance for biodiversity,
such as key biotopes, buffer zones along mires and water bodies,
dead wood etc. In addition, forest areas of low productivity or otherwise
marginal economic potential have to some extent not been
managed or harvested. In Norway in particular, less than 50% of the
annual increment in the growing stock is currently harvested. 3 Compared
to forest conditions of about 100 years ago, current boreal forests
have far higher growing stocks. During recent decades, some key
resources for biodiversity, such as dead wood, trees older than 120
years, and deciduous trees, have received special attention. However,
growing stocks (and hence carbon stocks) are probably lower than
under natural forest dynamics where old forest would tend to dominate
(Kuuluvainen 2009). Also, forest structures and resources of particular
significance for biodiversity, such as forest older than 160
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3 http://www.ssb.no/emner/10/04/20/skog/
Biodiversity, carbon storage and dynamics old northern forests 37