Lake Chad flooded savanna

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Lake Chad flooded savanna
Kanal doprowadzajacy do jeziora - Jezioro Czad - 001269s.jpg
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location of the Lake Chad flooded savanna
Ecology
Realm Afrotropical
Biome flooded grasslands and savannas
Borders Sahelian Acacia savanna and West Sudanian savanna
Geography
Area31,988 km2 (12,351 sq mi)
Countries Cameroon, Chad, Niger and Nigeria
Conservation
Conservation status Critical/endangered
Protected14,732 km² (46%) [1]

The Lake Chad flooded savanna is a flooded grasslands and savannas ecoregion in Africa. It includes the seasonally- and permanently-flooded grasslands and savannas in the basin of Lake Chad in Central Africa, and covers portions of Cameroon, Chad, Niger, and Nigeria.

Contents

Geography

Lake Chad is a large shallow lake, lying at the center of a large closed drainage basin, with no outlet to the sea. The Lake Chad basin has an area of 2,381,635 square kilometres (919,554 sq mi). The northern portion of the basin is arid or semi-arid, and the southern portion has a seasonally-dry savanna climate.

The flooded savannas surround the lake. The Chari and Logone rivers, which drain northwards from the highlands along the basin's southern edge, supply 95% of Lake Chad's freshwater. The Yobe River, which flows eastwards into the lake's northern end, contributes 2.5% of the lake's inflow. [2]

Despite having no outlet, Lake Chad has relatively low salinity. The saltier waters sink to the bottom of the lake, and drain northwards via underground conduits. The southern portion of the lake, which receives far more river inflow, is generally less salty than the northern portion. [2]

The ecoregion also includes the Hadejia-Nguru wetlands in northern Nigeria. These seasonal wetlands form at the confluence of the Hadejia the Jama'are rivers, part of the Yobe River system lying west of the lake. These wetlands expand to 6,000 km² during the rivers' late-August peak, with a water surface area of 2,000 km². [2]

The Lake Chad portion of the ecoregion is surrounded by the Sahelian Acacia savanna ecoregion, a belt of dry savanna which runs east and west across Africa south of the Sahara Desert. The Hadejia-Nguru wetlands are bounded by the West Sudanian savanna ecoregion.

Climate

The climate is tropical and dry, with 320 mm of annual rainfall on the lake. Rainfall is concentrated during the June through October rainy season. March to June is hot and dry, and the November through February winter months are dry and cooler. Evaporation exceeds precipitation during most months. [2]

Flora

The lake includes areas of open water and shallow-water reed beds. Common reed bed plants in the southern lake include Cyperus papyrus, Phragmites mauritianus , and Vossia cuspidata . Phragmites australis and Typha domingensis are more common in the saltier northern lake. Nile lettuce ( Pistia stratiotes ) is a floating plant that occasionally forms large beds across open-water areas. [2]

Vegetation in seasonally-flooded areas varies with the depth and duration of seasonal flooding. Yaéré grasslands are found in frequently-flooded areas at the southern end of the lake. Characteristic plants include Echinochloa pyramidalis, Vetiveria nigritana, Oryza longistaminata , and Hyparrhenia rufa . Where seasonal flooding is shallower and shorter duration, Trees and shrubs are present, ranging from savannas to woodlands, locally known ‘karal’ or ‘firki’. Acacia seyal is the predominant tree, with Acacia nilotica around depressions. An understory of grasses and shrubs grows 2 to 3 meters high, and includes Caperonia palustris, Echinochloa colona, Hibiscus asper, Hygrophila auriculata, Sorghum purpureosericeum , and Schoenfeldia gracilis . [2]

Fauna

The flooded grasslands and savannas are important habitat for water birds, including Palearctic migrants that over-winter here. The river prinia (Prinia fluviatilis) and rusty lark (Mirafra rufa) are resident birds which inhabit the Lake Chad flooded savannas and other wetlands in the Sahel. [2]

Threats

The lake has shrunk considerably in recent decades, becoming much shallower and smaller in extent.

Protected areas

A 2017 assessment found that 14,732 km², or 46%, of the ecoregion is in protected areas. [1]

Related Research Articles

Lake Chad Lake in Africa

Lake Chad is a historically large, shallow, endorheic lake in Central Africa, which has varied in size over the centuries. According to the Global Resource Information Database of the United Nations Environment Programme, it shrank by as much as 95% from about 1963 to 1998. The lowest area was in 1986, at 279 km2 (108 sq mi), but "the 2007 (satellite) image shows significant improvement over previous years." Lake Chad is economically important, providing water to more than 30 million people living in the four countries surrounding it on the central part of the Sahel. It is the largest lake in the Chad Basin.

