Australian wattle species in the Drakenberg region of South Africa - An invasive alien or a natural resource

An investigation into the spread of two alien wattle species (Acacia mearnsii and Acacia dealbata) in rural parts of the Drakensberg region of South Africa and the importance of the trees to the livelihoods of the local communities was carried out. With the aid of aerial photography two plots near the village were selected. Wattle aerial cover increased from 7% and 20% in the two plots, respectively, in 1953, over 21% and 33% in 1975, to 48% and 58% in 2000. In 1995, a government-sponsored national programme, "Working for Water" was established, with the expressed purpose of employing people described as being from the poorest and disadvantaged rural communities to clear areas of invasive alien species from river catchments and water courses. Whilst the programme provides an income to thousands of families in rural areas, it may also be jeopardising the livelihoods of the same communities. The wattle is an important resource for village households; virtually all households used it as their primary heat source and for building materials. Other uses included medicine extraction and 20% of the interviewed households gained income from selling firewood. From the rural communities' perception, the greatest concern regarding the alien species is its high water consumption (although this did not affect them directly), and the fact that it provides cover to thieves and criminals. Consequently, most villagers wanted either a reduction of the wattle stands (58% and 86% in the 2001 and 2003 study, respectively), or that they remained as at present (42% and 10%, respectively). Leaves from woody legumes have demonstrated large potential as green manures and fodder providers in many agroecosystems. The abundance of the wattle in the study area suggested an exploration of alternative beneficial uses in the low input farming systems practiced. The wattle's potential as green manure was evaluated in a decomposition trial. In all treatments, the wattle litter immobilised nitrogen from soil, in spite of a high N content of the litter. Plant available P increased in soil after 4-5 months of incubation. We argue that the current practice of externally funded wattle control is not sustainable in the long term. We discuss alternative approaches with a higher level of community participation and ownership, and conclude that the current underutilization of land may, ironically, be one of the largest constraints for a viable solution to the spread of wattle.