The African Acacias - a thorny subject
Abstract: There are 155 Acacia species in Africa - including 5 hybrids. They are intermediate in plant succession and colonize degraded land. They restore fertility and can be maintained indefinitely in agricultural systems. They provide many benefits but are disliked for their thorns and invasiveness. Seed was collected across the ranges of Acacia erioloba, A. karroo, A nilotica, A.senegal, A. tortilis and Faidherbia (formerly Acacia) albida. Screening trials indicated that, with selection, all had potential both inside and outside their natural ranges. Subsidiary studies showed that some acacias obtain their nitrogen from groundwater rather than from the atmosphere, that they can produce more crude protein per hectare than a grain crop, that there are annual rings in the wood, and that gum arabic could be a lucrative cash crop. Farmers will resist planting acacias until the benefits can be translated into cash. The challenge for breeders in the new millennium is to produce trees that are inherently so good that they sell themselves to the farmer.
Dry woodlands of Africa South of the Sahara
A. L. GRIFFITH
Silviculturist, East African Agricultural and Forestry Research Organization, Kenya