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Conservation of species, processes and resources against the background of faunistic investigations of the forest canopy

Ammer, Ulrich, Schubert, Holger
Forstwissenschaftliches Centralblatt 1999 v.118 no.1-6 pp. 70-87
Araneae, Coleoptera, Fagus, Heteroptera, Larix, Picea, Quercus, arthropods, deciduous forests, forest canopy, forest habitats, mixed stands, species diversity, trapping, trees, Germany
We captured arthropods in three commercial forests with different degrees of naturalness and two unlogged forests (out of management for the past 20 and 90 years) in the Hienheimer Forst near Kelheim (Germany). We chose 39 trees (oak, beech, spruce and larch) using different trapping systems. Four of the captured taxa were determined to species (Colepotera, Araneae, Neuropteroidea and Heteroptera). The results indicate a strong dependence of beetle species diversity on the naturalness of the sites. This is mainly due to the great proportion of saproxylic beetles within the total amount of species.The number of spider species are comparable in natural and commercial forests. They mainly seem to depend on strucutral elements which are not necessarily correlated with the naturalness of a site.Also, the neuropteroids and true bugs do not exhibit any clear relationship to the naturalness of the sites. The species diversity in commercial broadleaf forests is comparable to that of the unlogged sites. The majority of the species are typical inhabitants of light and warm habitats and therefore bound to light-demanding tree species such as oak and larch.The results of the canopy traps show that the amount of species in commercial forests does not have to be less than that in nature forests, especially in mixed stands where oak is involved. Pure spruce stands, on the other hand, exhibit lower values for species diversity. But this is also true for unmixed beech forests, the natural vegetation unit for a large proportion of our landscapes.Consequently, the conservation of processes, i.e. focusing on the maximation of naturalness of our forests, interfers with the other possible goal of maximizing species diversity.For the maintainance and promotion of species diversity one should focus on using forest habitats in a way that ensures high diversity of tree species and structures. To take into account the demands of the protection of natural ressources one has to extend the visual angle as discussed in this article.The controversal results raise a lot of questions that demand further investigation. Predominantly this is the further exploration of our domestic commercial forests. Only a deeper insight into used systems can reveal which structures relevant to conservational issues those areas already carry and which are lacking. Observing conservational aspects in commercial forests is an important chance to secure important habitats on a large environmental scale that should not be missed.