This plant is not native to Africa, but only from Australian continent. I checked other sources, and found references to "Hardy, drought-resistant acacia trees now dig their roots into 330 miles of northern Senegal's Tessekere-Widu rural region. Planting began in 2008."
What are the dangers of planting a foreign tree monoculture without importing the wildlife that supports them? Why didn't they use a native African tree?
The German Acacia Wikipedia entry only contains the genus Acacia, while "Akazien" points to the tribe that is including all those plants that are normally known under the common name of acacia.
Btw, the picture of the English wikipedia also shows that the genus Acacia is only native to Australia. I guess they are planting Senegalia and not Acacia there. Same plant, it just got renamed 10 years ago.
The goal of reforestation in drylands is to increase shade to reduce evaporation. Once the acacia has provided enough quick shade they can (and hopefully will) plant other plants in the understory to increase diversity.