The biosciences focus their narrative on the diversity of life. It starts with the biological diversity ‘on our doorstep’: the abandoned Hauenstein quarry, on the edge of the Mariatrost district of Graz, has developed into one of the richest small regions in Styria. The space encourages you to study biological gems in the wild based on the knowledge you have gathered.
Biodiversity encompasses the entire variety of genetic variants, species, habitats and ecosystems. It exists naturally not only in tropical rainforests, but also right on our doorstep. One example of extremely high diversity is the Hauenstein, a small hill on the north-eastern outskirts of Graz. In the now defunct quarry area, different habitats can be found in a very small space which form the basis for a rich flora and fauna.
The Hauenstein from its ‘best side’
Rock face, mixed deciduous forest above, ruderal area below and neighbouring dry meadow. The diversity and interconnectedness of habitats in a very small area and the favourable climate are the basis for a rich plant and animal life.
Image Credits
The rock face - an extreme habitat!
Rock faces are the most impressive remnants of the former mining site. Once as now, they are extreme habitats and are only colonised by a few specialists from the plant and animal world. The lack of space is particularly limiting. In addition, the environmental conditions vary greatly: There is hardly any water-retaining soil and the strong solar radiation leads to large daily temperature fluctuations.
Small plants predominate, which penetrate deep into niches, cracks and crevices with their roots. Hair or dry leaf remnants protect against evaporation, while fleshy leaves serve to store water. Small animals concentrate on the overgrown rocky areas, but can also colonise smooth and overhanging walls. Wall lizards heat up on the warm rocks to reach operating temperature and thus maximise their activity, and ant lions set up their funnel traps in sandy places protected from the rain.
But larger animals are also on the move on the rock face: a chamois regularly appears, often remaining motionless as it observes its surroundings. It may have come from Plabutsch or the Schöckl region, where forest chamois live on the ground. In contrast to goats and young animals, chamois live as solitary animals and roam widely.
The bottom of the former quarry: hotspot of biodiversity or unattractive ‘Gstättn’?
An extensive, flat ruderal area is in front of the rock face. It was created by the accumulation of stones and rubble, was initially covered with little fine soil and humus and was therefore only sparsely vegetated. Numerous pioneers from the plant and animal world are closely adapted to these conditions. The Sal willow, for example, was one of the first colonisers due to its hunger for sunlight. The same applies to the blue-winged grasshopper, which loves warmth and dryness. It is only well camouflaged as long as the proportion of unvegetated sandy areas is high. Over time, nutrients gradually accumulate due to dead plant remains and the input of atmospheric nitrogen.
The vegetation becomes denser, and gradually rare plant and animal species tied to open soils are replaced by ‘common species’. The first woody plants appear. The impression of an unkempt and overgrown ‘Gstättn’, as such ruderal areas are popularly known, increases.
Meadows all around
There are several colourful flower meadows in the vicinity of the quarry area. The poorer in nutrients and drier, the more colourful - this rule of thumb also applies here. A lack of fertilisation and mowing once or twice a year are the prerequisites for a particularly rich variety of species. If intensification takes place, many plant and animal species can no longer exist, cannot find suitable food or are displaced by more competitive species. If extensification, i.e. mowing or grazing, is abandoned for several years, scrub encroachment quickly sets in and emerging woodland ends the flourishing meadow life.
Forests shape the general view
In addition to rocks, ruderal areas and meadows, the Hauenstein is mainly characterised by forests. Most of them are extensive mixed beech forests, which only allow a few shade-tolerant shrubs and herbs in the lower tier due to their dense canopy. It is only before the beech trees bud at the beginning of May, when the sun's rays still reach the ground, that a host of spring bloomers such as larch spurge, wild garlic and wood anemones appear.
Many typical forest-dwelling animal species are strictly bound to structures. For example, the black woodpecker needs old trees to create its breeding holes, the fire salamander needs small springs in which to lay its larvae, and numerous small animals need a thick, moist layer of leaves. Species diversity is particularly high at the edge of the forest, where different habitats meet, but decreases significantly in the interior of the forest.
Everything is connected!
On the Hauenstein, there are many influences, interactions and dependencies between habitats and species. Sparsely vegetated areas of ruderal land can only exist in the long term, for example, if either humans intervene with measures or natural dynamics contribute to the continuous creation of nutrient-poor areas through the demolition of rock sections. One inhabitant of these areas, the long-legged pillwort, is a particularly thermophilic species. Another prerequisite for its occurrence is the presence of sheep dung, which it prefers for feeding and developing its larvae.
If there are also well-connected habitat conditions, such as the immediate proximity of grazed and uncultivated areas, this creates particularly favourable conditions - as is the case on the Hauenstein. The relationship between animals and plants is also highly complex. For example, many insects, such as bees and butterflies, depend on very specific plants as a source of food, a place to sleep or a nursery.
Species richness: despite or because of human influence?
We know from old stories that the southern side of the Hauenstein was once characterised by dry meadows covered in shrubs. This near-natural and certainly species-rich ensemble was almost completely destroyed by the development of the limestone quarry. After quarrying ceased, however, nature quickly began to reclaim the area and ‘second-hand habitats’ developed. Plants and animals from neighbouring areas invaded the area left to its own devices and brought about a renaissance in biodiversity.
Warmth-loving and drought-tolerant species, most of which are rare and endangered in our landscape today, were able to spread here again and establish themselves in the long term.
Progressing development
As positively as the biodiversity of the area has developed since the limestone quarry was closed down, it is now being rapidly degraded. Open land species are becoming rarer, unutilised areas are gradually beginning to become overgrown with bushes and in future there is a risk that they will be replaced by a comparatively species-poor forest ecosystem. With human help, however, intermediate stages, such as a meadow or a ruderal area, can be maintained in a species-rich state through ‘biotope management’. The planning principles required for this result from our own research findings. Measures include mowing, grazing or the targeted removal of emerging woody plants.
