Plant Ecology

, Volume 213, Issue 3, pp 483–491

Inter- and intra-plant variations in nitrogen, tannins and shoot growth of Sclerocarya birrea browsed by elephants

  • Peter F. Scogings
  • Robert W. Taylor
  • David Ward


Impacts of elephants (Loxodonta africana africana) on woody vegetation has attracted substantial attention for decades, but plant-level responses remain a gap in the understanding of savanna ecology. Marula (Sclerocarya birrea caffra) forms an important part of elephant diets. We investigated the relationships between browsing intensity and shoot/leaf size, nitrogen (N) and condensed tannin (CT) concentrations in upper and lower canopies of male and female marula individuals in Hluhluwe-iMfolozi Park, South Africa. Browsing intensity (54%) did not differ between sexes, suggesting no preference by elephants for either sex. Females had higher [CT] than males and tannin decreased with increasing browsing intensity in both sexes. In lightly or moderately browsed trees, [CT] was controlled by unmeasured factors such that within-tree impacts of browsing were more variable in lightly/moderately browsed than heavily browsed trees. There was little change in [N] up to ~60% browsing intensity, but [N] increased dramatically at higher intensity. Shoots and leaves on broken branches in the lower canopy were larger (2.5 and 1.2 times, respectively) than those on unbroken branches in either upper or lower canopies. Chemical responses were systemic and potentially influence browsing among trees, while growth responses were strongly localised and potentially influence browsing within trees. Although marula trees are able to compensate vigorously for browsing at the scale of individual organs, trees may become progressively carbon-deficient and have their lives shortened if total plant growth is negatively affected by chronic browsing, e.g. near permanent water.


Browsing lawns Compensatory growth Herbivory Induced responses Plant defence Specific leaf area 


