RESEARCH

THE PROBLEM

Invading alien plants (IAPs) are the single biggest threat to plant and animal biodiversity. IAPs have become established in over 10 million hectares of land in South Africa. The cost of controlling IAPs in South Africa is estimated at R600 million a year over 20 years. If IAPs are left uncontrolled, the problem will double within 15 years. IAPs waste 7% of our water resources; reduce our ability to farm; intensify flooding and fires; cause erosion, destruction of rivers, siltation of dams and estuaries, and poor water quality and can cause a mass extinction of indigenous plants and animals.

KEY STATISTICS:

750 tree species and 8 000 herbaceous species introduced into South Africa
1 000 introduced species are naturalised, 200 are invasive
84 species introduced from South and Central America
14 from North America
30 from Australia
29 from Europe
36 from Asia
45% of species from Australia have become important pests

WORKING FOR WATER-FUNDED RESEARCH

WfW Research Strategy [PDF - 304KB]

Hydrological:

• Prinsloo, F.W. and Scott, D.F. (1999). Streamflow responses to the clearing of alien invasive trees from riparian zones at three sites in the Western Cape Province. Southern African Forestry Journal 185: 1-7
• Le Maitre, D.C., Versfeld, D.B. and Chapman, R.A. (2000). The impact of invading alien plants on surface water resources in South Africa: A preliminary assessment, Water SA 26,3: 397-408.
• Larsen, E.J., Marais, C.M. and Görgens, AHM (2001). Water resources planning with recognition of alien vegetation eradication. In proceedings of 10th South African National Hydrological Symposium: 26 - 28 September, 2001. 11 pp.
• Fourie, F., Mbatha, K., and Verster, H. (2002). The Effect of Vegetation (Prosopis spp.) on Groundwater levels in Rugseer River, Kenhardt, South Africa, Unpublished Department of Water and Sanitation, 8 pp.
  
• Brown, C. A., Boucher, C., Pienaar, E. and Pemberton, C. (2004). Effects of alien invasives on the Breede River, Southern Waters, UWC & University of Stellenbosch, 69 pp.
• Everson, C., Moodley, M., Gush, M., Jarmain, C, Govender, M & Dye, P. (2005). Can effective management of riparian zone vegetation significantly reduce the cost of catchment management and enable greater productivity of land resources. WRC Report No. K5/1284. 49 pp.
• Dye, P, and Jarmain, C. (2004). Water use by black wattle (Acacia mearnsii): implications for the link between removal of invading trees and catchment streamflow response. South African Journal of Science 100: 40-44.
• Marais, C and Wannenburgh, A.M. (2008). Restoration of water resources (natural capital) through the clearing of invasive alien plants from riparian areas in South Africa - Costs and water benefits. South African Journal of Botany 74: 526-537.

Ecological:

