The yellow-bellied toad, natterjack toad and common midwife toad are pioneer species
Amphibienarten, die einen dynamischen Lebensraum benötigen mit immer wieder neu entstandenen Tümpeln, offenen Flächen und lockeren, sandig-steinigen Schüttungen oder Böden, nennt man Pionierarten und beschreibt ihren Lebensraum als Pionierhabitat. Dazu gehören die Amphibienarten Gelbbauchunke und Kreuzkröte. Wegen ihres speziellen Anspruchs an den Lebensraum besiedeln sie gerne Flächen der heimischen Rohstoffgewinnung wie Kiesgruben, Sandabbaugebiete und Steinbrüche. Die Geburtshelferkröte hat ähnliche Ansprüche und kommt deshalb oft zusammen mit der Kreuzkröte und Gelbbauchunke vor.
Industry in the Aachen CitiesRegion benefits target species
In the Aachen CitiesRegion, too, a large part of the populations of the yellow-bellied toad, natterjack toad and common midwife toad live in habitats that are the result of commercial or industrial activities. These are the pit heaps from coal extraction such as in the nature protection areas of Noppenberg and the Carl Alexander mine dump, a number of active and former limestone quarries in Stolberg, and also mine dumps from ore extraction and metal processing as well as loose rock excavations such as gravel pits and sandpits. Habitats for the target species also resulted from military training operations such as in the FFH protected areas of Münsterbusch, Münsterbachtal and Schlangenberg.
Disturbance is vital
Due to the large number and close interconnection of these secondary habitats in the Aachen CitiesRegion, the target species have been able to survive in the project region until today. Nevertheless, because of structural changes in regional industry and the reduction of military training operations in the past decades, there has been a substantial loss of suitable habitats for pioneer species and thus a continuing decline in population sizes here as well.
This is because pioneer species depend on the continuous creation of new bodies of water that are not colonised by predators, and on the maintenance of the open character of their habitats by people, either through use or maintenance measures, particularly since their natural habitats – dynamic river and stream floodplains – have almost disappeared.
If people fail to take action, that would lead to bodies of water disappearing or being taken over by competitors or predators, and that shrubs, bushes and eventually even trees would take over the terrestrial habitat of the amphibians. The temporary bodies of water especially – puddles and ruts – that are important for the natterjack toads and yellow-bellied toads would disappear without use because of the lack of compaction needed.
Thanks to intensive nature conservation efforts (government nature conservation, nature conservation associations, the Biological Station), the decline of the target species in the project region was able to be stopped on the whole, however, numerous occurrences in the meantime have become extinct and most of the occurrences still known are in a conservation status that is bad or inadequate.
Which habitats do pioneer species use?
For the protection of the species, it is important that all sub-habitats, the bodies of water and the terrestrial habitat are suitable for the animals. Suitable places on land for hiding and overwintering are important, as is sufficient opportunity for capturing prey.