Inland dune
Inland dunes and drifting sand fields in Central Europe are spatially separated from the coastal dunes on the North and Baltic Sea coasts . They are aeolian formations made of sand ( dunes ) brought about by the wind . They were mostly blown under cold climatic, periglacial conditions at the end of the Vistula and Würm Ice Age , i.e. a little more than 10,000 years ago. Their development in the post-ice age is mainly based on the influence of humans.
Formation of the inland dunes
In Central Europe, at the end of the Vistula and Würm Ice Age, it was around 10 degrees colder than it is today. Therefore there was no tree growth and only a patchy cover of vegetation in the form of the tundra . In addition, in the areas reached by the glaciers , when the ice melted back, the vegetation first had to re-establish itself. Thus the power of the winch could work almost unchecked. Light, fine-grained soil particles, especially silt and sand , were caught in the air currents, often transported for miles and deposited elsewhere. The sorting effect of the wind - silt is transported much faster than sand - over time, areas of drifting sand and dunes were created in many places, while the silt was transported further and, for example on the northern edge of the low mountain range, was deposited again as loess .
The dunes were able to "wander" in strong winds. Most of the inland dunes that exist today were created at this time. With the end of the Ice Age , the activity of the dunes quickly came to a standstill as a result of reforestation.
The shape of the inland dunes varies depending on the prevailing wind directions and strengths. Usually it is rather irregular dunes or drift sand covers. But there are also very well developed parabolic and longitudinal dunes.
Almost all of the more recent phases in which the inland dunes developed further are linked to human interference with the vegetation cover. Fixed inland dunes were reactivated by deliberate or unintentional clearing of the forest. On the basis of the charcoal particles trapped in the dunes and their dating using the radiocarbon method , it was possible to establish that the dunes were reactivated again with the settlers of the Neolithic Age . But there was also man-made dune activity in the Bronze and Iron Ages .
Inland dunes in the Middle Ages and in modern times
After the Migration Period, one of the main phases of forest destruction and thus the activation of dunes began in the Middle Ages . The sand drifts became a serious problem for many settlements. In order to protect their pastures and settlements from the sand drifts, people began during the Middle Ages to cover the dunes with frugal and deep-rooted trees, e.g. B. with pines to be planted. Due to heavy grazing, the activity of the inland dunes continued into modern times . Systematic afforestation of the dune areas did not begin until the 18th century, so that only a few inland dunes are currently active in Germany. The forest pine ( Pinus sylvestris ) is nowadays the characteristic forest tree (main species) for drifting sand areas and inland dunes.
Significance and endangerment of the inland dunes
Large-scale sand excavations for structural measures (settlement and road construction) as well as the sudden expansion of asparagus cultivation since the 19th century and the general urban sprawl and development of the landscape have led to a noticeable decline in this already rare type of biotope in the last few centuries . The risk varies from region to region in Germany. While there are still numerous dry biotopes on dunes in the sparsely populated and sandy Brandenburg , they are extremely threatened in North Rhine-Westphalia . The drifting sand areas outside the core areas of the inland dunes are absolutely worth protecting and conserving from a species protection perspective.
The high temperatures and evaporation rates during the summer months as well as the general lack of nutrients result in a rich inventory of warm and dry-loving plant and animal species (sandy grass vegetation, grasshoppers , wild bees ).
The sandy soil is not able to store large amounts of water. Character plants of the dunes are the sand thyme ( Thymus serpyllum ), the silver grass ( Corynephorus canescens ), the blue-gray crest ( Koeleria glauca ), the hornwort ( Cerastium semi-decandrum ) and the sand strawflower ( Helichrysum arenarium ). As successfully as the dune plants thrive in warm, dry locations, they have little chance on normally moist soils, where they are always subject to competition from fast-growing species. Most of the plants mentioned have a very close ecological bond with dunes and areas of drifting sand. Most species of the grassy sand society are endangered and are legally protected by the BArtSchV .
