Spatial patterns of aridity and vegetation in West Africa

 

    Source: Sanusi, A. (2026)

The map presents West Africa with clear contrasts in relief, vegetation cover, and climatic zones. Two major ecological belts dominate the region; a humid vegetated zone along the southern coast and a semi-arid to arid zone toward the north. These belts broadly follow a south-north gradient controlled by rainfall, temperature, and distance from the Atlantic Ocean.

Regional spatial pattern

Southern West Africa, especially the coastal and forest belt, is shown in green. This zone extends from Guinea through Sierra Leone, Liberia, Côte d’Ivoire, Ghana, Togo, Benin, and southern Nigeria. It reflects high rainfall, dense forests, wetlands, and productive agricultural land.
In contrast, the northern part of the region transitions into yellow and light brown tones, indicating semi-arid conditions. This Sahelian belt stretches from Mauritania and Mali through Burkina Faso and Niger, with limited vegetation and strong exposure to drought. The Atlantic Ocean along the west and south moderates climate and supports dense vegetation near the coast.

Country by country ecological analysis

Mauritania
Mauritania lies almost entirely within the semi-arid to arid zone. Vegetation is sparse, confined mainly to river valleys such as the Senegal River in the south. It is one of the most environmentally stressed countries due to desert conditions and land degradation.

Mali
Mali shows a strong north-south contrast. The northern half is semi-arid to arid with minimal vegetation, while the southern zone has savanna vegetation supported by seasonal rainfall. The country is highly affected by drought and desert expansion.

Niger
Niger is dominated by semi-arid conditions, especially in the north and center. Vegetation is very limited, with some greener zones only in the southern margin near Nigeria. Niger is among the most affected countries by aridity and climate stress.

Burkina Faso
Burkina Faso lies mainly within the Sahelian and northern savanna zones. Vegetation is moderate but fragile. Semi-arid conditions dominate the north, while the south has better vegetation. The country faces frequent droughts and land degradation.

Senegal
Senegal shows good vegetation cover along the south-north gradient. while the southern Casamance region is greener with higher vegetation cover. Environmental stress is moderate but increasing in the north.

The Gambia
The Gambia is largely vegetated due to the influence of the Gambia River. It lies mostly within the savanna zone and is less affected by semi-arid conditions compared to its neighbours.

Guinea and Guinea-Bissau
Guinea Bissau is largely covered by dense vegetation. High rainfall supports forests and wetlands. While Guine Conakry is affected with Semi-arid zones along the South-north gradient, but with little vegetation along the coast.

Sierra Leone and Liberia
Both countries are strongly vegetated with tropical forests along the coast and inland. They experience minimal semi-arid influence and have favourable ecological conditions, though they are vulnerable to deforestation.

Côte d’Ivoire
Côte d’Ivoire shows dense vegetation in the south and savanna in the north. Semi-arid conditions are limited to the far north. Overall, ecological conditions are relatively stable.

Ghana
Ghana has a clear ecological gradient. The south is forested and well vegetated, while the north transitions into savanna and semi-arid conditions. Northern Ghana is more affected by drought and vegetation loss.

Togo and Benin
Both countries are narrow and show strong north-south contrasts. Southern areas are humid and vegetated, while northern areas fall within the semi-arid savanna zone. Northern regions are more vulnerable to climate stress.

Nigeria
Nigeria shows significant ecological diversity. The southern region is highly vegetated with forests and wetlands. Central Nigeria is savanna, while the far north is semi-arid. Northern Nigeria is among the most affected zones due to drought and desertification.

Most affected countries

Based on the extent of semi-arid zones and limited vegetation, the most affected countries are Mauritania, Niger, Mali, Burkina Faso, and northern Nigeria. These countries lie largely within the Sahel and face high vulnerability to drought, land degradation, and desert expansion. In contrast, coastal and forest-zone countries experience fewer impacts from aridity but face other pressures such as deforestation and land use change.

In synopsis, the map highlights a clear ecological divide in West Africa, with environmental stress increasing steadily from the humid southern coast toward the dry northern interior.

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