Environmental Engineering Reference
In-Depth Information
Fig. 10.2
Tree species composition
according to PNV (left-hand
diagram) and recent vegetation
(right-hand diagram) for Bavaria.
Diagrams are based on data from
Walentowski and Gulder (2001).
Deciduous trees: Fs,
Fagus
sylvatica
; Qrp,
Quercus robur
and
Quercus petraea
; Ap,
Acer
pseudoplatanus
; Cb,
Carpinus
betulus
; Fe,
Fraxinus excelsior
.
Coniferous trees: Pa,
Picea
abies
; Aa,
Abies alba
; Ps,
Pinus
sylvestris
; Ld,
Larix decidua
;
Pseudo,
Pseudotsuga menziesii
.
Misc., miscellaneous.
PNV
Recent
Pseudo
Ld
Pseudo
Ps
Misc.
Ld
Misc.
Aa
Fs
Qrp
Ap
Cb
Fe
Ps
Pa
Fe
Cb
Aa
Ap
Qrp
Fs
Pa
10.2.2 300 years of forest management
The economic value of today's managed pine
and spruce forests is much higher than that of the
devastated forests 300 years ago, and a lot of char-
acteristics, like canopy closure, stand structure and
microclimate, are closer to the natural forest stands
than during that time. Nevertheless, soil quality is
changing under the influence of decomposing needle
material: decomposing needles force soil acidification,
thus reducing the biological activity of the soil. As a
consequence essential nutrients such as Ca
2+
, Mg
2+
and
K
+
are stored in the upper organic soil layer (see sec-
tion 10.5.2; Wolff & Riek 1997), no longer being avail-
able for plant growth. Additionally the storms Vivian
and Wiebke in February 1990, throwing down mainly
pine and spruce trees (König
et al.
1995), showed that
the recent forest situation should be improved. A
conversion from needle-tree dominance to mixed
forests is a major goal of forestry for the near future
in central Europe.
Today the concept of forest sustainability includes
much more than the production of the valuable,
regenerating resource timber; it includes also protec-
tion of drinking-water resources, protection against
soil erosion and noise, use of forests as an element
in landscape architecture and a place for recreation
and inspiration of humans, conservation of genetic
resources and carriers of natural diversity (genotypes,
species and ecosystems). The capacity of new estab-
lished forests to store CO
2
has been given high
priority in the discussion of global climate change; CO
2
Although the first attempts at forest restoration were
carried out in the 14th century (the oldest managed
forest of the world is the Nürnberger Reichswald;
Sperber 1968), forest utilization meant forest plunder-
ing for several centuries. It was only in the early 18th
century that Hans Carl von Carlowitz (1645 -1714),
member of the administration of the mining industry
in Freiberg/Saxony and responsible for timber produc-
tion, realized that only with a strong forest manage-
ment could timber production be maintained for a longer
time. In his topic
Sylvicultura oeconomica
, published
in 1713 (the first textbook on silviculture!) he wrote
that 'We have to make every effort in science and
forest practice to find out methods for protection and
production of timber in a sense that a permanent
sustainable utilization can be realized' (translated). This
is the first time that sustainability is presented
explicitly in a textbook. The idea developed quickly,
and since the middle of the 18th century regulated
forest management has been introduced into many parts
of Europe. Pine and spruce produce a lot of seeds, and
the seeds are easy to harvest, transport and handle,
and therefore pine and spruce were used intensively
in forest restoration after the phase of degradation.
This is the reason that today these two tree species
make up about three quarters of the temperate Euro-
pean forests, while the natural potential is for about
three quarters deciduous trees, mainly beech (Fig. 10.2).
