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FENNIA 66, N;o 4
45
cases for the greater part probably owing to the planting of spruce. The
division according to species has thus altered in a favourable sense.
The age-classes according to the forest area differ from
a normal, even distribution in the southern half of Finland, seeing
that the seedling stands are far below normal, fairly young forests
are more or less normally represented, medium-aged forests very
abundantly, and forests approaching maturity and mature forests
cover a normal area on the whole. The age-classes in the forests of
the northern part of the country differ from the former mainly in
the fact that the medium age-classes are not quite so abundant,
tut the old age-classes far exceed the normal quantity.
The total volume of the growing stock amounts to 1 560
million m3 including bark. The mean volume per ha of forest land is
62.8 m3 and the mean volume per hectare of productive forest land
74.8 m3. The results of the survey in 1922—23 were 1 620 million m3
and 64.3 m3 per hectare of forest land and 75.6 m 3 per hectare of
productive forest land. The results of the two surveys are, however, not
directly comparable. If they are made comparable, it is seen that the
volume of the growing stock is now 28 million m3 (1.8 per cent) less
and per hectare of forest land 0.3 m3 less than in 1922—23. This
difference corresponds on the whole to the reduction of the forest area
already mentioned. It should be noted that it is less than the
uncertainty indicated by the calculation of probability, so that it need
not necessarily be real.
The total volume referred to above consists of the growing, living
stock. In addition the forests contain dry, dead trees that are still
standing, and windfalls, i.e. trees blown down, but free from rot.
Their combined volume is 56 million m3, of which about 70 per cent
are in North Finland, 19 per cent in East Finland and only 11 per cent
in all in the forests of West Finland and Ostrobothnia. The volume of
dry trees is about 54 million and of the windfalls about 2 million m3.
The total volume of the growing stock is divided as follows between
the different species of trees: pine 706.o million m3 or 45.3
per cent, spruce 502.8 million m3 or 32.2 per cent, birch 295.3 million
m3 or 18.9 per cent, aspen 29.3 million m3 or 1.9 per cent and alder
26.6 million m3 or 1.7 per cent. Since 1922—23 the volume of pine
has decreased by 71.3 million m3, possibly to a considerable extent
owing to much cutting of over-mature forests. The volume of spruce
has increased by 22.3 million m3. In North Finland, where the
conditions for the yield of spruce are poorer owing to the barren nature
of the soil in general than in the southern half of the country, the
volume of spruce has decreased by 19.8 million m3, but in the southern
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