Boundaries

This ecoregion is defined by the upper Niger River basin above the Inner Niger Delta [508] and lies primarily within the countries of Guinea and Mali, with smaller portions in Burkina Faso and Côte d\'Ivoire. High rainfall in the Fouta Djalon and central Guinean highlands feed the steep, fast-flowing rivers and streams of the Upper Niger ecoregion (Welcomme 1986). 

Topography

The Niger\'s source is located 240 km from the Atlantic Ocean, on the landward side of the Fouta Djalon highlands (John 1986). At an altitude of 1,000 m asl the Niger (as the River Tembi) emerges from a deep ravine, from which it descends through rocky stretches with rapids and waterfalls (Lowe-McConnell 1985; John 1986). In Mali, the Niger cuts through the Manding Plateau (760 m asl), an extension of the Fouta Djalon Mountains (Hughes & Hughes 1992). In the northeastern corner of the ecoregion, it flows through 60 km of steeply descending rapids (Beadle 1981). As the slope of the land declines, the river slows and widens and to the point where it enters the vast floodplains of the Inner Niger Delta [807]. From its headwaters to the inner delta, the upper Niger flows for a total of about 750 km and drops approximately 300 m in altitude over its course (Welcomme 1986). 

Freshwater habitats

Because the upper Niger flows over weathered and strongly leached pre-Cambrian rocks, its water is relatively clear with a low sediment load (Rzóska 1985). As it flows into Mali, the river becomes broad and studded with islands (Hughes & Hughes 1992). Headwater tributaries begin to flood in May with a peak in September (Welcomme 1986). Downstream, these waters flow into the Inner Niger Delta [807] and inundate the inner delta floodplain, with a total influx of water from the upper Niger of 73 km³ per year (Welcomme 1986). 

Terrestrial habitats

The upper Niger and its tributaries flow through a mix of woodland and savanna. The headwaters in Guinea drain transitional savanna intermittent with large bands of deciduous and semi-deciduous gallery forest (Hughes & Hughes 1992). Further downstream in Mali, the Niger and Bani Rivers flow through tropical lowland moist forest, which shifts to dry grassland as the rivers approach the inner delta (Welcomme 1986). 

Description of endemic fishes

The only endemic cichild in the Niger River, Gobiocichla wonderi, has a small, elongated body that is well suited for taking refuge from the current in crevices between rocks along the bottom of the streams (Lowe-McConnell 1985; Lévêque et al. 1991). 

Justification for delineation

The upper Niger probably flowed into the Senegal River during the Pliocene and Early Pleistocene. This connection would account for similarities between the fish faunas of the two rivers (Lowe-McConnell 1985). The dry period following the early Pleistocene produced sand dunes that barred flow to the Senegal and diverted it to the basin west and northwest of Tombouctou (Beadle 1981). The upper Niger has followed its current course since the Pleistocene, although flow has been interrupted during dry periods (Lowe-McConnell 1985).

Level of taxonomic exploration

Good