Flooded grasslands and savannas

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Sudd Swamp in South Sudan

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California Central Valley grasslands Temperate grasslands, savannas, and shrublands ecoregion in California, United States

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Llanos Grassland

The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, savannas, and shrublands biome.

Inner Niger Delta Inland delta of the Niger River

The Inner Niger Delta, also known as the Macina or Masina, is the inland delta of the Niger River. It is an area of fluvial wetlands, lakes and floodplains in the semi-arid Sahel area of central Mali, just south of the Sahara desert.

Humid Chaco

The Humid Chaco is tropical grasslands, savannas, and shrublands ecoregion in South America. It lies in the basin of the Paraná River, covering portions of central Paraguay and northern Argentina, and with a small portion of southwestern Brazil and northwestern Uruguay. The natural vegetation is a mosaic of grasslands, palm savanna, and forest.

Hadejia-Nguru wetlands

The Hadejia-Nguru wetlands in Yobe State in northern Nigeria, which include Nguru Lake, are ecologically and economically important. They are threatened by reduced rainfall in recent years, a growing population and upstream dam construction.

Waza National Park National park in Cameroon

Waza National Park is a national park in the Department of Logone-et-Chari, in Far North Region, Cameroon. It was founded in 1934 as a hunting reserve, and covers a total of 1,700 km2 (660 sq mi). Waza achieved national park status in 1968, and became a UNESCO biosphere reserve in 1979.

Articles related to Nigeria include:

East Sudanian savanna

The East Sudanian Savanna is a hot, dry, tropical savanna ecoregion of Central and East Africa.

Malagarasi River

The Malagarasi River is a river in western Tanzania, flowing through Kigoma Region, although one of its tributaries comes from southeastern Burundi. The river also forms the western border of Tabora Region, the southern border of Kagera (region) and the southwestern border of Geita Region. It is the second-longest river in Tanzania behind the Rufiji—Great Ruaha, and has the largest watershed of any river flowing into Lake Tanganyika. The Malagarasi-Muyovozi Wetlands are a designated a Ramsar site. Local tribes have nicknamed the Malagarasi as "the river of bad spirits".

Zambezian flooded grasslands

The Zambezian flooded grasslands is an ecoregion of southern and eastern Africa that is rich in wildlife.

Jamaare River

The Jama'are River, also known as the Bunga River in its upper reaches, starts in the highlands near Jos, Plateau State, Nigeria and flows northeast through Bauchi State and Yobe State before joining the Hadejia River to form the Yobe River. There has recently been controversy over a plan to build the Kafin Zaki Dam on this river, with concerns over the effect on seasonal flooding and the water table.

Tiga Dam

The Tiga Dam is in Kano State in the Northwest of Nigeria, constructed in 1971–1974. It is a major reservoir on the Kano River, the main tributary of the Hadejia River.

Zambezian coastal flooded savanna

The Zambezian coastal flooded savanna is a flooded grasslands and savannas ecoregion in Mozambique. It includes the coastal flooded savannas and grasslands in the deltas of the Zambezi, Pungwe, Buzi, and Save rivers.

Mulga Lands

The Mulga Lands are an interim Australian bioregion of eastern Australia consisting of dry sandy plains with low mulga woodlands and shrublands that are dominated by Acacia aneura (mulga). The Eastern Australia mulga shrublands ecoregion is coterminous with the Mulga Lands bioregion.

Chad Basin National Park

The Chad Basin National Park is a national park in northeastern Nigeria, in the Chad Basin, with a total area of about 2,258 km2. The park is fragmented, with three sectors. The Chingurmi-Duguma sector is in Borno State, in a Sudanian Savanna ecological zone. The Bade-Nguru Wetlands and Bulatura sectors are in Yobe State in the Sahel ecological zone.

The Yaéré, from Fula yaayre, is the name of a vast annually-flooded grassland and savanna, part of the extensive floodplains around the shallow and variable Lake Chad in Central Africa. The Yaéré is part of the Lake Chad flooded savanna ecoregion.

Chad Basin Largest endorheic basin in Africa, centered on Lake Chad

The Chad Basin is the largest endorheic basin in Africa, centered on Lake Chad. It has no outlet to the sea and contains large areas of semi-arid desert and savanna. The drainage basin is roughly coterminous with the sedimentary basin of the same name, but extends further to the northeast and east. The basin spans eight countries, including most of Chad and a large part of Niger. The region has an ethnically diverse population of about 30 million people as of 2011, growing rapidly.

References

  1. 1 2 Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b.
  2. 1 2 3 4 5 6 7 "Lake Chad flooded savanna". Terrestrial Ecoregions. World Wildlife Fund. Accessed 7 July 2020.