Raw sea
| Raw sea | ||
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| Black alders in the northern part of the Rohsees when the water level is low | ||
| Geographical location | Frankfurt am Main , Hessen , Germany | |
| Tributaries | Groundwater, rainwater | |
| Drain | Kelster (Main), evaporation | |
| Data | ||
| Coordinates | 50 ° 4 '34 " N , 8 ° 33' 3" E | |
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particularities |
The pool shows repeated periods of desiccation |
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The Rohsee, sometimes also called Rohrsee or Rodsee , is a still water in the southwest of the Hessian city of Frankfurt am Main . The very shallow body of water, fed by groundwater and rainwater, is an orographically left, geographically eastern or southern oxbow lake of the river Main . Archaeological finds in the vicinity of the lake indicate human settlement in the area in the Bronze Age and late antiquity . The Rohsee is the only naturally formed still water in the Frankfurt city forest .
Location and characteristics
As a river oxbow, the Rohsee has a very narrow, elongated floor plan in an approximately straight, south-southwest / north-northeast orientation. According to inland water science ( limnology ), it is a forest pond that turns into a swamp .
The body of water is located on the northwestern edge of the Frankfurt city forest in the area of the Schwanheim district . It is part of the conservation area of the Frankfurt green belt . The water level of the raw lake is subject to strong seasonal fluctuations; Depending on the groundwater level, the water is temporarily almost dry. This drying up was first mentioned in a chronicle from 1474; the most recent phase of drying out, lasting several years, occurred in the 1970s.
At its southern end, the Rohsee merges seamlessly into the Riedwiese marshland , along the southern edge of which the Kelster brook flows . Since the water level fluctuates and the transition between Rohsee and Riedwiese cannot be clearly identified, the cartographic representations of the area vary. In some official maps, the Rohsee and Riedwiese are drawn as one body of water, others show both separately. The representation of the stream of the Kelster, which is immediately adjacent and a few meters east of the Rohsees in a further swamp, varies from map to map.
Since 2003, the forest area on the Rohsee has been classified as a fauna and flora habitat according to the FFH guidelines of the EU .
Flora and fauna
The Rohsee is one of the most species-rich still waters in Frankfurt. According to a census carried out in 2006, the bank vegetation shows 44 different species of higher plants. In terms of vegetation, the raw lake is predominantly an alder break forest on wet moorland . The predominant tree species is the black alder ( Alnus glutinosa), tree of the year 2003, which thrives particularly well on wet to flooded soils because it has a very moisture-resistant wood. A special feature of the alder population in the Rohsee are its rhizomes ("stilt alder" or "stilt root alder"), which are exposed at low water and drought, and are said to be very old. This form of the rhizomes was created through centuries of deforestation, repeated at intervals of about 100 years, after which the rhizomes were repeatedly cut and new trunks formed. An age of the rhizomes of more than 1000 years is believed to be possible. The Schwanheim doctor and naturalist Wilhelm Kobelt wrote about the Rohsee in 1913:
“ Strange root formations protrude from the shallow water and its surroundings, which only merge into a number of weak alder stalks at a height of about one meter and at the transition point form a ledge that mostly carries moss and ferns ... A true picture of the swamps that existed in Roman times filled large areas of Germany. "
In addition to the prevailing black alder, the tree species are most Rohsee silver birch ( Betula pendula ) and in the shrub layer of alder buckthorn ( Frangula alnus encountered). There are also several very old specimens of the winter lime tree ( Tilia cordata ) on the Rohseeweg , a few meters from the western edge of the water . Other plant species found by and in the Rohsee are the water feather ( Hottonia palustris ), which has its last natural occurrence there in Frankfurt, the marsh iris ( Iris pseudacorus ), which is particularly protected in Germany , and the marsh marigold ( Catha palustris ), which has become rare in Frankfurt ). In the summer months in Rohsee and Riedwiese bloom duckweed ( Lemna ), which seem to be by their vegetation density of the surface of the water a bright light green color (see photos above right).
