Abstract
The invasion of natural ecosystems by alien plants is a serious environmental problem that threatens the sustainable use of benefits derived from such ecosytems. Most past studies in this field have focussed on the history, ecology and management of invasive alien species, and little work has been done on the economic aspects and consequences of invasions. This paper reviews what is known of the economic consequences of alien plant invasions in South Africa. These economic arguments have been used to successfully launch the largest environmental management programme in Africa.
Ten million hectares of South Africa has been invaded by 180 alien species, but their impacts are not fully understood, although they are undoubtedly significant. The indications are that the total costs of these impacts are substantial. Selected studies show that invasions have reduced the value of fynbos ecosystems by over US$ 11.75 billion; that the total cost of invasion would be about US$ 3.2 billion on the Agulhas Plain alone; that the net present cost of invasion by black wattles amounts to US$ 1.4 billion; that invasions by red water fern have cost US$ 58 million; and that the cost to clear the alien plant invasions in South Africa is around US$ 1.2 billion. These few examples indicate that the economic consequences of invasions are huge.
One of the unique aspects of invasive plant control programmes in South Africa has been the ability to leverage further benefits (mainly through employment) for the expensive control programmes from the government's poverty relief budget. This has made it possible to allocate substantial funding to a programme that would otherwise have struggled to obtain significant support. Biological control of invasive species also offers considerable benefits, but is often the subject of debate. We believe that, at least in the case of many invasive alien plant species in South Africa, biological control offers one of the best, and most cost-effective, interventions for addressing the problem.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Avis, A.M.: 1989, 'A review of coastal dune stabilization in the Cape Province of South Africa', Landscape and Urban Planning 18, 55–68.
Baars, J-R. andNeser, S.: 1999, 'Past and present initiatives on the biological control of Lantana camara (Verbenaceae) in South Africa', African Entomology Memoir 1, 21–33.
Breytenbach, G.J.: 1986, 'Impacts of alien organisms on terrestrial communities with emphasis on communities of the south-western Cape' in I.A.W. Macdonald,F.J. Kruger andA.A. Ferrar (eds.), The ecology and management of biological invasions in southern Africa, Cape Town, Oxford University Press, pp. 229–238.
Breytenbach, G.J.: 1989, 'Alien control: Can we afford to slash and burn hakea in fynbos ecosystems?', South African Forestry Journal 151, 6–16.
Bromilow, C.: 1995, Problem plants of South Africa. Pretoria, Briza Publications.
Brown, C.J. andGubb, A.A.: 1986, 'Invasive alien organisms in the Namib Desert, Upper Karoo and the arid and semi-arid savannas of western southern Africa' in I.A.W. Macdonald,F.J. Kruger andA.A. Ferrar (eds.), The ecology and management of biological invasions in southern Africa, Cape Town, Oxford University Press, pp. 93–108.
Brutsch, M.O. andZimmermann, H.G.: 1993, 'The prickly pear (Opuntia ficus-indica [Cactaceae]) in South Africa: Utilization of the naturalized weed, and of the cultivated plants', Economic Botany 47, 154–162.
Cellier, S.: 1994, 'Are all trees green? The forest industry replies', Africa Environment and Wildlife 2(1), 79–85.
Chapin, F.S. III,Reynolds, H.L.,D'Antonio, C.M. andEckhart, V.M.: 1996, 'The functional role of species in terrestrial ecosystems', in B. Walker andW. Steffen (eds.), Global change and terrestrial ecosystems, Cambridge University Press, pp. 403–428.
Cilliers, C.J.: 1999, 'Biological control of parrot's feather, Myriophyllum aquaticum (Vell.) Verd. (Haloragaceae), in South Africa', African Entomology Memoir 1, 113–118.
Cole, N.S.,Lombard, A.T.,Cowling, R.M.,Euston-Brown, D.,Richardson, D.M. andHeijnis, C.E.: 2000, Framework for a conservation plan for the Agulhas Plain, Cape Floristic Region, South Africa, Institute for Plant Conservation, University of Cape Town.
