The role of Namibian inselbergs in contributing to local and regional plant species richness

Abstract

This study investigated four inselberg landscapes in Namibia's aridNama Karoo. Inselbergs of different size and geology were investigated (a) todetermine environmental variables influencing the number of inselberg restrictedplant species and (b) to investigate seed dispersal spectra as one parameterdescribing functional properties of inselberg specialists. With regard to therole of inselbergs in contributing to local and regional species richness, manyspecies restricted to inselberg habitats occurred (up to 79 species recorded inthis survey) and so contribute to local and regional species richness. As nospecies endemic to an inselberg were recorded in this study, inselbergspecialists may provide an indicator for conservation value of these mountains.Elevation rather than surface area provided a measure for predicting the numberof inselberg specialists. Besides elevation, underlying geology, and resultinglandforms and edaphic conditions, as well as distance to potential mainland alsoinfluenced the number of inselberg specialists. Functional relationships betweeninselbergs based on seed dispersal spectra of inselberg specialists were notconclusive.

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References

  1. Anderson S. 1994. Area and endemism. Quarterly Review of Biology 69: 451–471.

    Google Scholar 

  2. Austin M.P., Cunnigham R.B. and Good R.B. 1983. Altitudinal distribution of several eucalypt species in relation to other environmental factors in southern New SouthWales. Australian Journal of Ecology 8: 169–180.

    Google Scholar 

  3. Barnard P. (ed.) 1998. Biological Diversity in Namibia – A Country Study. Namibian National Biodiversity Task Force, Windhoek, Namibia.

    Google Scholar 

  4. Bazzaz F.A. 1991. Habitat selection in plants. American Naturalist 137: 5116–5130.

    Google Scholar 

  5. Beattie A. and Lyons N. 1975. Seed dispersal in Viola (Violaceae): adaptations and strategies. American Journal of Botany 62: 714–722.

    Google Scholar 

  6. Besler H. 1972. Klimaverhältnisse und klimageomorphologische Zonierung der zentralen Namib (Südwestafrika). Stuttgarter Geographische Studien 83, Stuttgart, Germany.

  7. Biedinger N., Porembski S. and Barthlott W. 2000. Vascular plants on inselbergs: vegetative and reproductive strategies. In: Porembski S. and Barthlott W. (eds), Inselbergs. Springer Verlag, Berlin, pp. 117–142.

    Google Scholar 

  8. Bond W.J. and Richardson D.M. 1990. What can we learn from extinctions and invasions about the effects of climate change? South African Journal of Science 86: 429–433.

    Google Scholar 

  9. Burke A. 1995. Geigeria alata in the Namib desert: seed heteromorphism in an extremely arid environment. Journal of Vegetation Science 6: 473–478.

    Google Scholar 

  10. Burke A. 2002a. Properties of soil pockets on arid Nama Karoo inselbergs – the effect of geology and derived landforms. Journal of Arid Environment 50: 219–234.

    Google Scholar 

  11. Burke A. 2002b. Island–matrix relationships in Nama Karoo inselberg landscapes. Part I: Do inselbergs provide a refuge for matrix species? Plant Ecology 160: 79–90.

    Google Scholar 

  12. Burke A. 2002c. Plant communities of a central Namib desert inselberg landscape. Journal of Vegetation Science 13: 483–492.

    Google Scholar 

  13. Burke A., Jürgens N. and Seely M.K. 1998. Floristic affinities of an inselberg in the southern Namib Desert – relic of the past, centre of endemism or nothing special? Journal of Biogeography 25: 311–317.

    Google Scholar 

  14. Carr M.R. 1997. PRIMER User Manual. Plymouth Routines in Multivariate Ecological Research. Plymouth Marine Laboratory, Plymouth, UK.

    Google Scholar 

  15. Channel R. and Lomolino M.V. 2000. Dynamic biogeography and conservation of endangered species. Nature 403: 84–86.

    Google Scholar 

  16. Cole D.T. 1986. Migrating cranes and Lithops. Excelsa 12: 4–7.

    Google Scholar 

  17. Cowling R.M., Pressey R.L., Lombard A.T., Desmet P.G. and Ellis A.G. 1999. From representation to persistence: requirements for a sustainable system of conservation areas in the species-rich mediterranean climate desert of southern Africa. Diversity and Distribution 5: 51–71.

