The History, Impacts And Control OF Introduced Species In The Kruger National Park, South Africa

Summary

The environment and history of this 19 485 km² tropical and subtropical savanna national park are described. The growth in awareness of the problems posed by alien organisms is documented: protected since 1898 and proclaimed as a national park in 1926, the first major policy decisions and control programmes for introduced species were initiated in the 1950s. Eight introduced pathogenic micro-organisms, 113 higher plants, two molluscs, one ant, one fish, one bird and two mammals have become ‘invasive’ in the Park. Only the micro-organisms and seven of the higher plants (comprising three floating aquatic macrophytes, one tree, one shrub, one cactus and one herb) are considered to have serious ecological impacts on the Park. The control programmes that have been carried out are described: seven of 25 invasive species of trees and shrubs and three of 88 plant species of other growth forms have been eliminated. With current technology, control is considered feasible for a further 13 and one species respectively. Intentional and accidental introduction by man and water-borne dispersal into the Park down the major influent rivers are all of major importance. Infestations of introduced plants are negligible in the frequently fired savanna vegetation while the rivers, riverbeds and riverine fringe have heavy infestations. Fire and ungulate herbivory are considered important factors limiting plant invasions. Control of certain introduced plant species along these rivers has proven to be difficult if not impossible, and the growth in the allocation of manpower and funds to these control programmes is documented. The importance of devising effective control strategies for these water-dispersed species is stressed.