Cowling, R.M.,Pressey, R.L.,Lombard, A.T.,Heijnis, C.E.,Richardson, D.M. andCole, N.: 1999, Framework for a conservation plan for the Cape Floristic Region, Institute for Plant Conservation, University of Cape Town.
Cowling, R.M. andHilton-Taylor, C.: 1994, 'Patterns of plant diversity and endemism in southern Africa: an overview', in B.J. Huntley (ed.), Botanical diversity in southern Africa, Pretoria, National Botanical Institute, pp 31–52.
Department ofWater Affairs and Forestry: 1997, TheWorking forWater Programme 1996/97 Annual Report, Department of Water Affairs and Forestry, Pretoria.
De Wit, M., Crookes, D. and van Wilgen, B.W.: 'Conflicts of interest in environmental management: Estimating the costs and benefits of black wattle (Acacia mearnsii) in South Africa', Biological Invasions, (in press).
Dukes, J.S. and Mooney, H.A: 'Biological invaders disrupt ecosystem processes in western North America.', in G.A. Bradshaw, H.A. Mooney and P. Alaback, P. (eds.), Disruptions and variability in ecosystem processes and patterns, New York, Springer-Verlag, (in press).
Dye, P.: 1996, 'Climate, forest and streamflow relationships in South African afforested catchments', Commonwealth Forestry Review 75, 31–38.
Eckert, J.B.,Liebenberg, G.F. andTroskie, D.P.: 1997, The Macroeconomics of Western Cape Agriculture: Analysis With A Social Accounting Matrix, Department of Agriculture of the Western Cape, Cape Town.
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', Working forWater Programme, Department ofWater Affairs and Forestry, Cape Town.
Fraser, M.W.: 1990, 'Foods of Redwinged Starlings and the potential for avian dispersal of Acacia cyclops at the Cape of Good Hope Nature Reserve', South African Journal of Ecology 1, 73–76.
Geldenhuys, C.J.,le Roux, P.J. andCooper, K.H.: 1986, 'Alien invasions in indigenous evergreen forest'. in I.A.W. Macdonald,F.J. Kruger andA.A. Ferrar (eds.), The ecology and management of biological invasions in southern Africa, Cape Town, Oxford University Press, pp. 119–131.
Hall, A.V.: 1987, 'Threatened plants in the fynbos and karoo biomes', Biological Conservation 40, 29–52.
Harding, G.B. andBate, G.C.: 1991, 'The occurrence of invasive Prosopis species in the north-western Cape, South Africa', South African Journal of Science 87, 188–192.
Henderson L.: 1991, 'Alien invasive Salix spp. (willows) in the Grassland Biome of South Africa', South African Forestry Journal 157, 91–95.
Henderson, L.: 1998, 'South African plant invaders atlas (SAPIA)', Applied Plant Sciences 12, 31.
Henderson, L.: 1999, 'The southern African Plant Invaders Atlas (SAPIA) and its contribution to biological weed control', African Entomology Memoir 1, 159–163.
Heydenrych, B.: 1999, 'An investigation of land-use practices on the Agulhas Plain (South Africa), with emphasis on socio-economic and conservation issues', M.Sc. dissertation, University of Cape Town.
Higgins, S.I.,Azorin, E.J.,Cowling, R.M. andMorris, M.J.: 1997a, 'A dynamic ecological-economic model as a tool for conflict resolution in an invasive alien, biological control and native-plant scenario', Ecological Economics 22, 141–154.
Higgins, S.I.,Turpie, J.K.,Costanza, R.,Cowling, R.M.,Le Maitre, D.C.,Marais, C. andMidgley, G.F.: 1997b, 'An ecological economic simulation model of mountain fynbos ecosystems: Dynamics, valuation and management', Ecological Economics 22, 155–169.
Higgins, S.I.,Richardson, D.M.,Cowling, R.M. andTrinder-Smith, T.H.: 1999, 'Predicting the landscapescale distribution of alien plants and their threat to plant diversity', Conservation Biology 13, 303–313.
