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Stem mortality of Acacia nigrescens induced by the synergistic effects of elephants and fire in Kruger National Park, South Africa

Published online by Cambridge University Press:  01 November 2008

Glenn R. Moncrieff ,
Laurence M. Kruger  and
Jeremy J. Midgley
Glenn R. Moncrieff
Affiliation:
Department of Botany, University of Cape Town, Private Bag Rondebosch 7701, South Africa
Laurence M. Kruger
Affiliation:
Department of Botany, University of Cape Town, Private Bag Rondebosch 7701, South Africa Organization for Tropical Studies, Skukuza, South Africa
Jeremy J. Midgley*
Affiliation:
Department of Botany, University of Cape Town, Private Bag Rondebosch 7701, South Africa
*
1Corresponding author. Email: Jeremy.Midgley@uct.ac.za
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Abstract:

One manner in which elephants utilize trees is by removing their bark. This type of utilization is concentrated on the largest trees in the landscape. The role of bark removal in increasing the vulnerability of large trees to fire and the mechanism through which fire damage is mediated were investigated in Kruger National Park, South Africa, by experimentally removing bark and burning Acacia nigrescens stems with diameters ranging between 30 and 68 mm. Also, field surveys were conducted subsequent to natural fires in order to investigate mortality patterns of large trees with dbh greater than 15 cm with bark removed by elephants. An increasing probability of mortality was associated with increasing amounts of bark removal but only if trees were burned. When trees had bark removed but were not burnt, simulating damage only to cambium and phloem, none of the 12 treated stems died in the 4-mo period over which the experiment ran. Moreover, low levels of cambium damage were detected in large burned stems. This suggests that bark removal increases fire-induced xylem damage and that this damage contributes towards stem mortality. In a survey of 437 large trees, bark removal by elephants was frequent on large stems (44%) and larger trees have greater amounts of bark removed. Post-fire mortality of large trees was significantly associated with increasing bark removal and stem diameter. These results indicate that bark removal by elephants increases the vulnerability of stems to fire, resulting in mortality of large stems otherwise protected from fire.

Keywords

Acacia nigrescensbark removalelephant–fire interactionsfireLoxodonta africanasavannastem mortalityxylem
Type
Research Article
Information
Journal of Tropical Ecology , Volume 24 , Issue 6 , November 2008 , pp. 655 - 662
Copyright
Copyright © Cambridge University Press 2008