Archaeological finds
Bronze Age excavations
The southern bank of the Main Altarm, which later formed the Rohsee, was settled in the Bronze Age. This was evidenced by traces of settlement in the area of the directly adjacent Riedwiese, which were discovered in 1973 during excavations by the Heimat- und Geschichtsverein Schwanheim eV . Among other things, Bronze Age ceramics, a grinding stone used to grind grain and part of a clay spoon were found. Also found constructions made of tree trunks and set stones are interpreted as former bank fortifications. It is assumed that the Bronze Age settlement on the main arm of the Main was an outpost of the larger settlement from the same era, a short distance south of it on the Kelsterbach terrace in the parcel In der Wanz .
Roman fountain
A few meters west of Rohsee and Riedwiese, the remains of a stone-set Roman fountain were also found in 1973. To be dated to the 5th century AD. In the 3.80 meter deep well shaft, ceramic, glass and leather remains (a total of over 2000 fragments of vessels), a Roman denarius and a Roman clay plate were found. The clay plate bears the stamp of the Roman Legio XXII Primigenia, stationed in Mogontiacum (later the city of Mainz ) from 92 AD to the middle of the 4th century .
The main find from the well shaft is a human skeleton , which is also dated to late antiquity. The Anthropological Institute of the Goethe University in Frankfurt classified the skeleton as the remains of a young man in his early 20s who came from the eastern Mediterranean region and who had died as a result of violence (skull injury from a sword blow). The pathological examination of the skeleton revealed that the young man had done heavy physical labor from an early age. From this it was concluded that it was possibly a slave of the nearby Villa rustica . Remnants of the foundations of this Roman manor are almost 100 meters southwest of the well. The destruction of the manor in the course of the Alemanni storm in the 3rd century is believed to be possible. Some of the objects also found in the well - the sandstone sculpture of a bull and the incisors of several horses - are interpreted as evidence of a special burial. There was speculation about a human sacrifice by the Celts . The finds from this archaeological excavation now form the core of the collection at the Schwanheim Local History Museum.
After the excavations were completed, the well shaft was filled with earth; only the approximately 30 centimeter high natural stone fountain ring is still visible. The Roman path was named after the archaeological finds . It is an unpaved forest path that, starting from the southern outskirts of Schwanheim, follows the course of Bundesstraße 40 in a western and southern direction on the extreme western edge of the Frankfurt city forest . The Römerweg leads at the northern end of the Rohsees and directly past the Römerbrunnen in an arch to the foot of the Kelsterbacher Terrasse to the south.
Transport links
The Rohsee is somewhat isolated in the westernmost bulge of the Frankfurt city forest. Only its northern tip can be reached directly on foot or by bike. South of the Rohsee, the Wanzenschneise forest path (named after the In der Wanz parcel crossed ) leads along a narrow dam called the Schafbrücke over the Riedwiese wetland . The approach to the western bank up to a few meters is only possible on foot via the Rohseeweg that runs along it. On the eastern edge, any access is prevented by a dense belt of reeds ( reed beds ). To reach the area by motor vehicle, a walk of one kilometer (individual traffic) to two kilometers (local public transport) is required to get to the Rohsee. The last section is accessed via unpaved forest paths, which, depending on the weather, can have a softened, muddy surface.
Tram lines 12 and 19 as well as bus lines 62 and 73V of the Frankfurt transport company VgF operate at the Rheinlandstraße stop , which is closest to the Rohsee . The distance from the stop to the Rohsee is about two kilometers. The closest parking facilities for motorized private transport are at the western end of Rheinlandstrasse; from there it is about a kilometer by foot to the northern tip of the lake. Another two parking spaces are on Schwanheimer Bahnstrasse, also around two kilometers from the Rohsee.
literature
- Gerd-Peter Kossler (ed.) And other authors: Forest in the south of Frankfurt: Stadtwald, Gravenbruch, Mönchbruch. In it: Chapter Schwanheim Forest. S. 59 ff. Self-published, Frankfurt am Main 1991. ISBN 3-9800853-2-5 .
