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Long-term population changes in the Giant Quiver Tree, Aloe pillansii in the Richtersveld, South Africa

Abstract

With probably fewer than 3000 individuals alive in the biodiversity hotspot of the Succulent Karoo in southern Africa, populations of the endemic, Giant Quiver Tree, Aloe pillansii, are thought to be declining and thus threatened with extinction. Using repeat photography and field data we investigated the long-term changes in one population of A. pillansii at its type locality, the roughly 100 ha Cornell’s Kop in the Richtersveld, South Africa. There are currently 75 individuals alive at this site. Of these, 44% are <1 m in height (seedlings), 4% are 1–3 m (juveniles) and 52% are >3 m (adults). An analysis of 14 repeat photographs shows that since 1937 an average of 1.4% of the plants >3 m in height has died annually. At this rate all the remaining 39 plants on Cornell’s Kop in this size class will be dead in 71 years. The relative paucity of plants in the 1–3 m size classes could be explained by several factors including plant theft, animal damage and unfavourable recruitment conditions during the first 80 years of the 20th century. Annual growth rates decrease as plants age. Individuals <1 m in height grow at 42.5 mm yr−1 while plants 1–3 m and those >3 m grow at 31.0 and 16.4 mm yr−1 respectively. At 8 m, the tallest plant on Cornell’s Kop could be as old as 382 years and thus to maintain itself at this site, A. pillansii would only need to recruit relatively infrequently. The relatively high proportion of seedlings suggests that conditions have recently been favourable for recruitment at this site. Seedling ages, estimated from their heights, indicate that over 50% of the plants <1 m in height germinated 5–10 years ago. This is consistent with local rainfall records which show that rainfall was consistently above the long-term annual average of 75 mm during this period. However, the loss of six seedlings from the population in the last 5 years, probably due to grazing or theft, suggests that without intervention this species will not survive on Cornell’s Kop.

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References

  1. Bayer M.B. (1974). The Karoo Botanic Garden – Worcester. Aloe 12(2):54–57

  2. Bolus C., Hoffman M.T., Todd S.W, Powell E., Hendricks H.H. and Clark B. (2004). The distribution and population structure of Aloe pillansii in South Africa in relation to climate and elevation. Transactions of the Royal Society of South Africa 59(2):133–140

  3. Bowers J.E., Webb R.H. and Rondeau R.J. (1995). Longevity, recruitment and mortality of desert plants in Grand Canyon, Arizona, USA. Journal of Vegetation Science 6:551–564

  4. Cowling R.M. and Hilton-Taylor C. (1994). Patterns of plant diversity and endemisim in southern Africa: an overview. In: Huntley B.J. (eds), Botanical Diversity in Southern Africa. Strelitzia 1 National Botanical Institute, Pretoria, pp 31–52

  5. Cowling R.M. and Pierce S.M. (1999). Namaqualand: A Succulent Desert. Fernwood Press, Cape Town

  6. Drezner T.D. (2004). Saguaro recruitment over their American range: a separation and comparison of summer temperature and rainfall. Journal of Arid Environments 56:509–524

  7. Du Bois K. (1997). Illegal trade in endangered species. African Security Review 6(1):28–41

  8. Escoto-Rodriguez M. and Bullock S.H. (2002). Long-term growth rates of cirio (Fouquieria columnaris), a giant succulent of the Sonoran Desert in Baja California. Journal of Arid Environments 50:593–611

  9. Foden W. 2002. A demographic study of Aloe dichotoma in the Succulent Karoo: Are the effects of climate change already apparent? Unpublished M.SC., thesis, Percy Fitzpatrick Institute of African Ornithology, University of Cape Town

  10. Golding J.S. (eds) (2002). Southern African Plants Red Data Lists. Southern African Botanical Diversity Network Report No. 14. SABONET, Pretoria

  11. Hilton-Taylor C. and Le Roux A. (1989). Conservation status of the Fynbos and Karoo biomes. In: Huntley B.J. (eds), Biotic Diversity in Southern Africa: Concepts and Conservation. Oxford University Press, Cape Town, pp. 202–223

  12. Hughes L. (2000). Biological consequences of global warming: is the signal already apparent? Trends in Ecology and Evolution 15:56–61

  13. Jordan P.W. and Nobel P.S. (1979). Infrequent establishment of seedlings of Agave desertii (Agavaceae) in the northwestern Sonoran Desert. American Journal of Botany 66(9):1079–1084

  14. Jordan P.W. and Nobel P.S. (1981). Seedling establishment of Ferocactus acanthodes in relation to drought. Ecology 62(4):901–906

  15. Jordan P.W. and Nobel P.S. (1982). Height distribution of two species of cacti in relation to rainfall, seedling establishment and growth. Botanical Gazette 143(4):511–517

