Environmental Engineering Reference
In-Depth Information
are therefore rather high (see in A. Fischer 1998).
Mycorrhizae are also fed upon by several small insect
species living in the soil, for example the order
Protura (Apterygota). The dead wood itself is the
major carrier and promoter of biological diversity in
unmanaged and managed forests.
Altogether, it becomes clear that wind throw
means not only damage but also a chance.
Table 10.3
Areas that have been reforested with the
aid of EU regulation 2080/92 (IDF 2001).
Code
Country
Area (ha)
DE
Germany
26,249
DK
Denmark
2,725
ES
Spain
459,395
F
France
45,147
• Windfall in artificial spruce or pine forests may
induce a (natural or managed) change back to a
higher proportion of deciduous trees (see section
10.2.2).
• Free stand development (without clearing) in a
number of forest stands is an option to create new
ecological niches and therefore to increase bio-
diversity in forests, which is seldom realized in com-
mercial forests up to now. Because each stand is
changing its structure and its species composition
successively, a certain number of such stands of dif-
ferent ages should be present in a larger forest area
to maintain biological diversity.
• Using the natural regeneration potential may save
costs (for seeding, planting) and prevent root
deformations (causing bad tree growth); besides
this, it is a contribution to enlarging the genetic basis
of the tree populations involved. Nevertheless, pest
outbreak has to be prevented; fallen spruce is crit-
ical in this respect (it is a micro-habitat for, e.g.,
Ips typographus
,
Heterobasidion annosum
,
Armillaria
mellea
agg.), but an increasing share of broad-leaved
species will reduce this problem in the future.
IRE
Ireland
98,258
IT
Italy
64,162
PT
Portugal
205,768
UK
United Kingdom
100,868
BE
Belgium
191
ELL
Greece
16,401
LUX
Luxembourg
12
NE
The Netherlands
2,271
OST
Austria
343
SUO
Finland
19,732
SVE
Sweden
67
Total
1,041,589
regulation 2080/92 from 1992 (EC 1992b) aimed at
reducing the area of arable fields, to reduce subsidies
for surplus of agricultural products, to contribute
towards an improvement in forest resources as well
as of countryside management and environmental
balance, and to absorb CO
2
. In landscapes with high
agricultural intensity reforestation diminishes the
pollution of seepage water with nitrate, which often
is a problem in terms of purification of drinking
water (Kreutzer
et al.
1986, H. Fischer 1998). Reforested
natural retention areas can be an important contribu-
tion to flood regulation. Up to 1999 about 1 million
ha were reforested in Europe, mostly in Spain and
Portugal (Table 10.3), and still the calculated reforesta-
tion potential is enormous: in Denmark the political
reforestation aim is 500,000 ha (1995-2050), in Ire-
land it is 600,000 ha within 20 years, in Portugal it is
about 1.5 million ha within 50 years and in Germany
the scenario is 1.2 million ha or more (no time period
indicated; Weber 1998).
Reforestation of former agricultural land starts
with a soil that is settled by enormous numbers of
individuals of many species of micro-organisms and
insects; plant species may be present as a soil seed
bank or as established individuals, and the site is
Although from the point of view of economic forestry
storm events are real catastrophes, on the accepted
background of close-to-nature forestry they can be
understood as unexpected options to improve the
degree of naturalness in forests in the near-term.
10.5.4 Reforestation of former
agricultural land
In Europe
reforestation
(restoration of forests on
recently non-forested land that was forested in pre-
vious times) plays an important role in landscape
planning, since abandonment in the 1980s and 1990s
was common in many parts of Europe. The EEC
