Exotic Acacia species in Zimbabwe: a historical and ecological perspective.
The present study investigated the history, occurrence, geographical distribution and invasiveness of the exotic Acacia species in Zimbabwe using herbarium and literature records. At least 17 Acacia species originating from Australia were introduced to Zimbabwe, with nine species (52.9% of total) documented as casuals, naturalized or invasive. Acacia mearnsii and A. melanoxylon were recognized as invasive, A. dealbata, A. decurrens, A. elata and A. podalyriifolia as naturalized, and A. baileyana, A. longifolia and A. salicina as casuals. All nine exotic Acacia species were introduced as ornamentals, A. dealbata, A. decurrens and A. mearnsii were also introduced for tanbark, and A. longofolia, A. mearnsii and A. melanoxylon were also introduced for timber. The majority (88.9%) of exotic Acacia species were introduced in the eastern part of Zimbabwe, a region characterized by tropical to semi-temperate climate, which is similar to the areas of origin of Acacia species.