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

The human direct and indirect impacts over millennia have changed the
tree species composition of forests, particularly in the boreonemoral and
nemoral zones where species diverse deciduous or mixed forests were
gradually replaced by forests dominated by beech and conifers in Denmark
and conifers in Sweden (e.g., Bradshaw & Holmqvist 1999, Björse
& Bradshaw 1998). The expansion of agricultural activities to feed an
increasing population and inadequate consideration of forest resources
probably resulted in the smallest forest area since the last ice age in the
late 1700s in Denmark and about 100 years later in Finland, Norway and
Sweden (Bradshaw 2004).
In spite of the accelerated forest harvesting of boreal forests during
the late 1800s, considerable forest areas in the north and interior were
probably not very heavily influenced by active forestry around 1900
(Östlund 2004). Nevertheless, the total growing stock of Fennoscandian
forests at this period may have been at its lowest since forests were established
after the last ice age. This was due both to the reduction of the
forest area in order to increase agricultural production, as well the extractive
nature of the harvesting of the forest resources, where especially
the largest and most valuable trees were harvested first without much
effort invested in developing new growing stock.
Results from the earliest forest inventories in Finland, Norway and
Sweden, as well as various studies of forest history (e.g., Östlund et al.
1997, Östlund 2004, Storaunet et al. 2005, Hellberg et al. 2009, Lie et al.
2011), give an impression of what these forests were like around 1900:
The total growing stock was quite low, maybe as low as 20% of the
original forest growing stock before the expansion of agriculture
from the Bronze Age onwards and the increasing timber harvesting
over the last 500 years. In Norway, the forest growing stock today is
more than doubled since the early 1900s, 2 and in Finland and
Sweden the equivalent increase is about 70% (Metla 2011) and 85%
(SLU 2011), respectively. However, locally, the growing stock may
have been comparable to current levels (Lie et al. 2011).
The forest structure was quite open, multi-layered, with an established
canopy over most areas, and with a varied age structure and poorlydefined
stand structure.
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2 http://www.skogoglandskap.no/nyheter/2007/1192537469.38
Biodiversity, carbon storage and dynamics old northern forests 35