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This paper presents part of the evaluation of samples of soil fauna collected during a
6 month's stay in the Amazon rain forest region. At first is given a main division of this
region into different ranges by means of geological, climatological and ecological aspects,
followed by a more differenciated subdivision of the central amazonian rain forest near
Manaus by pedological, hydrological and plant ecological viewpoints.
Two Biomes can be distinguished, the Terra firme and the inundation area, the latter
characterised by the annual inundation by the big rivers. On the Terra firme two forest
habitats are clearly discernible, the timber forest (,,Hochwald") on loamy soil and the
Caatinga on podzol soil, which the ,,Palmetum" as transitive habitat in brook valleys can
be added to. In the inundation area also two forest habitats are discernible, the Várzea
forest on the embankment of white water rivers and the Igapó on tertiary sediments along
black water rivers, spatially linked by the ,,Igapó (Solimões)" in mixed water areas.
The examination of the makro-arthropod-fauna from surface samples and of the
meso-arthropod-fauna by Berlese samples (,,Berlese-Fauna") confirms the discrimination
of three habitats each in the two Biomes. The distinction within the two Biomes however
is dissimilar and owing to different facts: In Terra firme habitats density and composition of the groups of soil fauna are rather similar. On the other hand the discernible
spectra of species in timber forest respectively in Caatinga cause different biocoenoses'
whereas the ,,Palmetum" is inhabited by a not self-supporting fauna composed of parts
of the two other biocoenoses. In the inundation area however the spectrum of species in
the three habitats does not allow the discrimination of biocoenoses, but Várzea forest and
Igapó are clearly discernible in density and percental composition of the groups of soil
fauna.
By quantitative aspects the soil fauna of Terra firme forest in the central Amazon
region resembles those of other tropical rain forests in the world. In this regard these
tropical habitats and comparable forest habitats of Central Europe are similar too. The
soil fauna of central amazonian rain forest is characterised by high number of systematic
groups and species. In the single soil sample, about 40 species of oribatid mites, are found
the whole number of species in Terra firme forests being 110 - 130.
By quantitative and qualitative aspects the soil fauna of the inundation area is a so-called impoverished Terra firme fauna. The number of oribatid species per sample
varies between 12 and 24, the whole number of species being 75 - 90. Almost all of
these species are also found on Terra firme. In the inundation area the number of
endemic species is extremely low.
The number of oribatid species on Terra firme is highest in the central Amazon region
since most of endemic species are to be found here and because these species lacking in
marginal regions are not superseded by species living outside of the amazonian rain forest.
The biological bearing of the soil fauna from rain forests is shown by the facts:
secondary decomposers take place of primary decomposers, big digging forms are lacking,
and earthworms, when in number, belong to an special type of nutrition which have no
importance in producing clay-humus-compounds.