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References

LITERATURE CITED

BALFOUR, D. A. & MIDGLEY, J. J. 2006. Fire induced stem death in an African acacia is not caused by canopy scorching. Austral Ecology 31:892–896.CrossRefGoogle Scholar
BARNES, R. F. W. 1983. The elephant problem in Ruaha National Park, Tanzania. Biological Conservation 26:127–148.CrossRefGoogle Scholar
BELSKY, A. J. 1994. Influences of trees on savanna productivity: tests of shade, nutrients, and tree-grass competition. Ecology 75:922–932.Google Scholar
BEN-SHAHAR, R. 1993. Patterns of elephant damage in vegetation in northern Botswana. Biological Conservation 65:249–256.Google Scholar
BEUCHNER, H. K. & DAWKINS, H. C. 1961. Vegetation change induced by elephants and fire in Murchison Falls National Park, Uganda. Ecology 42:752–766.CrossRefGoogle Scholar
BOND, W. J. & VAN WILGEN, B.W. 1996. Fire and plants. Chapman & Hall, London. 276 pp.Google Scholar
BOVA, A. S. & DICKINSON, M. B. 2005. Linking surface-fire behaviour, stem heating, and tissue necrosis. Canadian Journal of Forest Research 35:814–822.Google Scholar
DEAN, W. R. J., MILTON, S. J. & JELTSCH, F. 1998. Large trees, fertile islands and birds in arid savanna. Journal of Arid Environments 41:61–78.Google Scholar
DUBLIN, H. T., SINCLAIR, A. R. E. & MCGLADE, J. 1990. Elephants and fire as causes of multiple stable states in the Serengeti-Mara woodlands. Journal of Animal Ecology 59:1147–1164.CrossRefGoogle Scholar
ECKHARDT, H. C., VAN WILGEN, B. W. & BIGGS, H. C. 2000. Trends in woody vegetation cover in the Kruger National Park, South Africa, between 1940 and 1998. African Journal of Ecology 38:108–113.Google Scholar
GADD, M. E. 2002. The impact of elephants on the marula tree Sclerocarya birrea. African Journal of Ecology 40:328–336.Google Scholar
GERTENBACH, W. P. D. 1983. Landscapes of the Kruger National Park. Koedoe 26:9–21.Google Scholar
GIGNOUX, J., CLOBERT, J. & MENAUT, J. C. 1997. Alternative fire resistance strategies in savanna trees. Oecologia 110:576–583.Google Scholar
GILL, A. & ASHTON, D. 1968. The role of bark type in relative tolerance to fire of three central Victorian eucalypts. Australian Journal of Botany 16:491–498.CrossRefGoogle Scholar
GUY, P. R. 1989. The influence of elephants and fire on a Brachystegia–Julbernardia woodland in Zimbabwe. Journal of Tropical Ecology 5:215–226.Google Scholar
HARE, R. C. 1965a. Contribution of bark to fire resistance of southern trees. Journal of Forestry 63:248–251.Google Scholar
HARE, R. C. 1965b. Bark surface and cambium temperatures in simulated forest fires. Journal of Forestry 63:437–440.Google Scholar
HIGGINS, S. I., BOND, W. J. & TROLLOPE, W. S. W. 2000. Fire, resprouting and variability: a recipe for grass-tree coexistence in savanna. Journal of Ecology 88:213–229.Google Scholar
HOFFMANN, W. A & SOLBRIG, O. T. 2003. The role of topkill in the differential response of savanna woody species to fire. Forest Ecology and Management 180:273–286.Google Scholar
HOLDO, R. 2005. Stem mortality following fire in Kalahari sand vegetation: effects of frost, prior damage, and tree neighbourhoods. Plant Ecology 180:77–86.Google Scholar
JONES, J. L., WEBB, B. W., BUTLER, B. W., DICKINSON, M. B., JIMENEZ, D., REARDON, J. & BOVA, A. S. 2006. Prediction and measurement of thermally induced cambial tissue necrosis in tree stems. International Journal of Wildland Fire 15:3–17.Google Scholar
LUDWIG, F., DE KROON, H., BERENDSE, F. & PRINS, H. T. T. 2004. The influence of savanna trees on nutrient, water and light availability and the understorey vegetation. Plant Ecology 170:93–105.Google Scholar
MACGREGOR, S. D. & O'CONNOR, T. G. 2004. Response of Acacia tortilis to utilization by elephants in a semi-arid African savanna. South African Journal of Wildlife Research 34:55–66.Google Scholar
PÉREZ, B. & MORENO, J. M. 1998. Methods for quantifying fire severity in shrubland-fires. Plant Ecology 139:91–101.CrossRefGoogle Scholar
RUNDEL, P. W. 1973. The relationship between basal fire scars and crown damage in giant sequoia. Ecology 54:210–213.CrossRefGoogle Scholar
SHANNON, G., DRUCE, D. J., PAGE, B. R., ECKHARDT, H, C., GRANT, R. & SLOTOW, R. 2008. The utilization of large savanna trees by elephant in southern Kruger National Park. Journal of Tropical Ecology 24:281–289.Google Scholar
TROLLOPE, W. S. W. 1984. Fire in savanna. Pp. 149–175 in Booysen, P. D. V. & Tainton, N. M. (eds.). Ecological effect of fire in South African ecosystems. Springer-Verlag, Berlin.Google Scholar
TYREE, M. T. & SPERRY, J. S. 1988. Vulnerability of xylem to cavitation and embolism. Annual Review of Plant Physiology and Plant Molecular Biology 40:19–36.Google Scholar
UHL, C. & KAUFFMAN, J. B. 1990. Deforestation, fire susceptibility, and potential tree responses to fire in the Eastern Amazon. Ecology 71:437–439.Google Scholar
VINES, R. G. 1968. Heat transfer through bark, and the resistance of trees to fire. Australian Journal of Botany 16:499–514.Google Scholar
YEATON, R. I. 1988. Porcupines, fires and the dynamics of the tree layer of the Burkea africana savanna. Journal of Ecology 76:1017–1029.Google Scholar