Hill, M.P. andCilliers, C.J.: 1999, 'A review of the arthropod natural enemies, and factors that influence their efficacy, in the biological control of water hyacinth, Eichhornia crassipes (Mart.) Solms-Laubach (Ponterderiaceae), in South Africa', African Entomology Memoir 1, 103–112.
Hoffmann, J.H. andMoran, C.M.: 1988, 'The invasive weed, Sesbania punicea in South Africa and prospects for its biological control', South African Journal of Science 84, 740–742.
Hoffman, M.T.,Todd, S.,Ntshona, Z. andTurner, S.: 1999, Land degradation in South Africa, National Botanical Institute, Kirstenbosch, South Africa.
Holmes, P.M. andCowling, R.M.: 1997a, 'The effects of invasion by Acacia saligna on the guild structure and regeneration capabilities of South African fynbos shrublands', Journal of Applied Ecology 34, 317–332.
Holmes, P.M. andCowling, R.M.: 1997b, 'Diversity, composition and guild structure relationships between soil-stored seed banks and mature vegetation in alien plant-invaded South African fynbos shrublands', Plant Ecology 133, 107–122.
Hosking, S.G. andDu Preez, M.: 1999, 'A cost-benefit analysis of removing alien trees in the Tsitsikamma mountain catchment', South African Journal of Science 95, 442–448.
Johannesmeier, M.F.: 1985, Beeplants of the South-Western Cape. Department of Agriculture, Pretoria, 59 pp.
Johns, M.: 1993, 'Are all trees green? The spotlight on forestry', Africa Environment andWildlife 1(3), 77–85.
Kaiser, J.: 1999, 'Stemming the tide of invasive species', Science 285, 1836–1841.
Knight, R.S. andMacdonald, I.A.W.: 1991, 'Acacias and korhaans: an artificially assembled seed dispersal system', South African Journal of Botany 57, 220–225.
Kruger, F.J.,Reid, P.,Mayet, M.,Alberts, W.,Goldammer, G.J. andTolhurst, K.: 2000, A review of the veld fires in theWestern Cape during 15 to 25 January 2000, Department ofWater Affairs and Forestry, Pretoria.
Le Maitre, D.C.,Versfeld, D.B. andChapman, R.A.: 2000, 'The impact of invading alien plants on surface water resources in South Africa: A preliminary assessment', Water SA 26, 397–408.
Le Maitre, D.C.,van Wilgen, B.W.,Chapman, R.A. andMcKelly, D.H.: 1996, 'Invasive plants and water resources in the western Cape Province, South Africa: modelling the consequences of a lack of management', Journal of Applied Ecology 33, 161–172.
Le Maitre, D.C., vanWilgen, B.W., Gelderblom, C.M., Bailey, C., Chapman, R.A. and Nel, J.: 'Invasive alien trees and water resources in South Africa: Case studies of the costs and benefits of management', Forest Ecology and Management, (in press).
Low, A.B. andRebelo, A.G.: 1996, Vegetation of South Africa, Lesotho and Swaziland. Department of Environmental Affairs and Tourism, Pretoria.
Macdonald, I.A.W.: 1983, 'Alien trees, shrubs and creepers invading indigenous vegetation in the Hluhluwe-Umfolozi Game Reserve Complex in Natal', Bothalia 14, 949–959.
Macdonald, I.A.W.: 1986, 'Range expansion in the Pied Barbet and the spread of alien tree species in southern Africa', Ostrich 57, 75–94.
Macdonald, I.A.W.,Kruger, F.J. andFerrar, A.A.: 1986, The ecology and management of biological invasions in southern Africa, Cape Town, Oxford University Press.
Marais, C.: 1998, An economic evaluation of invasive alien plant control programmes in the mountain catchment areas of theWestern Cape Province, South Africa, Ph.D. dissertation, University of Stellenbosch.
Milton, S.J.: 1981, 'Litterfall of the exotic Acacias in the South Western Cape', Journal of South African Botany 47, 147–155.
Milton, S.J., andSiefried, W.R.: 1981, 'Above-ground biomass of Australian Acacias in the Southern Cape, South Africa', Journal of South African Botany 47, 701–716.