    Google Scholar 

  18. Craven P. (ed.) 1999. A Checklist of Namibian Plant Species. Southern African Botanical Diversity Network Report No. 7. 204 pp.

  19. Craven P. and Craven D. 2000. The flora and vegetation of the Brandberg Mountain. Cimbebasia 9: 49–67.

    Google Scholar 

  20. Danin A. 1999. Sandstone outcrops – a major refugium of mediterranean flora in the xeric part of Jordan. Israel Journal of Plant Science 47: 179–187.

    Google Scholar 

  21. Dean W.R.J., Milton S.J. and Siegfried R.W. 1990. Dispersal of seeds as nest material by birds in semiarid Karoo shrubland. Ecology 71: 1299–1306.

    Google Scholar 

  22. Ellner S. and Shmida A. 1981. Why are adaptations for long-range seed dispersal rare in desert plants? Oecologia 51: 133–144.

    Google Scholar 

  23. Fowler N.L. 1986. The role of competition in arid and semiarid regions. Annual Review of Ecological Systems 17: 89–110.

    Google Scholar 

  24. Fowler J. and Cohen L. 1992. Practical Statistics for Field Biology. John Wiley & Sons, New York.

    Google Scholar 

  25. Geological Survey 1980. Geological Map of Namibia. Ministry of Mines and Energy, Geological Survey of Namibia, Windhoek, Namibia.

    Google Scholar 

  26. Geological Survey 1997. Geological Map of Namibia, Sheet 2114 – Omaruru. Ministry of Mines and Energy, Geological Survey of Namibia and Geological Survey of Finland, Windhoek, Namibia.

    Google Scholar 

  27. Goldstein P.Z. 1999. Functional ecosystems and biodiversity buzzwords. Conservation Biology 13: 247–255.

    Google Scholar 

  28. Grime P. 1996. Strategic advances in plant ecology. Science Watch 7: 3–4.

    Google Scholar 

  29. Groeger A. 1995. DieVegetation der Granit-Inselberge Sudvenezuelas: Ökologische und biogeographische Untersuchungen, Diplomarbeit, University of Bonn, Bonn, Germany.

    Google Scholar 

  30. Hall A.V. 1987. Gene flow in plant populations. South African National Scientific Programme Report 141: 134–154.

    Google Scholar 

  31. Harper J.L. 1977. Population Biology of Plants. Academic Press, New York.

    Google Scholar 

  32. Hengeveld R. 1989. Dynamics of Biological Invasions. Chapman & Hall, London.

    Google Scholar 

  33. Jürgens N. and Burke A. 2000. The arid scenario: inselbergs in the Namib desert are rich oases in a poor matrix (Namibia & South Africa). In: Porembski S. and Barthlott W. (eds), Inselbergs. Springer Verlag, Berlin, pp. 237–258.

    Google Scholar 

  34. Maggs G.L., Craven P. and Kolberg H.H. 1998. Plant species richness, endemism, and genetic resources in Namibia. Biodiversity and Conservation 7: 435–446.

    Google Scholar 

  35. Margules C.R. and Pressey R.L. 2000. Systematic conservation planning. Nature 405: 243–253. Motro U. 1991. Avoiding inbreeding and sibling competition: the evolution of sexual dimorphism for dispersal. American Naturalist 137: 108–115.

    Google Scholar 

  36. Mueller-Dombois D. and Ellenberg H. 1974. Aims and Methods of Vegetation Ecology. John Wiley & Sons, New York.

    Google Scholar 

  37. Porembski S. 2000.West African inselberg vegetation. In: Poremski S. and Barthlott W. (eds), Inselbergs. Springer Verlag, Berlin, pp. 177–211.

    Google Scholar 

  38. Porembski S. and Barthlott W. (eds) 2000. Inselbergs – Biotic Diversity of Isolated Rock Outcrops in Tropical and Temperate Regions. Ecological Studies 146. Springer Verlag, Berlin.