Sand turf can set in relatively quickly on larger open or ungrown sand areas. Mostly grasses and herbs are the first to colonize, followed by mosses and lichens adapted to dry locations over time . After several years, these reach their optimal expansion. If there are no soil disturbances, the sand lawns will quickly be overgrown by semi-arid lawns or woody trees in a natural succession in a situation of climate change . The plant communities of the sandy lawn can only survive in places where open sand areas are created again by footsteps and grazing.
Larger dune areas usually require little maintenance. In the medium term, the main focus is on avoiding heavy growth of wood and trees. Measures of official and voluntary nature conservation have proven to be effective: "plagging" matted and bushy sand lawns, removing the uppermost, mostly humus, soil layer so that open sand areas are formed again. However, this maintenance measure should always be carried out under the supervision of competent persons. On dune areas where larger rabbit populations exist, the wild rabbits ( Oryctolagus cuniculus ) help to keep small areas free in a natural way through their constant scratching and digging.
In the area of sensitive drifting sand fields, walkers should generally stay on paths and paths and not leave any litter in the open landscape (nutrient input). In this context, dog feces are a danger to grassy sand societies.
Inland dune areas in Germany
The largest inland dune areas in terms of area are in northern Germany , due to the sandy deposits of the Pleistocene glaciers. The distribution varies from region to region and can change on a small scale. Sander and dry glacial valleys are considered to be particularly rich in dunes . It is irrelevant whether they are in the old or young moraine area. Well-known dune-rich landscapes include the Lüneburg Heath and southern Brandenburg , for example with the inland dune Waltersberge .
One of the last active shifting dunes in inland Germany is in the Nuthe-Nieplitz Nature Park in Brandenburg . On a former Soviet military training area, the closed nature reserve Forst Zinna Jüterbog -Keilberg , the dune was reactivated by forest fires due to the military use of the GSSD and is still active. Their (albeit illegal) use as a cross route for bicycles and sometimes motorcycles effectively prevents them from growing again. The largest active shifting dune is the one on the Fuchsberg near Gommern in Saxony-Anhalt , which has already lost a lot of its size due to excavations.
In the Upper Rhine Plain , an approximately 130-kilometer-long band of dune areas extends from Rastatt to Mainz. Various inland dunes are protected here, such as the Schwanheimer Düne , Sandhausener Dünen or the Mainzer Sand . There are dunes up to around 20 meters high in the Iffezheimer Sand Dunes , the Hockenheimer Hardt and the Schwetzinger Sand . The mightiest inland dunes are located in the area of the Oftersheim dunes and the Speyer training area .
The Franconian sand axis extends from Bamberg to Weißenburg in Bavaria . The maximum extension is 100 km in north-south direction and 40 km in east-west direction.
The inland dunes nature reserve near Siegenburg and Offenstetten is located in the Lower Bavarian district of Kelheim .
On the Münsterdorfer Geestinsel the " Binnendünen Nordoe " have been designated as a nature reserve since March 2013 .
The Wedding dune is the last inner-city ice age dune in Berlin . In Bremen there is the Mahndorfer dune and the Bockhorn inland dune in Bremen-Nord .
Inland dune areas in Austria
The dune and drifting sand areas of the Marchfeld in Lower Austria were created during the last ice age and in the subsequent post-ice age . Fine sediment removed by the wind from the extensive sand and gravel banks of the rivers, especially the Danube , was deposited in the area of today's villages of Oberweiden , Weikendorf , Obersiebenbrunn , Lassee and Marchegg (Richtberg) and led to the formation of inland dunes. The preserved sandy areas of the Marchfeld are part of the European protected area "Pannonian Sand Dunes" and some, such as the Oberweiden sand mountains , are also designated as nature reserves. Due to their special vegetation, they are among the most valuable habitats in Austria. Some types, such as B. the late carnation , a rare Pannonian floral element , have their only occurrence there in Austria.
Fauna of the inland dunes of Central Europe
Numerous animals have specialized in the special habitat of sand dunes . They are commonly referred to as psammophilic . The extreme living conditions require special physiological and ethological adaptations. Among the abiotic factors , the extreme fluctuations and maxima of the temperature are to be mentioned in particular, but also the predominantly high dryness of the top soil layer.
