Environmental Engineering Reference
In-Depth Information
logical restoration measures are now considered high-
priority tasks for the future.
12.3 STEPS TOWARDS FOREST
RESTORATION: BETWEEN PRIMEVAL
FOREST AND STERILE SUBSTRATE
The way from a recent situation of a certain part of the
landscape to a near-natural forest situation can be
short, if the recent vegetation stand is close to the site
potential (PNV). It may, however, be long, if the recent
situation is more or less far from the PNV stage. We will
start with the near-natural situation and fi nish with
considering bare areas waiting to be restored (use
Figure 12.1 as a guideline).
minor increase
increase
no change
Figure 12.5
Change in the representation of nitrogen-
indicating plant species in central European forests between
the 1950s and 1990s. (Modifi ed from A. Fischer 1999.)
12.3.1 Conservation: near-natural
forest management
Seen from a global point of view, forest utilization in
the temperate zone is a must if sustainability is set as
an overall goal in land use management. Growing con-
ditions for forests providing high-quality timber are
excellent here. The paradigm is that a long-term pre-
servation of forest ecosystems can be combined with
multifunctionality and utilization: timber production
and other socio - economic benefi ts such as biodiversity
protection, production of high-quality drinking water,
CO
2
storage, recreational purposes and the creation of
attractive landscapes. The goal is to change species
composition, forest structure and regeneration proc-
esses of remaining near-natural forests as less as pos-
sible while using the goods and services (Mansourian
et al
. 2005). For this purpose, a management approach
has been developed called 'Continuous Cover Forestry'
or, in recent terms, ' near - natural forestry ' or ' close - to -
nature forestry ' ( ' Naturgem ä sse ' or ' Naturnahe Wald-
wirtschaft') (Pommerening & Murphy 2004). It is
based on the following principles: (1) continuous and
uninterrupted maintenance of forest cover, (2) timber
harvesting by extraction of single trees or small groups
of trees, (3) mixed age classes, (4) promotion of native
tree species, including broadleaves, (5) mixed-species
composition instead of monocultures, (6) natural tree
regeneration instead of seeding or planting trees and
(7) conserving old trees and dead wood, habitat for
fungi, insects and vertebrates, as an important means
of maintaining species diversity.
the upper montane belt, and are starting to replace
beech there (Pe ñ uelas & Boada 2003 ). Non - native
species from adjacent areas may also invade and grad-
ually become new elements of the local communities,
as on the southern edges of the Alps, for example, ever-
green broad-leaved tree species such as
Trachycarpus
fortunei
,
Cinnamomum glanduliferum
and
Prunus lau-
rocerasus
, originally cultivated in gardens, are becom-
ing naturalized and leading to 'laurophyllization', to
use the evocative term of Klötzli and Walther (1999).
Nevertheless, although there is a close correlation with
climatic parameters, other causes such as changes in
land-use practices may also play an important role in
this change in species composition.
In China, protection of the remaining forests as well
as reforestation are seen as important tools to adapt to
new climate conditions (Natural Forest Protection
Program; Ting 2001). The causes of this type of
changes can be infl uenced neither by changing forest
management practice nor by restoration measures;
change is possible only by reducing emissions. Never-
theless, the consequences of increasing temperature
for forests are not interpreted as being entirely nega-
tive: for temperate forests generally, timber productiv-
ity is expected to increase by 5-6% over the next few
decades. In China, afforestation campaigns and eco-
