Dwarf heather
As a dwarf shrub one is vegetation type referred to in the dwarf shrubs from the family of heather plants predominate. If juniper stands also grow in the area, it is sometimes referred to as juniper heather . Juniper heaths, however, also refer to juniper-rich limestone grasslands in southern Germany (juniper is soil-vague and occurs as a pasture weed on both acidic and basic soils).
The tundras of the polar climates are also often dwarf shrub heaths.
Vegetation breakdown
Together with the grass turf , the dwarf shrub heaths form the class Nardo-Callunetea in the plant-sociological system. Heath and grass grass both grow on acidic to strongly acidic soils and are usually the result of extensive grazing; therefore they are similar in species composition and often occur next to one another or interlocked with one another. The "real" dwarf shrub heaths form the order Vaccinio-Genistalia (also Genisto-Callunetalia according to other authors). Heaths are species-poor societies, most of the plant species growing in them are also found in other vegetation stands of strongly acidic soils. It is therefore difficult to break them down according to the plant-sociological system, which is based on types of character . But because they are easily recognizable and highly characteristic from the landscape impression, their independence has never been contested.
Calluna Pagans
On dry sandy soils usually is heather ( Calluna vulgaris ) which consisted formative and characteristic way. As the nature itself is spreading the type of vegetation, especially near the sea (in the Atlantic climate). Calluna heaths occur in western and north-western Europe in a wide belt from the mountains near the sea in Portugal via western France, Ireland, England to Denmark and Norway, but mostly not far from the influence of the sea. In the interior, Calluna heaths exist on a small scale, especially on higher mountain peaks that are free of forests and that receive more rain than their surrounding area and are therefore more “Atlantic”. Many stands show hardly any other species apart from the heather that dominates the aspect; some acid-bearing grass species are common, e.g. B. Red ostrich grass ( Agrostis capillaris ) or wire smear ( Deschampsia flexuosa ). They are often rich in mosses and lichens, e.g. B. of the genus Cladonia . The widespread common heather itself shapes this type of vegetation almost completely, but is not suitable as a character species due to its wide distribution . Some species of gorse are used for this purpose, especially German gorse ( Genista germanica ) and English gorse ( Genista anglica ). But these are rare everywhere and only occur in the West. The scientific name for the association, "Genisto-Callunetum", is therefore somewhat misleading. After two other types of gorse, summer gorse ( Cytisus nigricans ) and head gorse ( Chamaecytisus supinus ), the rare and small-scale heaths of southern Germany are called "Cytiso-Callunetum". The most common type of gorse in the dwarf shrub heather is the broom ( Cytisus scoparius ). This occurs mainly in heaths of the western low mountain range, z. B. of the Sauerland, to dominance, but lack the pagans of the North German flatlands. Broom heaths are generally considered to be fallow and degenerative stages of Calluna heaths, which only emerge when they are no longer grazed.
Erica Pagans
Heaths with bell heather ( Erica tetralix ) occur on wet or damp locations , often in wet hollows within the Calluna heaths, but also naturally on the drier edge slopes ("lagg") of raised bogs , today more extensive on partially drained bogs, which is why one speaks from Moorheiden . Oberdorfer therefore places the Erica-Heiden among the raised bog peat moss societies (of the Oxycocco-Sphagnetea class). The distinctive and eponymous species of the "bell heather wet heather", the Ericetum tetralicis, is bell heather itself, Calluna vulgaris , but it is also common and frequent in this society. These species are accompanied by a number of rare, water-loving plant species such as rushing rush ( Juncus squarrosus ), leg breaker ( Narthecium ossifragum ), or turf rush ( Trichophorum cespitosum ).
Crowberry Heaths
In the coastal area and on the North Sea islands, mainly in windy places on fixed sand dunes, one finds the crowberry heather, which gets its name from the crowberry ( Empetrum nigrum ) that is widespread here . It also belongs to the dwarf shrub heaths. Crowberry heaths have their main distribution center in Northern Europe and only occur radiantly in Central Europe. Their species composition is very similar to that of the other heather societies, in addition there are many species of the dunes. A characteristic companion on the North Sea coast is the creeping willow ( Salix repens ).
Heather-like vegetation with crowberry also occurs in the high mountains above the alpine tree line, and here also mainly on hilltops exposed to the wind. These crowberry heather of the high mountains, however, forms another type of crowberry, Empetrum hermaphroditicum . The other plant species that occur are completely different from the crowberry heather in the coastal country. A characteristic companion is the dwarf juniper ( Juniperus communis var. Saxatilis ).
Dwarf shrub heaths in the mountains
In the highlands, the dwarf shrub heaths are mostly dominated by Vaccinium species such as bilberry ( Vaccinium myrtillus ) and lingonberry ( V. vitis-idaea ), in addition to common heather, which is also common here . Common companions such as bristle grass ( Nardus stricta ) and tormentil ( Potentilla erecta ) show the transition to bristle grass turf , with which they are almost always closely interwoven. In terms of vegetation, these mountain heaths are usually connected to the grass grass. Today mountain heaths have become even rarer than the heaths of the plains, the last stocks are mostly in the area of ski slopes.