The surface of open sandy soils shows extreme daily and seasonal temperature fluctuations. Since the pores of the sand are large, they store little water and conduct heat poorly. On the inland dunes of the Upper Rhine Valley, temperatures of up to 70 ° C can be measured during the day, and only 17 ° C at night. Only specialists can survive such temperatures. However, the temperature drops already one centimeter below the surface and fluctuations during the day are minimal at a depth of around 10 cm. Numerous ground-living or burrowing species take advantage of this fact.
However , there is no lack of generalists in sand dune areas.
Mammals
Among the mammals , the wild rabbits (Oryctolagus cuniculus) are particularly favored by the loose soil . Their density is highest in the areas overgrown with bushes ( blackberries ). Through their construction activities, they help to ensure that at least smaller areas are regularly open again for primary settlement. However, their number is limited by the sparse vegetation , especially in midsummer . Since sandy areas are usually very heterogeneous , there are regularly numerous other mammals that are not specific to inland dunes.
Wild rabbit
rabbit hole
Birds
Among the birds are the rare, at least previously regular residents and guests of the sand dune areas: goat milkers , hoopoes , woodcock , common pipit , woodlark , skylark , lapwing , red-backed shrike and tree falcon . Mostly these are types of open arid landscapes and loosely wooded sandy soils, i.e. areas that are only present in small areas in Central Europe. These birds are particularly threatened by the great pressure to spend their leisure time and so today there are predominantly cultural followers . It is not only the woodlark that suffers from the numerous dogs that run freely .
Goat milker
Skylark
Red-backed Shrike
Amphibians and reptiles
Among the amphibians , the sand habitat with its heterogeneous structure and the alternation of open sand areas with open small bodies of water is ideal for the natterjack toads. The animals can also be found on the driest and steepest sandy surfaces, in the sand during the day or hidden under stones and woods. The common garlic toad also prefers soft, sandy soils into which it burrows during the day. Due to climate change and decreasing rainfall, small temporary water points are increasingly rare in these dry habitats. In Eastern Europe , the green toad is found in the same habitat. Otherwise, depending on the type of water, other amphibians (common toad, common frog, pond newt) are also present. Among the reptiles , the sand lizard prefers the edge areas of the open sandy areas. Here she also finds ideal conditions for the egg clutches. In the presence of water can also grass snakes occur.
Natterjack toad
Common Garlic Toad
Pond newt
Sand lizard
grass snake
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Butterflies
The sandy area near Speyer is home to more than 670 butterfly species (Bettag, 1989). There are no species of butterflies that occur exclusively in this habitat. Nevertheless, the small fire butterfly can be considered typical . A regular inhabitant of the sand dune areas is the little peacock butterfly , whose caterpillars also live on blackberries and common heather . Since lichens are common in this habitat, there are also numerous lichen bears (e.g. the gray-bodied lichen bear ) whose caterpillars only feed on them. Many borer can also be considered typical dune dwellers (e.g. Dioryctria simplicella ). The high biodiversity is directly related to the high diversity of the plants on which the caterpillars live. For example, the wood drill Parahypopta caestrum is dependent on wild asparagus . For the rams Zygaena laeta and Zygaena punctum , the man litter provides the basis of life. Spurge Spinner and Spurge Hawk feed on milkweed -Gewächsen.
Little fire butterfly
Small peacock butterfly
Milkweed spinner
Milkweed hawks
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Beetle
Typical sand dwellers are among the ground beetles : Amara fulva , Amara spreta , the moon spot beetle Callistus lunatus , Licinus depressus , Bembidion tetracolum and three tiger beetles , field tiger beetles , forest tiger beetles and dune tiger beetles . The latter can be observed when hunting in areas with a temperature of 70 ° C. Since the larvae of numerous species of scarab beetles live in the soil, there are distinct types of sand among them. The largest include the Walker and Anoxia villosa , which are similar to the cockchafer , while the smaller ones include the hair-scale tree beetle Maladera holosericea . The species interested in excrement include the bull beetle and the species Psammodes sulcicollis and Rhyssemus germanus, which are typical of dunes . The bull beetle creates tubes up to 1.5 m deep into which it mainly carries rabbit droppings.
