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Biological Invasions

, 12:211 | Cite as

A landscape-scale assessment of the long-term integrated control of an invasive shrub in South Africa

  • Karen J. EslerEmail author
  • Brian W. van Wilgen
  • Kerry S. te Roller
  • Alan R. Wood
  • Johannes H. van der Merwe
Original Paper

Abstract

The control of invasive alien plants often involves the integration two or more approaches, including mechanical clearing, the application of herbicides, burning, and biological control. More than one species of invasive plant can threaten the same area, which necessitates prioritization in the allocation of scarce resources to support the control of different species. This paper describes the integrated control of the invasive shrub Hakea sericea over four decades in South Africa. The species is widespread across an area of approximately 800 × 200 km, and occurs mainly in rugged, inaccessible and fire-prone mountain areas. The species is serotinous, and produces copious amounts of seed that are wind dispersed after fires. We present a brief history of the control measures which included a combination of felling and burning, augmented by biological control. We used data from two surveys, 22 years apart, to assess changes in distribution and density of the species. The assessment suggested that the overall distribution of the species was reduced by 64%, from ~530,000 to ~190,000 ha between 1979 and 2001. The species either decreased in density, or was eliminated from 492,113 ha, while it increased in density, or colonised 107,192 ha. We conclude that initial programs of mechanical clearing were responsible for reducing the density and extent of infestations, and biological control was largely responsible for the failure of the species to re-colonize cleared sites, or to spread to new areas following unplanned wildfires. We propose that a significant portion of the resources used for clearing Hakea in the past can be reallocated to mechanical control efforts against other invasive species (such as alien pines) for which effective biological control options are not available, provided that sufficient resources are allocated to ensure the widespread and effective implementation of all biological control agents to maintain the advances reported on here.

Keywords

Biological control Mechanical control Fire Fynbos Hakea sericea Invasion management Pines 

Notes

Acknowledgments

We thank the South African National Research Foundation (K. J. Esler, GUN 2053516 and through the Centre for Invasion Biology), and the Working for Water Programme for funding, and Dave Richardson and John Hoffman for useful comments on an earlier version of this manuscript, and Tony Rebelo for advice regarding the use of Protea Atlas Data.