  16. Kaleme P.K. 2003. Regional differences in the long-term population dynamics of a succulent tree, Aloe dichotoma in the semi-arid Karoo, South Africa as revealed by repeat photography. Unpublished M.SC., thesis, Percy Fitzpatrick Institute of African Ornithology, University of Cape Town

  17. La Val R.K. (2004). Impact of global warming and locally changing climate on tropical cloud forest bats. Journal of Mammalogy 85(2):237–244

  18. Loots S. and Mannheimer C. (2003). The status of Aloe pillansii L. Guthrie (Aloaceae) in Namibia. Bradleya 21:57–62

  19. Marloth R. (1915). The flora of South Africa Vol (IV). Cambridge University Press, Cape Town

  20. Midgley J.J. (1996). Tree succulents in the Richtersveld. Veld & Flora 82(3):74–75

  21. Midgley J.J., Cowling R.M., Hendricks H., Desmet P.G., Esler K., Rundel P. (1997). Population ecology of tree succulents (Aloe and Pachypodium) in the arid western Cape: decline of keystone species. Biodiversity and Conservation 6:869–876

  22. Midgley G.F., Rutherford M.C. and Bond W.J. (2001). The heat is on: Impacts of climate change on plant diversity in South Africa. National Botanical Institute, South Africa

  23. Midgley G.F., Hannah L., Millar D., Rutherford M.C., and Powrie L.W. (2002). Assessing the vulnerability of species richness to anthropogenic climate change in a biodiversity hotspot. Global Ecology and Biogeography 11:445–451

  24. Midgley J.J. (1997). The decline of Aloe pillansii at Cornell’s Kop in the Richtersveld. Aloe 34(1 & 2):39

  25. Myers N., Mittermeier R.A. Mittermeier C.G. da Fonseca G.A.B. and Kent J. (2000). Biodiversity hotspots for conservation priorities. Nature 403:853–858

  26. Myneni R.B. and Keeling C.D. (1997). Increased plant growth in the northern high latitudes from1981 to 1991. Nature 386:698–701

  27. Parmesan C., Ryrholm N., Stefanescu C., Hill J.K., Thomas C.D., Descimon H., Huntley B., Kaila L., Kullberg J., Tammaru T., Tennet W.J., Thomas J.A., and Warren M. (1999). Polewards shifts of geographical ranges of butterfly species associated with global warming. Nature 399:579–583

  28. Pounds J.A., Fogden M.P.L. and Campbell J.H. (1999). Biological response to climate change on a tropical mountain. Nature 398:611–615

  29. Powell E., Clark B., Hendricks H., Pretorius L. and Roderick J. 2000. The population status of Aloe pillansii, Richtersveld, South Africa. Unpublished report by the “Kokerboom Vetplant Klub” for South African National Parks (SANP)

  30. Powell E., Hendricks H., Clark B., Pretorius L., Roderick J. and Garrett D. (2003) The plight of Aloe pillansii. Veld & Flora 79(4):150–151

  31. Reynolds G.W. (1950). The Aloes of South Africa. Cape Town, Balkema

  32. Rogers D. (2004). Pillansii in peril. Africa Geographic 12(5): 24

  33. Smith R.I.L. (1994). Vascular plants as bioindicators of regional warming in Antartica. Oecologia 99:322–328

  34. Sturm M., Racine C. and Tape K. (2001). Climate Change: increasing shrub abundance in the Arctic. Nature 411:546–547

  35. Van Jaarsveld E. (1987). The succulent riches of South Africa and Namibia and their adaptive strategies. Aloe 24(3 & 4):47–92

  36. Vogel J. C. (1974). The lifespan of the Kokerboom. Aloe 12(2):66–68

  37. Williamson G. (1998). The ecological status of Aloe pillansii (Aloaceae) in the Richtersveld with particular reference to Cornell’s Kop. Bradleya 16:1–8

  38. Williamson G. (2000). Richtersveld- the enchanted wilderness. Umdaus Press, Hatfield, South Africa

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Acknowledgements

BIOTA Southern Africa, sponsored by the German Federal Ministry of Education and Research under promotion number 01 LC 0024A, contributed significantly to the success of this project as did the European-Union funded WADE project. The support of the Mazda Wildlife Fund for the use of a courtesy vehicle is appreciated. Thanks to Norbert Juergens, Simon Todd and Leo Thamm for their contributions to this article and to the photographers who supplied the photographs used in the study including Ernst van Jaarsveld, Hans Dieter Ihlenfeldt and the South African National Biodiversity Institute.

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Correspondence to Timm Hoffman.

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Duncan, J., Hoffman, T., Rohde, R. et al. Long-term population changes in the Giant Quiver Tree, Aloe pillansii in the Richtersveld, South Africa. Plant Ecol 185, 73–84 (2006). https://doi.org/10.1007/s11258-005-9085-0

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Keywords

  • Anthropogenic impacts
  • Climate change
  • Population dynamics
  • Repeat photography
  • Succulent Karoo