  1. Ågren GI (2008) Stoichiometry and nutrition of plant growth in natural communities. Ann Rev Ecol Evol Syst 39:153–170CrossRefGoogle Scholar
  2. Åhman I (1997) Growth, herbivory and disease in relation to gender in Salix viminalis L. Oecologia 111:61–68CrossRefGoogle Scholar
  3. AOAC (2000) Official methods of analysis, 16th edn. AOAC International, GaithersburgGoogle Scholar
  4. Boundja RP, Midgley JJ (2010) Patterns of elephant impact on woody plants in the Hluhluwe-Imfolozi park, Kwazulu-Natal, South Africa. Afr J Ecol 48:206–214CrossRefGoogle Scholar
  5. Bryant JP, Heitkonig I, Kuropat P, Owen-Smith N (1991) Effects of severe defoliation on the long-term resistance to insect attack and on leaf chemistry in six woody species of the southern African savanna. Am Nat 137:50–63CrossRefGoogle Scholar
  6. Cade BS, Richards JD (2005) User manual for blossom statistical software. USGS, VirginiaGoogle Scholar
  7. Coates Palgrave M (2005) Keith Coates Palgrave trees of southern Africa, 3rd edn. Struik Publishers, Cape TownGoogle Scholar
  8. Codron J, Codron D, Lee-Thorp JA, Sponheimer M, Kirkman K, Duffy KJ, Sealy J (2011) Landscape-scale feeding patterns of African elephant inferred from carbon isotope analysis of feces. Oecologia 165:89–99PubMedCrossRefGoogle Scholar
  9. du Toit JT, Bryant JP, Frisby K (1990) Regrowth and palatability of Acacia shoots following pruning by African savanna browsers. Ecology 71:149–154CrossRefGoogle Scholar
  10. Fornara DA, du Toit JT (2007) Browsing lawns? Responses of Acacia nigrescens to ungulate browsing in an African savanna. Ecology 88:200–209PubMedCrossRefGoogle Scholar
  11. Furstenburg D, van Hoven W (1994) Condensed tannin as anti-defoliate agent against browsing by giraffe (Giraffa camelopardalis) in the Kruger National Park. Comp Biochem Physiol 107A:425–431CrossRefGoogle Scholar
  12. Gadd ME (2002) The impact of elephants on the marula tree Sclerocarya birrea. Afr J Ecol 40:328–336CrossRefGoogle Scholar
  13. Gayler S, Grams TEE, Heller W, Treutter D, Priesack E (2007) A dynamical model of environmental effects on allocation to carbon-based secondary compounds in juvenile trees. Annal Bot 101:1089–1098CrossRefGoogle Scholar
  14. Glynn C, Herms DA, Orians CM, Hansen RC, Larsson S (2007) Testing the growth–differentiation balance hypothesis: dynamic responses of willows to nutrient availability. New Phytol 176:623–634PubMedCrossRefGoogle Scholar
  15. Hagerman AE (2002) Tannin chemistry. Miami University, Oxford, Ohio, USA. Accessed 10 October 2010
  16. Hagerman AE, Butler LG (1989) Choosing appropriate methods and standards for assaying tannin. J Chem Ecol 15:1795–1810CrossRefGoogle Scholar
  17. Helm CV, Witkowski ETF (2008) What don’t we know about Sclerocarya birrea subsp caffra? S Afr J Bot 74:387–388CrossRefGoogle Scholar
  18. Helm CV, Witkowski ETF, Kruger L, Hofmeyr M, Owen-Smith N (2009) Mortality and utilisation of Sclerocarya birrea subsp caffra between 2001 and 2008 in the Kruger National Park, South Africa. S Afr J Bot 75:475–484CrossRefGoogle Scholar
  19. Hemborg AM, Bond WJ (2007) Do browsing elephants damage female trees more? Afr J Ecol 45:41–48CrossRefGoogle Scholar
  20. Herms DA, Mattson WJ (1992) The dilemma of plants: to grow or defend. Q Rev Biol 67:283–335CrossRefGoogle Scholar
  21. Herrera CM (2009) Multiplicity in unity: plant subindividual variation and interactions with animals. University of Chicago Press, ChicagoGoogle Scholar
  22. Hester AJ, Bergman M, Iason GR, Moen J (2006) Impacts of large herbivores on plant community structure and dynamics. In: Danell K, Bergström R, Duncan P, Pastor J (eds) Large herbivore ecology, ecosystem dynamics and conservation. Cambridge University Press, Cambridge, pp 97–141CrossRefGoogle Scholar
  23. Hrabar H, Hattas D, du Toit JT (2009) Differential effects of defoliation by mopane caterpillars and pruning by African elephants on the regrowth of Colophospermum mopane foliage. J Trop Ecol 25:301–309CrossRefGoogle Scholar
  24. Jachmann H, Bell RHV (1985) Utilization by elephants of the Brachystegia woodlands of the Kasungu-National-Park, Malawi. Afr J Ecol 23:245–258CrossRefGoogle Scholar