  39. Porembski S., Barthlott W., Dorrstock S. and Biedinger N. 1994.Vegetation of rock outcrops in Guinea – granite inselbergs, sandstone table mountains and ferricretes. Flora 189: 315–326.

    Google Scholar 

  40. Rust U. 1973. Beiträge zum Problem der Inselberglandschaften aus dem mittleren Südwestafrika. Hamburger Geographische Studien 23, University of Hamburg, Germany.

    Google Scholar 

  41. Rutherford M.C. 1997. Categorization of biomes. In: Cowling R.M., Richardson M. and Pierce S. (eds), The Vegetation of Southern Africa. Cambridge University Press, Cambridge, UK, pp. 91–98.

    Google Scholar 

  42. Seine R. 1996. Vegetation von Inselbergen in Zimbabwe, Ph.D. Thesis, University of Bonn, Bonn, Germany.

    Google Scholar 

  43. Seine R. and Becker U. 2000. East and southeast Africa. In: Porembski S. and Barthlott W. (eds), Inselbergs. Springer Verlag, Berlin, pp. 213–235.

    Google Scholar 

  44. Seine R., Becker U., Porembski S., Follmann G. and Barthlott W. 1998. Vegetation of inselbergs in Zimbabwe. Edinburgh Journal of Botany 55: 267–293.

    Google Scholar 

  45. Selby M.J. 1982. Form and origin of some bornhardts of the Namib Desert. Zeitschrift Für Geomorphologie NF 26: 1–15.

    Google Scholar 

  46. Shmida A. and Wilson M.V. 1985. Biological determinants of species diversity. Journal of Biogeography 12: 1–20.

    Google Scholar 

  47. Shmida A., Evenari M. and Noy-Meir I. 1986. Hot desert ecosystems: an integrated view. In: Evenari M., Noy-Meir I. and Goodall P. (eds), Ecosystems of the World Vol. 12B. Elsevier Publishers, Amsterdam, pp. 379–387.

    Google Scholar 

  48. Simmons R.E., Griffin M., Griffin R.E., Marais E. and Kolberg H. 1998. Endemism in Namibia: patterns, processes and predictions. Biodiversity and Conservation 7: 513–530.

    Google Scholar 

  49. Tilman D., Lehman C.L. and Yin C.J. 1997. Habitat destruction, dispersal and deterministic extinctions in competitive communities. American Naturalist 149: 407–435.

    Google Scholar 

  50. van der Merwe J.H. 1983. National Atlas of South West Africa. National Book Printers, Goodwood, Western Cape.

    Google Scholar 

  51. van der Pijl L. 1969. Principles of Dispersal in Higher Plants. Springer Verlag, Berlin.

    Google Scholar 

  52. van Rheede van Oudtshoorn K. and van Rooyen M. 1999. Dispersal Biology of Desert Plants. Springer-Verlag, Berlin.

    Google Scholar 

  53. White F. 1983. The Vegetation of Africa. UNESCO, Paris.

    Google Scholar 

  54. Williamson M. 1981. Island Populations. Oxford University Press, Oxford, UK.

    Google Scholar 

  55. Willson M.F. 1983. Plant Reproductive Ecology. John Wiley & Sons, New York.

    Google Scholar 

  56. Wyatt R. 1997. Reproductive ecology of granite outcrop plants from the southeastern United States. Journal of Royal Society of Western Australia 80: 123–129.

    Google Scholar 

  57. Zar J.H. 1984. Biostatistical Analysis. 2nd edn. Prentice Hall Inc., Englewood Cliffs, New Jersey.

    Google Scholar 

  58. Zohary M. 1962. Plant Life of Palestine. Ronald Press Comp., New York.

    Google Scholar 

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Burke, A. The role of Namibian inselbergs in contributing to local and regional plant species richness. Biodiversity and Conservation 12, 469–486 (2003). https://doi.org/10.1023/A:1022491723262

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  • Biodiversity
  • Inselbergs
  • Island habitats
  • Nama Karoo
  • Namib desert
  • Seed dispersal