Origin and location conditions
The dwarf shrub heaths originated in large areas through continuous grazing z. B. by sheep, on nutrient-poor, acidic sites. They were preceded by forests, either poor beech forests or beech-oak forests or, particularly often, the extremely nutrient-poor birch-oak forests . Grazing was certainly the decisive factor in the formation of heaths from forests. In addition, large areas were cleared for wood use. For the Lüneburg Heath u. a. blamed the immense need for firewood at the Lüneburg salt works. An economic system that had been well-established for centuries had developed in the north German heath economy. Their soils are actually too poor for continuous use of arable land once the forest's humus reserves have been used up. Therefore the pagans were "pounded" at regular intervals. H. the vegetation including the humus layer removed and applied to the much smaller fields (the "Esch") as fertilizer. In addition, the heather was regularly burned to preserve the pasture. Due to this unsustainable use ( overexploitation ), the classic heaths are extremely poor in nutrients. This often resulted in podsolization of the floors. Real podsols were mostly created under heather. If you find them under forests, this indicates a previous heather stage. The soil conditions can improve again on former heaths that are afforested or tree-covered by spontaneous reforestation.
Especially under heather on sand that is wet in the ground, the podsol under heather is sometimes so extreme that a rock-hard layer of local stone, colored red-brown by iron, can form at a depth of a few decimeters . In the Middle Ages, this was mined in many places as iron ore ("swamp ore"). When the pagans were cultivated, it was often necessary to break them open.
fauna
Dwarf shrub heaths usually have a fauna that is not particularly rich in species, but is highly characteristic, with numerous specialized species, some of which are now threatened with extinction due to the decline in heaths. The bird species woodlark and black grouse are particularly characteristic . Pita called as indicator species also wheatear , backed Shrike , Stonechat , tawny pipit , nightjar , Gray Shrike , all now red-listed species. Heath also serve as a habitat for many invertebrate species, such as B. Heide Schrecke ( Gampsocleis glabra ), the beetles Bradycellus ruficollis and Trichocellus cognatus , the bugs Nabis ericetorum and Eremecoris desertus , the heath leaf beetle ( Lochmaea suturalis , Chrysomelidae ) of heather-Sandbiene ( Andrena fuscipes ) of heather-Seidenbiene ( Colletes succinctus ) and many others. Many species are highly specialized in common heather as a habitat or food plant.
Existence and threat, nature conservation
Because of the abandonment of land use, afforestation, intensive fertilization and use as pasture or arable land, many heather areas have meanwhile disappeared. The centuries to millennia of traditional use (typical heather soils have been documented since the Bronze Age) is no longer profitable for agriculture under today's conditions. The remaining areas are also after their former use has been abandoned, partly due to encroachment, e.g. B. with gorse, and the emergence of forest trees (birches, pines, in the Lüneburg Heath also the neophytic late blooming bird cherry ( Prunus serotina )) at great risk. Another threat factor is unintentional fertilization by air pollution (rain enriched with nitrogen compounds from air pollutants), it leads to grazing of the heather. But even the lack of traditional use by pest management and grazing changes the heather, the common heather bushes age, become scruffy and eventually die off. "Dwarf shrub, gorse and juniper heaths" are therefore among the biotope types legally protected throughout Germany in accordance with Section 30 of the Federal Nature Conservation Act. According to the Habitats Directive of the European Union, "dry sandy heaths (of the dunes) with Calluna and Genista" (code 2310) and "dry sandy heaths (of the dunes) with Calluna and Empetrum nigrum" (code 2320), "humid heaths of the North Atlantic area with Erica tetralix "(Code 4010)," Dry European heaths "(Code 4030) and" Alpine and boreal heaths "(Code 4060) to the" natural habitat types of Community interest for whose conservation special protection areas must be designated "in Appendix 1 , so to the so-called Natura 2000 areas.
To preserve the heaths, the mere designation of protected areas as a sole measure is not yet sufficient. As use-dependent “semi-cultural formations”, they need traditional use or, where this is no longer possible or unprofitable, appropriate maintenance. By browsing sheep (mostly of the frugal traditional breed Heidschnucke ), the endangered biotope types are ensured in some areas. By Entkusselung the encroachment of the surfaces is prevented.
See also
literature
- Heinz Ellenberg : Vegetation of Central Europe with the Alps. From an ecological, dynamic and historical perspective (= UTB for science. Big series. 8104). 5th, heavily changed and improved edition. Ulmer, Stuttgart 1996, ISBN 3-8252-8104-3 .
- Franz Fukarek , Helmut Hübel, Peter König, Gerd K. Müller , Roland Schuster, Michael Succow : Vegetation . Urania, Leipzig 1995, ISBN 3-332-00550-2 , p. 269-271 .
-
Erich Oberdorfer (Ed.): South German Plant Societies. 2nd, heavily edited edition. Fischer, Stuttgart a. a .;
- Volume 1: Rock and wall communities, alpine corridors, water, silting and moor communities. 1977, ISBN 3-437-30260-4 ;
- Volume 2: Sand and dry grasslands, heather and bristle grass societies, alpine grasslands, fringing societies, perennial and perennial fields. 1978, ISBN 3-437-30282-5 .
Individual evidence
- ↑ NLWKN dwarf shrub and juniper heather
- ↑ Martin Flade: The breeding bird communities of Central and Northern Germany. Basics for the use of ornithological data in landscape planning. IHW-Verlag, Eching 1994, ISBN 3-930167-00-X (also: Berlin, Techn. Univ., Diss., 1993).
- ↑ Nature reserve "Former Siegschleife bei Dreisel"