- Magistrate of the City of Frankfurt am Main, Environment Agency (ed.): City waters - lakes, ponds, ponds. In it: Chapter Rohsee. P. 59. Frankfurt am Main, 2003.
- Environment Office of the City of Frankfurt am Main (ed.): GrünGürtel-Freizeitkarte. 7th edition, 2011.
- Various authors: Nature on the doorstep - urban nature in Frankfurt am Main. Results of the biotope mapping. Kleine Senckenberg-Reihe 50, E. Schweizerbart'sche Verlagsbuchhandlung (Nägele and Obermiller), Stuttgart 2009, ISBN 978-3-510-61393-9 .
Web links
- Rohsee at par.frankfurt.de , the former website of the city of Frankfurt am Main
Individual evidence
- ↑ a b c d Environment Office of the City of Frankfurt: Stadtgewässer, p. 59: Rohsee.
- ↑ a b Kleine Senckenberg-Reihe 50: Nature on the doorstep. In it: Chapter still waters - biotopes made by human hands. P. 139.
- ^ City of Frankfurt am Main, Environment Agency (ed.): Stadtgewässer, enclosed city map on a scale of 1: 22,000.
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^ City of Frankfurt am Main, Forestry Office / City Survey Office (ed.):
Stadtwald Frankfurt a. Main. Map on a scale of 1: 20,000, Frankfurt am Main, 1888. - ↑ a b c d City of Frankfurt am Main, Environment Agency (ed.): GrünGürtel-Freizeitkarte.
- ↑ a b Rohsee at par.frankfurt.de , the former website of the city of Frankfurt am Main (accessed on October 4, 2011)
- ↑ Kleine Senckenberg-Reihe 50: Nature on the doorstep . In it: Chapter still waters - biotopes made by human hands , p. 79 f .: Rohsee.
- ↑ a b Kleine Senckenberg-Reihe 50: Nature on the doorstep . In it: Chapter forest - Frankfurt's shrinking lungs, p. 112.
- ↑ a b Kossler: Forest in the south of Frankfurt, p. 60 ff .: Rohsee.
- ^ Gerd-Peter Kossler: Forest in the south of Frankfurt. P. 60.
- ^ A b Association 1100 Years of Schwanheim eV (Ed.): 1100 Years of Schwanheim - A festival book for the 1980 anniversary year of the Frankfurt district of Schwanheim, p. 11 f.
- ↑ City of Frankfurt am Main, Forestry Office (ed.): Historischer Wanderweg Schwanheim - Wanderweg zur Schwanheimer history and prehistory . Therein: Chapter Riedwiese, p. 41. Third, corrected edition, Frankfurt am Main 2002.
- ↑ a b Heimat- und Geschichtsverein Schwanheim e. V. (Ed.): Heimatmuseum Schwanheim . Museum leaflet, without date.
- ↑ a b City of Frankfurt am Main, Forestry Office (Hrsg.): Historischer Wanderweg Schwanheim - Wanderweg zur Schwanheimer history and prehistory . Inside: Chapter Roman stone fountain from the 2nd / 3rd centuries Century on the site of a Roman court estate. Pp. 45 ff. Third, corrected edition, Frankfurt am Main 2002.
- ↑ Heimat- und Geschichtsverein Schwanheim eV (Ed.): Folder Heimatmuseum Schwanheim.
- ^ City of Frankfurt am Main, Forest Office / Protection Association of German Forest , District Association Frankfurt eV (Ed.): From Altheeg to Vierherrnstein - names in the Frankfurt city forest. P. 45. Frankfurt am Main, 1988.
- ↑ Access to the Rohsee at par.frankfurt.de , the former website of the City of Frankfurt am Main (accessed on October 4, 2011)