• Euston-Brown, D. (2000). The influence of vegetation type and fire severity on catchment stability after fire: a case study from the Cape Peninsula, South Africa. 35 pp.
• Fourie, S., Fabricius, C. and Shackleton, C. (2002). An ecology research strategy for Working for Water. Rhodes University, 42 pp.
• Gibson, D. & Low, B. (2003). National invading alien plant survey inception report. SRK Consulting, Report No. 304201, 28 pp.
• Jayiya, T.P., Moses, A.G., Forsyth, G.G., and van Wilgen, B.W. (2004). The effects of invasion by alien shrubs and trees on the fuel properties of ecosystems in the Western Cape, South Africa, 27 pp.
• Milton, S.J. (2004). Grasses as invasive alien plants in South Africa, South African Journal of Science 100: 69-75.
• Samways, M.J. & Taylor, S. (2004). Impacts of invasive alien plants on red-listed South African dragonflies (Odonata), South African Journal of Science 100: 78-80
• Musil, C.F., Milton, S.J., and Davis, G.W. (2005). The threat of alien invasive grasses to lowland Cape floral diversity: an empirical appraisal of the effectiveness of practical control strategies. South African Journal of Science 100: 337-344.
• Mgidi, T. N., le Maitre, D.C., Nel, J., Rouget, M., Richardson, D.M., Midgley, C., Mdzeke, N., van Wilgen, B.W., Schonegevel, L., Henderson, L., Neser, S., and Egoh, B. (2005). An assessment of invasion potential of invasive alien plant species in South Africa. CSIR Report No. ENV-S-I-2004-108, 107 pp.
• Euston-Brown, D., Rathogwa, N & Richardson, D.M. (2007). Development of a clearing protocol based on ecological criteria for mesic savannas and sweet grassveld for the Working for Water programme. 86 pp.
• Holmes, P. (2007). Targets for ecosystem repair in riparian ecosystems in fynbos, grassland and savanna biomes. Cape Ecological Services, 42 pp.
• Henderson, L. (2007). Invasive, naturalized and casual alien plants in southern Africa: a summary based on the Southern African Plant Invaders Atlas (SAPIA). Bothalia 37,2: 215–248.
• Jovanovic, N.Z., Hon, A., Israel, S., le Maitre, D., Rusinga, F., Soltau, L., Tredoux, G., Fey, M.V., Rozanov, A.,  and van der Merwe, N. (2008). Nitrate leaching from soils cleared of alien vegetation. CSIR Natural Resources & Environment and University of Stellenbosch. WRC Report No. K51/1696

Resource economics:

• Marais, C., Turpie, J, Mullins, D., Conradie, B., Khan, A., Goldin, J., van Zyl, H., Grobbelaar, E., Vink, N., Ndzinge, V. (2001). A cost-benefit analysis framework for the national Working for Water Programme. 59 pp.
• De Witt, M.P., Crookes, D.J. and van Wilgen, B.W. (2001). Conflicts of interest in environmental management: estimating the costs and benefits of a tree invasion. Biological Invasions 3: 167-178
• van Wilgen, B. W., Richardson, D.M., le Maitre, D.C., Marais, C., and Magadlela, D. (2001). The economic consequences of alien plant invasions: examples of impacts and approaches to sustainable management in South Africa. Environment, Development, and Sustainability 3 :145-168.
• van Wilgen, B. W., de Wit, M.P., Anderson, H.J., le Maitre, D.C., Kotze, I.M., Ndala, S., Brown, B., and Rapholo, M.B. (2004). Costs and benefits of biological control of invasive alien plants: case studies from South Africa. South African Journal of Science 100: 113-122.
• Sowman, M. (2002). January 2000 fires (on the Cape Peninsula): An assessment of perceptions. Environmental Evaluation Unit, University of Cape Town, 30 pp.
• Du Plessis, L.L. (2003). An assessment of selected non-water benefits of the Working for Water Programme in the Eastern and southern Cape. MA thesis. Faculty of Arts, University of Port Elizabeth, 156pp.
• Hosking, S. G., and du Preez, M. (2004). A cost-benefit analysis of the Working for Water Programme on selected sites in South Africa. Water SA 30(2): 143-152.
• Allsopp, M., and Cherry, M. (2004). An assessment of the impact on the Bee and Agricultural industries in the Western Cape of the clearing of certain Eucalyptus species using questionnaire survey data. Plant Protection Research Institute, Agricultural Research Institute and AgriAfrica Consultants, 58pp.

