Main lines of forest management in Finland’s
coniferous forest zone
 |
The Nordic cut-to-length (CTL) felling system and machinery is
suited also to the conditions of first thinning without causing
damages to the remaining trees on the site. |
The aim of forest management is multifunctional: to safeguard
the production of high-quality roundwood, the biological diversity
of forests and the potential for the multiple functions
and services derived from forests. Because forest owners have
widely differing needs and expectations, the range of forestry
options has been broadened in recent years, and further development
is ongoing.
The basic unit for forest management in Finland is the stand.
Forest stands are classified according to their naturally occurring
plant communities, based on a forest site type classification developed
by botanist A.K. Cajander in the early 20th century. The surface vegetation at each individual site indicates the properties
of the site and also the growth potential of trees. There are
six main site types in southern Finland, and management and
harvesting are directed according to their properties. The average
size of managed stands in southern Finland is about 1.2
hectares, which is about the same as the average in Germany,
Austria and France.
The big picture in landscape terms is fragmented and mosaiclike
due to differences between individual stands in tree species
composition, age structure and the timings of regeneration and
management procedures. The principal silvicultural requirement
is that forest regeneration after felling must be ensured. This is
often difficult to achieve without soil preparation because natural
forest fires are prevented; the special characteristics of the
tree species, other flora and climate of the boreal zone lead to
the formation of a layer of humus over mineral soil, inhibiting
germination.
Stand-based forest management in Finland’s boreal zone typically
involves managing even-aged stands. Management is clearly
divided into two phases, growth and regeneration. Depending on
the tree species, geographical location and site characteristics,
the recommended growth period varies from 50 to 120 years.
At special sites, such as landscape areas and forest parks, cultural
sites or forests dedicated for recreational use, uneven-aged
management systems are also used. In uneven-aged management,
different growth stages are concurrent, and stands are
managed with single-tree selection.
In the growth phase, seedling stands are managed by cleaning
and thinning. Young and advanced thinning stands are managed
by intermediate fellings, which are carried out 1–3 times
during the growth cycle of the stand. Each time, 25% to 30%
of the then current growing stock in the stand is removed. The
purpose of intermediate fellings is to direct the growth of the
stand in favour of the best trees, to encourage their growth
and thereby to produce harvesting income already prior to regeneration
felling.
In the regeneration phase involving natural regeneration, seed or
shelterwood trees are left standing to seed the site. Sometimes
natural seeding may take place by trees on the forest edge surrounding
the regeneration area, or several small regeneration
clearings may be opened up by local felling in the stand. Artificial
regeneration by seeding or planting is preceded by final
felling that completely removes the growing stock. The success
of regeneration is ensured by clearing the site and exposing
mineral soil with mechanical soil preparation prior to regeneration,
and ensuring that grasses will not endanger the early
development of seedlings.
The goal is to create a fully productive stand with a suitable species
composition in a reasonable period of time. The majority
of Finland’s current forests have regenerated naturally; about
35% are planted or artificially seeded. However, even artificially
regenerated stands have great numbers of naturally regenerated
trees as well.
 |
| Natural regeneration of pine is most suitable in sites where the humus layer over mineral soils and surface vegetation does not prevent
germination and later development of saplings. |
Biological diversity is promoted in fellings and other silvicultural
measures by leaving dead, decayed and living retention
trees in the forest and by managing valuable habitats in a way
to preserve their natural characteristics. A mosaic-like variation
in forest types at the landscape levels promotes biological diversity
by creating habitats of different ages and at different
stages of development.
Trees are for the most part harvested using the Nordic cut-tolength
system (CTL): logs are debranched and cut to appropriate
length on site, according to their use. Branches and crowns are
left in the forest to maintain an even nutrient cycle. There is a
new trend to harvest branches and crowns in spruce stand fellings
and in thinnings of young pine stands and of broadleaved
stands to be used as fuel. The CTL system of cutting is particularly
suited to conditions in Finland, as the land is fairly level.
Fellings are carried out all year round to ensure a steady flow
of wood, but mostly in winter, when the ground is frozen and
covered by snow to minimise any detrimental effects of felling
on the soil and the trees left standing.
Links
|