Dune tiger beetle
Walker
Anoxia villosa
Hymenoptera
Among the hymenoptera there are numerous species that have adapted to sand dunes and are therefore dependent on them. For example, some pottery wasps of the genus Eumenes need sand as a building material for their nests. This habitat offers ideal conditions in particular , as digging wasps in the sand can be carried out without high expenditure of energy. In addition, in contrast to the wild bees, they mainly use their front legs to dig. In addition to the widespread beewolf , the large gyroscopic wasp is a characteristic species of the semi-open sandy areas overgrown with silver grass, where it forms colonies . The animals hunt flies , especially hoverflies and horseflies , which they use to provide food for their larvae throughout their development. After each feeding, the nest entrance is carefully closed with sand. A species that is spreading in Central Europe is the locust sand wasp, which also creates its nests in the sandy soil. The adult animals like to visit the flowers of the field man's litter . Even at the hottest lunchtime, wasps fly over the dune ridges in search of spiders . Numerous species can only be found in this habitat.
Around one in four of the more than 450 Central European wild bees is a resident of the sandy areas. Many build their nests in the loose sand, others specialize in the plants that are typically found here, such as the steppe bee Nomioides minutissimus , which visits the sand thyme . The asparagus bee ( Andrena chrysopus ) is also dependent on wild asparagus . Nests in the sandy soil are created by several sand bees of the genus Andrena or silk bees of the genus Cerceris . So you can see Colletes cunicularius and its parasite Sphecodes albilabris very early in spring . The trouser bee Dasypoda hirtipes creates particularly deep nests with over half a meter. There is always a high pile of sand at the entrance.
Gyro wasp
Locust sand wasp
Silk bee
Trouser bee
Blood bee
Two-winged
Among the two-winged species, some species from the stiletto and predatory flies families are particularly adapted to raw sandy soils. Numerous species of the genus Thereva are represented on the dunes, the larvae of which hunt for the larvae of other insects in the upper layers of sand. The larvae of the predator flies mostly inhabit deeper layers. Their adult animals are masterful hunters. The small sandwich ( Stichopogon elegantulus ) lurks at the edge of open sand areas, from where it hunts other insects in flight. The much larger sand predator fly ( Philonicus albiceps ) also sits on the bare and often very hot sand. The females of both species have a ring of thorns at the tip of their egg-laying apparatus, with which they drill a cavity in the sand to lay eggs. The behavior of the large wolf fly ( Dasypogon diadema ), which sticks the eggs with sand before actually laying them, is even more complex . Numerous parasites of wild bees can be found among the closest related woolly levers .
Lynx fly
Small sandwich
Sand predator fly
Big wolf fly
Great wool floater
Grasshoppers
Among the grasshoppers , some species are dependent on the special plant community, open soils for oviposition and locomotion and the often high temperatures. Fast conquerors include the blue-winged wasteland insect , the blue-winged sand insect , the steppe grasshopper and the Italian beautiful insect . Another pioneer species is the spotted club horror . The animals are often found in large numbers of individuals, but because of their good camouflage they can only be discovered by scare away. The locust sand wasp's victims include the two-colored bite insect .
Blue-winged wasteland cricket
Italian beautiful insect
Spotted club terrier
Two-colored bite insect
Dragonflies
On the one hand, the open area simply serves the dragonflies as a hunting area, on the other hand, the larvae of numerous species develop in the waters in and on the edge of the sand dune areas. However, no species specializes in sandy areas. The widespread great darter and the great pitch dragonfly are common .
Great darter
Big pitch dragonfly
Bed bugs
As with butterflies, the predominantly plant-sucking bugs include a large number of specialized species. The broad dune bug ( Phimodera humeralis ), Menaccarus arenicola and Pionosomus opacellus are considered to be strictly psammophilic .