Operational:

• KPMG (2001). An investigation into the potential for the development of secondary industries through the utilisation of biomass made available through projects aimed at the control of invasive alien plants, KPMG, Stellenbosch University & ENF: 106 pp.
• Breen, C., Erskine, J., Jelinek, E., Mbowa, S., Quinn, N. and Salomon, M. (1997). Evaluation of the Working for Water Programme for the Commission of the European Communities, Brussels & Government of South Africa, Department of Water and Sanitation. Ingenieurbüro für Landentwicklung, Florstadt, Germany in association with Institute of Natural Resources, University of Natal, Pietermaritzburg.
• Common Ground (2003). External evaluation of the Working for Water programme. Synthesis Report, Common Ground Consulting, 95 pp.
• Levendal, M.R., le Maitre, D.C., van Wilgen, B.W. and Ntshotso, P. (2008). The development of protocols for the monitoring and evaluation of benefits arising from the Working for Water Programme. CSIR Natural Resources and the Environment, Report No. CSIR/NRE/ECO/ER/2008/0066/C, 103 pp.
• van Wilgen, B.W., Forsyth, G.G., and le Maitre, D.C. (2008). The prioritisation of species and primary catchments for the purposes of guiding invasive alien plant control operations in the terrestrial biomes of South Africa. CSIR Natural Resources and the Environment Report No. CSIR/NRE/ECO/ER/2008/0070/C, 51 pp.
• Forsyth, G.G., le Maitre, D.C., and van Wilgen, B.W. (2009). Prioritising quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province, CSIR Natural Resources and the Environment Report No. CSIR/NRE/ECO/ER/2009/0094/B

INVASIVE ALIEN PLANT DISSERTATIONS:

• Fatoki, O. B. (2007). Monitoring the re-growth rate of alien vegetation after fire on Agulhas Plain, South Africa. Department of Geography, University of Stellenbosch. MSc thesis: 68 pp.
• Jasson, R. (2005). Management of Acacia species seed banks in the Table Mountain National Park, Cape Peninsula, South Africa. Department of Conservation Ecology, University of Stellenbosch. MSc thesis: 72 pp.
• Vosse, S. (2007). The restoration potential of fynbos riparian seed banks after alien clearing. Department of Conservation Ecology & Entomology, University of Stellenbosch. MSc thesis: 201 pp.
• Law, M. C. (2007). Willingness to pay for the control of water hyacinth in an urban environment of South Africa. Faculty of Commerce. Grahamstown, Rhodes University. MComm thesis: 135 pp.
• Marais, C. (1998). An economic evaluation of invasive alien plant control programmes in the mountain catchment areas of the Western Cape province, South Africa. Faculty of Forestry, University of Stellenbosch. PhD thesis: 189 pp.
• Te Roller, K.S. (2004). Evaluating success of an integrated control programme of Hakea sericea Shrader (Proteaceae) in the Western and Eastern Cape Provinces, South Africa through cartographic analysis. MSc thesis. University of Stellenbosch. 64 pp.
• Ralston, S. (2004). The role of legislation in the management of invasive alien plants: human dimensions affecting the implementation of legal instruments on the Cape Peninsula, South Africa. MSc thesis. Percy Fitzpatrick Institute, University of Cape Town, 50pp.
• Magoba, R.N.N. (2005). Effect of invasion and clearing of alien riparian vegetation on benthic macroinvertebrate and adult Odonata assemblages in Soutpansberg rivers. MSc thesis, University of Stellenbosch, 127 pp.
• Cochran, A.N. (2005). Colour infra-red imagery as a medium for mapping alien vegetation. MSc thesis, Department of Geography & Environmental Management, University of Johannesburg. 52 pp.
• Cobbing, B. L. (2006). The use of Landsat ETM imagery as a suitable data capture source for alien Acacia species for the Working for Water programme. MSc thesis, Department of Geography, Rhodes University, 146 p.
• Wannenburgh, A.M. (2006). a systematic spatial prioritization for invasive alien plant control in South Africa. MSc thesis. Department of Environmental & Geographical Science, University of Cape Town, 107pp.
• Guthrie, G. (2007). Impacts of the invasive reed Arundo donax on biodiversity at the community-ecosystem level. MSc thesis. Biodiversity & Conservation Biology Department, University of the Western Cape, 156pp.
• Krug, R. M. (2008). Modelling Seed Dispersal in Restoration and Invasions. Ph.D. thesis, Stellenbosch University.