GeoPark Kaolinrevier Hirschau
<<
InfoPoint No. 3

 

-

_

 

Restoring small streams to their natural state
‘Renaturation’ means the restoring of habitats to their original state. ‘Recultivation’, in contrast, is the regeneration of a region destroyed by human intervention, and the subsequent recreation of a new cultural landscape.

The Naab Hills, a high ridge that borders on the south of the kaolin-mining district, are drained by small streams flowing north-eastwards into a larger stream called the Ehenbach. This stream, being a receiving stream, flows to the north of the mines and the natural connection is thus blocked by the pits. This means that the natural functions of the flowing water are seriously impaired. Efforts are therefore being made to reduce these negative effects by restoring the streams to their natural state.

_

_

A map dating from 1769 showing the old highway to Nuremberg with the villages of Hirschau and Schnaittenbach.
The enlarged section shows what the area was like before mining began.

 

The Weitzendorfer Bach and his flowing into the Ehenbach

_

_

blue and green: the original course
red: the present-day diversion

 

The secondary biotope
Enormous quantities of quartz, feldspar and kaolin have been extracted since people began mining the raw materials here in 1833. Such large quantities of rock can no longer be replaced. The original cultural landscape has disappeared and a secondary biotope has established itself. Basically, secondary biotopes can develop wherever man alters landscapes as a result of his activities and then leaves them to redevelop freely. This is particularly true of the mining of the raw materials in the Hirschau-Schnaittenbach Valley. Even now, while the raw materials are still being extracted, stretches of land in the extensive pits remain almost undisturbed, or even completely untouched, for a long time, sometimes for years on end. Water collects temporarily, or occasionally permanently, in puddles or tiny pools that come into being by chance; alternatively it collects behind intentionally placed barriers. Between these patches of water lie patches of sandy soil with no vegetation or with just a few plants growing in them.

Such environments are called pioneer sites. They are colonised by so-called pioneer species, which are able within a very brief space of time to take over habitats like these which have very little vegetation. This happens despite the fact that such a habitat is characterised by extreme conditions. The surface can heat up dramatically in summer, the soils contain very little nutrition, and almost nowhere is it possible to shelter or to hide.

Pioneer sites can therefore be colonised by only the very small number of real specialists who have adapted most successfully to the extreme conditions. On the other hand, such species require difficult conditions like these because they are unable to compete with other species in areas of dense vegetation.

 

The natterjack toad
A really typical example of a pioneer species in these open-cast mines is the natterjack toad, an amphibian which is classified as being seriously at risk on Bavaria’s Red List of endangered species. It lays its spawn even in patches of water that have only just appeared and have, as yet, no vegetation at all. Even inconspicuous puddles at the side of a road or a track are used for breeding purposes. In other ways, too, this toad’s way of life is ideally adapted to the pioneer character of its habitat. Many amphibians remain attached all their life to the body of water in which they were born. In contrast, the natterjack toad is mobile and does not always return to the same place to spawn. As a result, it can find and colonise newly created patches of water within a very short time.

What is more, the natterjack toad is primarily nocturnal, and buries itself in the loose substrate in the kaolin pits during the day. Thus it is not exposed to the summer heat. If the toad were active during the daytime, it would also be completely at the mercy of enemies because its habitat would offer little shelter due to the lack of vegetation.

This toad has adapted to its surroundings in another way: its cycle of development from the egg to the young animal that can survive away from water is relatively short. Since the mostly small, shallow puddles used for spawning occasionally dry up before the end of this cycle, more eggs are laid as soon as it rains again. In view of the extensive area of land offering an ideal habitat for this species, the natterjack toad can be said to be a characteristic species in the kaolin mines in the Hirschau-Schnaittenbach Valley.

 

_

_

Tadpole of a natterjack toad

_

_

the natterjack toad