Boundaries

This expansive ecoregion comprises the plateaus and lowlands of the Central European Plain. Encompassing more than 15 countries it stretches from England and the Atlantic coast of France in the west to Lithuania and Belarus in the east, and from Denmark in the north to France and Switzerland in the south. It is delimited by the North and Baltic seas in the north and the Alps and Carpathian Mountains in the south.

Topography

This broad landscape stretches from the flat to gently rolling lowlands of the Central European Plain (which extends to southern England) to the hills, deep valleys, and mountains of the central uplands and plateau, and then to the deeply cut valleys, steep mountains, and rugged peaks of the Alps and Carpathians. Elevations range from sea level to more than 4000 m asl, with mean elevations of around 200 m asl (Hijmans et al. 2004). Some of the highest peaks include the Mont Blanc (4810 m asl), the Matterhorn (4478 m asl), Täschhorn (4491 m asl), Dom (4545 m asl), and Weisshorn (4504 m asl). The Sudede Mountains (highest peak Sněžka, 1602 m asl) and the Carpathian Mountains/Tatras (highest peak Rysy at 2503 m asl in Poland, and Gerlach Peak at 2655 m asl in Slovakia) form the southeastern border. The landscape was formed through uplift and rift formation during the Alpine orogeny as well as multiple glaciations (Uehlinger et al. 2009).

Freshwater habitats

This ecoregion encompasses the major drainage basins of the North European Plain in Western Europe. It includes the British Isles’ Severn, Thames, Ouse, Trent, and Mersey, as well as continental rivers such as the Loire, Seine, Meuse, Rhône, Rhine, Weser, Elbe, Oder, Vistula, and Nemunas. Many of these rivers have experienced modifications for centuries. Today, eutrophication and nitrate deposition pose the greatest challenge, although the quality has improved in many rivers in recent decades (Tockner et al. 2009). Most of the large rivers have lost between 70 to 90 percent of their former floodplains. This ecoregion also contains some of Central Europe’s most notable alpine lakes, including Lake Geneva (Lac Léman), Lake Neuchâtel, Lake Constance, Lake Lucerne, and Lake Zürich.

The Severn (354 km) is the longest river in the UK. Rising in the eastern slopes of Plynlimon, it flows through long meandering sections before emptying into the Severn estuary, the second largest tidal estuary in the world. Its mean flow is 106.3 m³/s. The Thames has an even larger catchment, and also flows into an extensive tidal estuary at a mean flow rate of 65.5 m³/s. Following these are the rivers Ouse and Trent, which together drain 20% of the land area of England. Rising in the Pennines, these two rivers flow into the Humber estuary with a resulting mean discharge of 250 m³/s (Soulsby et al. 2009).

Continental Atlantic rivers include the Loire, Charente, Seine, and Meuse. The Seine, one of the largest rivers in France, has lost more than 99% of its former riparian floodplains, the highest impact in Europe (Tockner et al. 2009). The Loire and Charente, by contrast, retain a more natural character although they have also experienced high anthropogenic changes. The longest of these, the Loire, flows 1012 km from the Massif Central through narrow valleys and vast alluvial plains to the Atlantic Ocean. The Loire, and its most important tributary the Allier, is characterized by gorges in the upper part, islands, braided reaches, meanders, and floodplains in the middle and lower part. Because of navigation since the 19^th Century, discharge dynamic is still shaping the river and floodplain morphology in some river stretches. It also includes large sand banks and gravel bars, fens, swamps, ponds, lakes, floating forests, flooding meadows, and marshes. Its annual discharge is 869 m³/s, with maximum flow occurring in winter and minimum flow in July-October (Descy 2009).

The Rhône is the only river in the ecoregion that flows to the Mediterranean Sea. This ecoregion includes the upper portion of the Rhône to the confluence with the Isère. It originates from the Furka Glacier in Switzerland and drains steep headwaters before flowing into Lake Léman. This upper and middle portion flows through gorges, braids, and alluvial plains before reaching the confluence with the Isère (Olivier et al. 2009). The lower part is heavily modified by channelization and impoundments. The Delta itself, the Camargue, despite strong anthropogenic impacts from water engineering and farming, contains remnants of a very rich biodiversity.

Encompassing nine countries in a drainage area of around 185,000 km², the Rhine is the ninth largest river in Eurasia and the only north-flowing Alpine river. It stretches 1250 km with a mean annual discharge of 2300 m³/s. The two main headwaters are the Vorderrhein and Hinterrhein, which merge to form the Alpine Rhine that flows into Lake Constance. The Rhine historically was characterized by gorges, braids, meanders, rapids, sandbars, oxbow lakes, and floodplains. Much of the Rhine and most of its tributaries like the Neckar, Main, Mosel and Lippe, however, have been significantly modified for navigation and regulated by impoundments. Within the catchment most rivers have lost their natural floodplains due to land claims for intensive agriculture, settlement and infrastructure development. It meets the Meuse and Scheldt at the Rhine Delta, which historically was an extensive estuary composed of islands, peninsulas, tidal channels, intertidal sand and mudflats, as well as salt and brackish marshes (Uehlinger et al. 2009). The Rhine itself is considered to be the most navigated European inland waterway.

