In Nigeria, the Guinea savanna belt acts as a transition zone, bordering both the rainforests to the south and the Sudan savanna to the north. 

The Guinea savanna is a broad, transitional ecological zone that stretches across the middle of Nigeria, encompassing a significant portion of the country's land area. To the south, the Guinea savanna transitions into the dense, evergreen rainforests that characterize the coastal regions of Nigeria. As you move north, the Guinea savanna gives way to the Sudan savanna, which is characterized by shorter grasses and a more arid climate.