References

  1. Bands DP (1977) Prescribed burning in Cape fynbos catchments. In: Mooney HA, Conrad CE (eds) Proceedings of the symposium on the environmental consequences of fire and fuel management in Mediterranean ecosystems. Palo Alto California, August 1977. USDA Forest Service general Technical report WO-3, pp 245–256Google Scholar
  2. Fenn JA (1980) Control of Hakea in the Western Cape. In: Proceedings of the Third National Weeds Conference of South Africa, Balkema, Cape TownGoogle Scholar
  3. Forsyth GG, van Wilgen BW (2007) Analysis of the fire history records from protected areas in the Western Cape. Report CSIR/NRE/ECO/ER/2007/0118/C. CSIR, StellenboschGoogle Scholar
  4. Fugler SR (1979) Some aspects of the autecology of three Hakea species in the Cape Province, South Africa. Dissertation, University of Cape TownGoogle Scholar
  5. Fugler SR (1983) The control of silky hakea in South Africa. Bothalia 14:977–980Google Scholar
  6. Gordon AJ (1993) The impact of the Hakea seed-moth Carposina autologa (Carposinidae) on the canopy-stored seeds of the weed Hakea sericea (Proteaceae). Agric Ecosyst Environ 45:103–113. doi: 10.1016/0167-8809(93)90062-T Google Scholar
  7. Gordon AJ (1999) A review of established and new insect agents for the biological control of Hakea sericea Schrader (Proteaceae). South Africa. Afr Entomol mem 1:35–43Google Scholar
  8. Gordon AJ (2003) Biology and host range of the stem-boring beetle Aphanasium australe, a promising agent for the biological control of Hakea sericea in South Africa. BioControl 49:341–355Google Scholar
  9. Grand J, Cummings MP, Rebelo TG et al (2007) Biased data reduce efficiency and effectiveness of conservation reserve networks. Ecol Lett 10:364–374. doi: 10.1111/j.1461-0248.2007.01025.x CrossRefPubMedGoogle Scholar
  10. Holmes PM, Richardson DM, van Wilgen BW et al (2000) The recovery of South African fynbos vegetation following alien tree clearing and fire: implications for restoration. Austral Ecol 25:631–639. doi: 10.1046/j.1442-9993.2000.01063.x Google Scholar
  11. Kluge RL, Gordon AJ (2004) The fixed plot survey method for determining the host range of the flowerbud-feeding weevil Dicomada rufa, a candidate for the biological control of Hakea sericea in South Africa. BioControl 48:113–122Google Scholar
  12. Kluge RL, Neser S (1991) Biological control of Hakea sericea (Proteaceae) in South Africa. Agric Ecosyst Environ 37:91–113. doi: 10.1016/0167-8809(91)90141-J CrossRefGoogle Scholar
  13. Kluge RL, Richardson DM (1983) Progress in the fight against hakea. Veld & Flora 69:136–138Google Scholar
  14. Le Maitre DC, van Wilgen BW, Chapman RA et al (1996) Invasive plants and water resources in the Western Cape Province, South Africa: modelling the consequences of a lack of management. J Appl Ecol 33:161–172CrossRefGoogle Scholar
  15. Le Maitre DC, Krug RM, Hoffman JH et al (2008) Hakea sericea: development of a model of the impacts of biological control on population dynamics and rates of spread of an invasive species. Ecol Model 212:342–358CrossRefGoogle Scholar
  16. Lubbe CM, Denman S, Cannon PF et al (2004) Characterization of Colletotrichum species associated with diseases of Proteaceae. Mycologia 96:1268–1279CrossRefGoogle Scholar
  17. Macdonald IAW, Richardson DM (1986) Alien species in the terrestrial ecosystems of the fynbos. In: Macdonald IAW, Kruger FJ et al (eds) The ecology and management of biological invasions in Southern Africa. Oxford University Press, Cape Town, pp 77–91Google Scholar
  18. Marais C, van Wilgen BW, Stevens D (2004) The clearing of invasive alien plants in South Africa: a preliminary assessment of costs and progress. S Afr J Sci 100:97–103Google Scholar
  19. Moody ME, Mack RN (1988) Controlling the spread of plant invasions: the importance of nascent foci. J Appl Ecol 25:1009–1021CrossRefGoogle Scholar
  20. Mooney HA, Mack RN, Mcneely JA et al (2005) Invasive alien species: a new synthesis. Island Press, WashingtonGoogle Scholar
  21. Moran VC, Hoffmann J, Donnelly D et al (2000) Biological control of alien invasive pine trees (Pinus species) in South Africa. In: Spencer NR (ed) Proceedings of the Xth International Symposium on Biological Control of Weeds, CSIRO Entomology, Canberra, Australia, pp 941–953Google Scholar
  22. Moran VC, Hoffmann JH, Olkers T (2004) Politics and ecology in the management of alien woody invasive woody trees: the pivotal role of biocontrol agents that diminish seed production. In: Cullen JM et al (eds) Proceedings of the XI International Symposium on Biological Control of Weeds, CSIRO Entomology, Canberra, Australia, pp 434–439Google Scholar
  23. Morris MJ (1983) Evaluation of field trials with Colletotrichum gloeosporioides for the biological control of Hakea sericea. Phytophylactica 15:13–16Google Scholar
  24. Morris MJ (1989) A method for controlling Hakea sericea Schrad. seedlings using the fungus Colletotrichum gloeosporioides (Penz.) Sacc. Weed Res 29:449–454CrossRefGoogle Scholar
  25. Neser S, Fugler SR (1983) Silky hakea. In: Stirton CH (ed) Plant invaders: beautiful but dangerous. Department of Nature and Environment Conservation of the Cape Provincial Administration, Cape Town, pp 76–79Google Scholar
  26. Richardson DM, Brown PJ (1986) Invasion of mesic mountain fynbos by Pinus radiata. S Afr J Bot 52:529–536Google Scholar
  27. Richardson DM, Manders PT (1985) Predicting pathogen-induced mortality in Hakea sericea (Proteaceae), an aggressive alien plant invader in South Africa. Ann Appl Biol 106:243–254CrossRefGoogle Scholar
  28. Richardson DM, van Wilgen BW, Mitchell DT (1987) Aspects of the reproductive ecology of four Australian Hakea species (Proteaceae) in South Africa. Oecologia 71:1432–1939CrossRefGoogle Scholar
  29. Stirton CH (1978) Plant invaders: beautiful, but dangerous. Department of Nature Conservation of the Cape, Cape Town, p 175Google Scholar
  30. van Wilgen BW, Kruger FJ (1981) Observations on the effects of fire in mountain fynbos at Zachariashoek, Paarl. S Afr J Bot 47:195–212Google Scholar
  31. van Wilgen BW, Richardson DM (1985) The effects of alien shrub invasions on vegetation structure and fire behaviour in South African fynbos shrublands: a simulation study. J Appl Ecol 22:955–966CrossRefGoogle Scholar
  32. van Wilgen BW, Everson CS, Trollope WSW (1990) Fire management in southern Africa: some examples of current objectives, practices and problems. In: Goldammer JG (ed) Fire in the tropical biota: ecosystem processes and global challenges. Springer, Berlin, pp 179–209Google Scholar
  33. van Wilgen BW, Little PR, Chapman RA et al (1997) The sustainable development of water resources: history, financial costs and benefits of alien plant control programmes. S Afr J Sci 93:404–411Google Scholar
  34. van Wilgen BW, Le Maitre DC, Cowling RM et al (1998) Ecosystem services, efficiency, sustainability and equity: South Africa’s working for water programme. Trends Ecol Evol 13:378CrossRefGoogle Scholar
  35. van Wilgen BW, Marais C, Magadlela D (2002) Win-win-win: South Africa’s Working for Water programme. In: Pierce SM et al (eds) Mainstreaming biodiversity in development: case studies from South Africa. Washington DC, The World Bank, pp 5–20Google Scholar
  36. Versfeld DB, van Wilgen BW (1986) Impact of woody aliens on ecosystem properties. In: Kruger FJ et al (eds) The ecology and management of biological invasions in Southern Africa. Oxford University Press, Cape Town, pp 239–257Google Scholar
  37. Wicht CL (1945) Preservation of the vegetation of the south-western Cape. Special publication of the Royal Society of South Africa, Cape TownGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Karen J. Esler
    • 1
    Email author
  • Brian W. van Wilgen
    • 2
  • Kerry S. te Roller
    • 1
  • Alan R. Wood
    • 3
  • Johannes H. van der Merwe
    • 4
  1. 1.Centre for Invasion Biology, Department of Conservation Ecology and EntomologyUniversity of StellenboschMatielandSouth Africa
  2. 2.Centre for Invasion BiologyCSIR Natural Resources and the EnvironmentStellenboschSouth Africa
  3. 3.ARC-Plant Protection Research InstituteStellenboschSouth Africa
  4. 4.Department of Geology, Geography and Environmental StudiesUniversity of StellenboschMatielandSouth Africa

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