Milton, S.J.,Zimmermann, H.G. andHoffmann, J.H.: 1999, 'Alien plant invaders of the karoo: attributes, impacts and control, in W.R.J. Dean andS.J. Milton (eds.), The karoo-Ecological patterns and process, Cambridge, Cambridge University Press, pp. 274–287.
Musil, C.F.: 1993, 'Effect of invasive Australian acacias on the regeneration, growth and nutrient chemistry of South African lowland fynbos', Journal of Applied Ecology 30, 361–372.
Musil, C.F. andMidgley, G.F.: 1990, 'The relative impact of invasive Australian acacias, fire and season on the soil chemical status of a sand plain lowland fynbos community', South African Journal of Botany 56, 419–427.
Oatley, T.B.: 1984, 'Exploitation of a new niche by the Rameron Pigeon Columba arquatrix in Natal', Proceedings of the Fifth Pan-African Ornithological Congress, Johannesburg, Southern African Ornithological Society, pp. 323–330.
Olckers, T. andHill, M.P.: 1999, 'Biological control of weeds in South Africa (1990–1998)', African Entomology, Memoir No. 1.
Parker, I.M.,Simberloff, D.,Lonsdale, W.M.,Goodell, K.,Wonham, M.,Kareiva, P.M.,Williamson, M.H.,Von Holle, B.,Moyle, P.B.,Byers, J.E. andGoldwasser, L.: 1999, 'Impact: toward a framework for understanding the ecological effect of invaders', Biological Invasions 1, 3–19.
Pieterse, P.J. andBoucher, C.: 1997, 'A.C.A.C.I.A. (A Case Against Controlling Introduced Acacias)-19 years late r', South African Forestry Journal 180, 37–44.
Prinsloo, F.W. andScott, D.F.: 1999, 'Streamflow responses to the clearing of alien trees from riparian zones at three sites in the Western Cape', South African Forestry Journal 185, 1–7.
Richardson, D.M.: 1998, 'Forestry trees as invasive aliens', Conservation Biology 12, 18–26.
Richardson, D.M. andVanWilgen, B.W.: 1986, 'The effects of fire in felled Hakea sericea and natural fynbos and implications for weed control in mountain catchments', South African Forestry Journal 139, 4–14.
Richardson, D.M.,Macdonald, I.A.W.,Holmes, P.M. andCowling, R.M.: 1992, 'Plant and animal invasions', in R.M. Cowling (ed.), The ecology of fynbos, Cape Town, Oxford University Press, pp. 271–308.
Richardson, D.M.,Macdonald, I.A.W.,Hoffmann, J.H. andHenderson, L.: 1997, 'Alien plant invasions', in R.M Cowling,D.M. Richardson, andS.M. Pierce (eds.), Vegetation of Southern Africa, Cambridge, Cambridge University Press, pp. 534–570.
Richardson, D.M., Cambray, J.A.,Chapman, R.A.,Dean, W.R.J.,Griffiths, C.L.,Le Maitre, D.C.,Newton, D.J. andWinstanley, T.: 'Vectors and pathways of biological invasions in South Africa-Past, future and present', in G. Ruiz andJ. Carlton (eds.), Pathways of invasions: strategies for management across space and time, Washington, D.C., Island Press, (in press).
Samways, M.J.,Caldwell, P.M. andOsborn, R.: 1996, 'Ground-living invertebrate assemblages in native, planted and invasive vegetation in South Africa', Agriculture, Ecosystems and Environment 59, 19–32.
Scott, D.F.: 1999, Report on an inspection of the burn site between Fish Hoek and Glencairn, Monday 10 May, 1999, Ad hoc report prepared for Gibb Africa, Cape Town.
Scott, D.F.,Prinsloo, F.W., andLe Maitre, D.C.: 2000, The role of invasive alien vegetation in the Cape Peninsula fires of January 2000, Report ENV-S-C 2000–039, Division of Water, Environment and Forestry Technology, CSIR, Stellenbosch.
Seydack A.H.W.: 1992, 'Fire management options in fynbos mountain catchment areas', South African Forestry Journal 161, 53–58.