Some of the rivers along the central European highlands and plains that flow into the Baltic and North seas include the Ems, Weser, Elbe, and Oder. Much of this region was affected by a large ice cap of the Weichsel Glacial period, creating moraines, different types of glacial lakes, glacial valleys, and plains with glaciofluvial deposits. Typically, there is seasonal variation in flow in this region. Floods occur due to snow melt and rain in the headwaters in winter and early spring, although the Weser, Elbe, and Oder do experience major floods during the summer. The Elbe is one of the longest rivers in Central Europe, and still has a natural flow dynamic in the middle reach and active floodplains. The headwaters in the Czech Republic and a lot of the tributaries in the German catchment are regulated by impoundments. It flows through glacial valleys and floodplains, and in sections forms large meanders. Its total discharge into the North Sea is 870 m³/s. The Oder flows 854 km from the Sudety Mountains through lowlands to the Szczecin Lagoon at the Baltic Sea. The average discharge is 870 m³/s (Pusch et al. 2009). Because of land claims in the alluvial valleys for most of these rivers since the Middle Ages, between 70 and 90 % of floodplain loss has been documented (Brunotte et al. 2009). Nevertheless, the remaining active floodplains of large rivers in Central Europe (which include oxbow lakes, flooded forests and alluvial meadows) are an important part of the ecological network of conservation sites within the European Union (Natura 2000).

The Vistula and Nemunas (Nemans) are meandering, lowland rivers with extensive floodplains. The Vistula stretches 1068 km from the Beskid Mountains to the Baltic Sea. This lowland river’s slope is 1 m//km and its mean annual discharge is 1060 m³/s, with high interannual variation. The central and northern parts of the basin are dotted by thousands of lakes and hillocks, which are remnants of former glaciers. The Nemunas travels 937 km from the Minsk Uplands to the Curonian Lagoon. It is a lowland river fed primarily by snowmelt (Timm et al. 2009).

An extensive number of Ramsar sites have been recognized across the ecoregion, including mires, bogs, marshes, springs, flooded forests, estuaries, lakes, and lagoons (Wetlands International 2002). Vast low-lying peatlands, particularly in the eastern part of the ecoregion, are a significant feature of this ecoregion by providing important habitats for waterfowl and various freshwater fauna (Minayeva et al. 2009). Other notable areas include the Biebrza Valley, which has one of the largest and most intact marsh in Central Europe, and the Masurian and Pomeranian lake districts, which are examples of moraine-dammed lakes that formed during and after the Pleistocene (IUCN 1993).

Terrestrial habitats

 This ecoregion spans much of the Atlantic and Continental biogeographic regions of Europe where deciduous oak, beech, and mixed beech forests were once common, as were floodplains, peatlands, marshlands, mires and bogs, which once covered vast expanses across Central Europe (Natura 2000; Succow and Joosten 2001). Today most of West and Central Europe has been transformed into arable land and near natural grasslands from urbanization that has occurred throughout the last 2000 years. The once extensive floodplains, forests, peatlands and grasslands, especially sub-montane and alluvial grasslands, have declined dramatically. However, remaining areas still provide important refuges for biodiversity. For example, important wetland areas still exist along the Danube, Po, upper Loire and Elbe rivers.

Description of endemic fishes

Nearly a third of the species in the ecoregion are strict endemics, and a number of others are restricted to two ecoregions. Strict endemics include species in the genera Coregonus, Salvelinus, and Cottus. Of these, approximately 80% of the endemics are in the genus Coregonus. Many of these species are restricted to alpine lakes and include the gravenche (C. hiemalis), formerly in Lake Geneva but now extinct; bondelle (C. candidus) in Lake Neuchâtel; and sandfelchen (C. arenicolus) in Lake Constance (Kottelat & Freyhof 2007).

Other noteworthy fishes

The European Atlantic sturgeon (Acipenser sturio) and American Atlantic sturgeon (A. oxyrinchus) have disappeared throughout the European waters along the North and Baltic seas (Debus 2004). In fact, one relict population of the critically endangered European Atlantic sturgeon remains in the Gironde-Garonne-Dordogne drainages (UICN et al. 2010). Recent efforts have been made to reintroduce the species to the Oder (A. oxyrinchus) and Elbe (A. sturio) rivers (Gessner et al. 2006). The apron (Zingel asper), another critically endangered species, was once widespread throughout the Rhône, but now occupies roughly 280 linear kilometers in the Durance basin due to habitat fragmentation (Freyhof & Kottelat 2008; Keith & Allardi 2004; UICN et al. 2010).

Ecological phenomena

Rivers of this ecoregion have historically supported migrating species, most notably the European Atlantic sturgeon (Acipenser sturio) and American Atlantic sturgeon (A. oxyrinchus) noted above. The Loire system, for example, is home to anadromous species such as the European river lamprey (Lampetra fluviatilis), Atlantic salmon (Salmo salar), sea trout (Salmo trutta), shad (Alosa alosa), twaite shad (A. fallax), Atlantic sea lamprey (Petromyzon marinus), smelt (Osmerus eperlanus), and the catadromous European eel (Anguilla anguilla) (Descy 2009). Most of these species, however, have significantly declined or become extinct in rivers like the Rhine and Elbe (Pusch et al. 2009; Uehlinger et al. 2009). The Zährte or Vimba (Vimba vimba) remains noteworthy as an indicator species in eastern lowland rivers because of its long-distance spawning migrations and the wide variety of habitats it encompasses.

Justification for delineation

Northern and eastern European ecoregions were delineated through a top-down process using major basins as a starting point and incorporating traditionally recognized zoogeographic patterns where appropriate (Abell et al. 2008). Endemic species of Salvelinus, Coregonus, and Cottus exist in the ecoregion (M. Kottelat pers. comm. Jan. 16, 2006).