出版社：Arbeitsgemeinschaft Forstliche Standorts- und Vegetationskunde (AFSV)
摘要：Naturalness is one of the most important criteria in nature conservation. This
paper examines the fundamental concepts underlying the definition and assessment
of naturalness. Its role in nature conservation and forest management under
conditions of global change is also discussed. The degree of naturalness may be
defined in ordinal classes. The “static” concept of the potential natural
vegetation (pnV), developed in the 1950ies, is mostly used as the reference
state. In other cases, its reversed concept, the hemeroby (degree of
articifiality) is assessed, based on the intensity and frequency of human
impacts. Since the 1970ies, more attention has been given to natural dynamics
than in earlier approaches, e.g. in forest succession models. At the end of the
1980ies, the previous importance was increasingly stressed of natural browsing
by large herbivores and the role of predators. These large herbivors are extinct
today in most cultural European landscapes. It is assumed, that they open up the
canopy, and create park-like forest structures which contain a diversity of
habitats for other types of organism (birds, insects). Changed and permanently
changing environments and altering patterns of competition between species
continue to modify natural processes today. Some of the more conspicuous effects
are the extinction of native species and immigration of species to new regions.
Long-lived ecosystems like forests are however not able to adapt quickly to such
changes and may be unable to find a new balance with the environment. Today,
such changes occur very rapidly, and are reducing the original naturalness of
ecosystems. Because of this, the criterion “naturalness” must be downweighted.
Conversely, more importance should be attached to other criteria: particularly
originality (= original naturalness) and restorability. Forestry is contributing
to this accelerated change of biocoenoses by increasing disturbances and
introducing exotic tree species. Naturalisation of some exotic tree species
modifies the natural processes and creates a “new allochthonous naturalness”.
Because of this, forest planning should try to preserve or restore stands with
attributes of the “original forest”. Exotic species should not be planted, or
only in a very restricted way. Key words: naturalness, hemeroby, originality,
human impacts, global change, forestry, nature conservation.