Steenkamp, H.E. andChown, S.L.: 1996, 'Influence of dense stands of an exotic tree, Prosopis glandulosa, Benson, on a savanna dung beetle (Coleoptera: Scarabaeinae) assemblage in southern Africa', Biological Conservation 78, 305–311.
Stirton, C.M.: 1978, 'Plant invaders, beautiful but dangerous', Cape Provincial Administration, Cape Town.
Stirton, C.H.: 1981, 'Notes on the taxonomy of Rubus in southern Africa'. Bothalia 13, 331–332.
Stock, W.D. andAllsopp, N.: 1992, 'Functional perspectives of ecosystems', in R.M. Cowling (ed.), The ecology of fynbos; Nutrients, Fire and Diversity. Cape Town, Oxford University Press, pp. 241–259.
Stubbings, J.A.: 1977, 'Acase against controlling introduced Acacias (A.C.A.C.I.A.)', South African Forestry Journal 102, 8–14.
Turpie, J. andHeydenrych, B.: 2000, 'Economic consequences of alien infestation of the Cape Floral Kingdom's Fynbos vegetation', in C. Perrins,M. Williamson andS. Dalmazzone (eds.), The economics of biological invasions, Cheltenham, Edward Elgar, pp. 152–182.
Van Wilgen, B.W. andRichardson, D.M.: 1985, 'The effects of alien shrub invasions on vegetation structure and fire behaviour in South African fynbos shrublands: A simulation study', Journal of Applied Ecology 22, 955–966.
Van Wilgen, B.W.,Bond, W.J. andRichardson, D.M.: 1992, 'Ecosystem Management' in R.M. Cowling, (ed.), The Ecology of Fynbos; Nutrients, Fire and Diversity. Cape Town, Oxford University Press, pp. 345–371.
Van Wilgen, B.W.,Cowling, R.M. andBurgers, C.J.: 1996, 'Valuation of ecosystem services-A case study from South African fynbos ecosystems', Bioscience 46, 184–189.
Van Wilgen, B.W.,Little, P.R.,Chapman, R.A.,Gorgens, A.H.M.,Willems, T. andMarais, C.: 1997, 'The sustainable development of water resources: History, financial costs, and benefits of alien plant control programmes', South African Journal of Science 93, 404–411.
Van Wilgen, B.W.,Le Maitre, D.C. andCowling, R.M.: 1998, 'Ecosystem services, efficiency, sustainability and equity: South Africa's Working for Water Programme', Trends in Ecology and Evolution 13, 378.
Van Wilgen, B.W. andvan Wyk, E.: 1999, 'Invading alien plants in South Africa: Impacts and solutions', in D. Eldridge andD. Freudenberger (eds.), People and rangelands: Building the future, Proceedings of the VI International Rangeland Congress, Townsville, Australia, pp. 566–571.
Van Wilgen, B.W.,van der Heyden, F.,Zimmermann, H.G.,Magadlela, D. andWillems, T.: 2000, 'Big returns from small organisms: developing a strategy for the biological control of invasive alien plants in South Africa', South African Journal of Science 96, 148–152.
Versfeld, D.B.,Le Maitre, D.C. andChapman, R.A.: 1998, Alien Invading Plants and Water Resources in South Africa: A preliminary assessment, Report TT99/98, Water Research Commission, Pretoria.
Yelenik, S.: 2000, Ecosystem-level feedbacks of N-fixing invasive aliens in lowland fynbos, M.Sc. dissertation, University of Cape Town.
Whiteford, A. andMcgrath, M.: 1994, Distribution Of Income In South Africa, Human Sciences Research Council, Pretoria.
Witkowski, E.T.F.: 1991, 'Effects of invasive alien Acacias on nutrient cycling in the coastal lowlands of the Cape Fynbos', Journal of Applied Ecology 28, 1–15.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
van Wilgen, B., Richardson, D., Le Maitre, D. et al. 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 (2001). https://doi.org/10.1023/A:1011668417953
Issue Date:
DOI: https://doi.org/10.1023/A:1011668417953