Reticulated winged
In Central Europe, the common ant virgin ( Myrmeleon formicarius ) and the spotted- winged ant virgin ( Euroleon nostras ) are relatively common on sandy surfaces. Your larvae are dependent on this habitat. The nocturnal search tracks of the larvae can be regularly discovered next to the pits.
pit
larva
Imago
be crazy
Typical spiders adapted to sand dunes are jumping spiders , which usually do not build nets and jump at their prey. To the occurring in sand dunes types include the jumping spider Yllenus arenarius , Phlegra fasciata , Aelurillus v-insignitus , the cross Spring spider ( Pellenes tripunctatus ) and the zebra spider ( Salticus scenicus ). The males of the red tube spider ( Eresus kollari ) can be seen looking for the females on open dunes, especially in late autumn. The latter are found less often because they do not leave the earth tubes.
The wolf spiders Arctosa perita and Alopecosa fabrilis hide in sandy earth tubes , the fat spiders Steatoda albomaculata and Asagena phalerata weave their webs between low vegetation and the sandy soil , and the running spider Tibellus maritimus can be found on rough grass .
Because of the higher temperatures and the drought, the field angle spider ( Tegenaria agrestis ), the basket spider ( Agalenatea redii ), the labyrinth spider ( Agelena labyrinthica ), Gibbaranea gibbosa and Phylloneta impressa also live here . The wet nurse's thorn finger ( Cheiracanthium punctorium ) also lives on the edge of open dunes .
Aelurillus v-insignitus
Pellenes nigrociliatus
Thorn finger
Tube spider
Alopecosa fabrilis
Individual evidence
- ↑ State ordinance on the nature reserve "Binnendünen Nordoe"
- ↑ Ice Age in Wedding - Germany's last inner-city Ice Age dune visible again. berlin.de, February 16, 2012, accessed January 25, 2013 .
- ↑ http://www.ag-binnenduene.de/
literature
- ALISCH, M. (1995): The Aeolian Relief of the Middle Upper Allern Lowlands (Eastern Lower Saxony) - late and post-glacial morphogenesis, expansion and definition of historical sands, sand excavations and protection aspects. - 176 p .; Cologne. - [Cologne Geographical Works, H. 62]
- ALISCH, M. (1994a): Critical weighing of natural process components in the causal complex of the Holocene drifting sand reactivation of the Central European inland. - In: 1. Central European Geomorphologentagung Wien 1994, 19. – 21. July 1994 [proceedings]: pp. 91-92; Vienna.
- ALISCH, M., & BRUNOTTE, E. (1992): Current aeolian morphodynamics of the inland dunes and drifting sand plains in the Allerniederung near Gifhorn. - In: GRUNERT, J., & HÖLLERMANN, P. [Ed.]: Geomorphology and Landscape Ecology. A compilation of contributions on the occasion of the 17th day. of the German working group for geomorphology in Bonn 1991: pp. 186-195; Bonn. - [Bonn geogr. Dep., 85]
- BETTAG, E. (1989): Fauna of the sand dunes between Speyer and Dudenhofen. - Pollichia book 17: 148 p .; Bad Dürkheim.
- PHILIPPI, G. (1973): Sand corridors and fallow land with low-lime drifting sands in the central Upper Rhine area. Publ. Landesst. Nature conservation and landscape management Bad.-Württ. 41: 24-62.
- PYRITZ, E. (1972): Inland dunes and drifting sand plains in the Lower Saxony lowlands. - Göttinger Geogr. Abh., 61: 153 p .; Goettingen.
- PYRITZ, E. (1974): Aeolian processes on an inland dune in the Allertal. - Dep. Akad. Wiss. Göttingen, math.-phys. Kl., 3rd episode, 29: pp. 219-225; Goettingen.
- VOLK, 0. H. (1931): Contributions to the ecology of the sandy vegetation of the Upper Rhine Plain. Magazine f. Botany 24: 81-185, Jena.