  25. Jacobs OS, Biggs R (2002a) The impact of the African elephant on marula trees in the Kruger National Park. S Afr J Wildl Res 32:13–22Google Scholar
  26. Jacobs OS, Biggs R (2002b) The status and population structure of the marula in the Kruger National Park. S Afr J Wildl Res 32:1–12Google Scholar
  27. Kerley GIH, Landman M, Kruger L, Owen Smith N (2008) Effects of elephants on ecosystems and biodiversity. In: Scholes RJ, Mennell KG (eds) Elephant management: a scientific assessment for South Africa. Wits University Press, Johannesburg, pp 146–205Google Scholar
  28. Li C, Trombley JD, Schmidt MA, Hagerman AE (2010) Preparation of an acid butanol standard from fresh apples. J Chem Ecol 36:453–460PubMedCrossRefGoogle Scholar
  29. Makhabu SW, Skarpe C, Hytteborn H (2006) Elephant impact on shoot distribution on trees and on rebrowsing by smaller browsers. Acta Oecol 30:136–146CrossRefGoogle Scholar
  30. McNaughton SJ (1984) Grazing lawns: Animals in herds, plant form and coevolution. Am Nat 124:863–886CrossRefGoogle Scholar
  31. Mopipi K, Trollope WSW, Scogings PF (2009) Effects of moisture, nitrogen, grass competition and simulated browsing on the survival and growth of Acacia karroo seedlings. Afr J Ecol 47:680–687CrossRefGoogle Scholar
  32. Mucina L, Rutherford MC (2006) The vegetation of South Africa, Lesotho and Swaziland. South African National Biodiversity Institute, PretoriaGoogle Scholar
  33. Owen-Smith N (2002) Adaptive herbivore ecology. Cambridge University Press, CambridgeCrossRefGoogle Scholar
  34. Page BR (2005) Population structure, demographics and utilization—instructions for data capture. University of KwaZulu-Natal, WestvilleGoogle Scholar
  35. Pooley E (1994) The complete field guide to trees of Natal, Zululand & Transkei. Natal Flora Publications Trust, DurbanGoogle Scholar
  36. Reich PB, Ellsworth DS, Walters MB (1998) Leaf structure (specific leaf area) modulates photosynthesis-nitrogen relations: evidence from within and across species and functional groups. Funct Ecol 12:948–958CrossRefGoogle Scholar
  37. Renton M, Thornby D, Hanan J (2007) Canonical modelling: an approach for intermediate-level simulation of carbon allocation in functional-structural plant models. In: Vos J, Marcelis LFM, de Visser PHB, Struik PC, Evers JB (eds) Functional-structural plant modelling in crop production. Springer, Dordrecht, pp 151–164CrossRefGoogle Scholar
  38. Rooke T, Bergström R (2007) Growth, chemical responses and herbivory after simulated leaf browsing in Combretum apiculatum. Plant Ecol 189:201–212CrossRefGoogle Scholar
  39. Scholes RJ, Bond WJ, Eckhardt HC (2003) Vegetation dynamics in the Kruger ecosystem. In: du Toit JT, Rogers KH, Biggs HC (eds) The Kruger experience. Island Press, Washington, pp 242–262Google Scholar
  40. Scogings PF, Macanda M (2005) Acacia karroo responses to early dormant season defoliation and debarking by goats in a semi-arid subtropical savanna. Plant Ecol 179:193–206CrossRefGoogle Scholar
  41. Scogings PF, Mopipi K (2008) Effects of water, grass and N on responses of Acacia karroo seedlings to early wet season simulated browsing: leaf N, fibre and tannin concentrations. J Arid Env 72:1666–1674CrossRefGoogle Scholar
  42. Scogings PF, Dziba LE, Gordon IJ (2004) Leaf chemistry of woody plants in relation to season, canopy retention and goat browsing in a semi-arid subtropical savanna. Austral Ecol 29:278–286CrossRefGoogle Scholar
  43. Scogings PF, Hjältén J, Skarpe C (2011) Secondary metabolites and nutrients of woody plants in relation to browsing intensity in African savannas. Oecologia. doi:10.1007/s00442-011-2042-9
  44. Shrader AM, Bell C, Bertolli L, Ward D (2011) Forest or the trees: at what level do elephants make foraging decisions? Acta Oecol. doi:10.1016/j.actao.2011.09.009
  45. Skarpe C, Hester AJ (2008) Plant traits, browsing and grazing herbivores, and vegetation dynamics. In: Gordon IJ, Prins HHT (eds) The ecology of browsing and grazing. Springer, Berlin, pp 217–261CrossRefGoogle Scholar
  46. Stuart-Hill GC, Tainton NM (1988) Browse and herbage production in the Eastern Cape thornveld in response to tree size and defoliation frequency. J Grassl Soc S Afr 5:42–47CrossRefGoogle Scholar
  47. SYSTAT Software (2007) SYSTAT 12. SYSTAT Software Inc., San JoseGoogle Scholar
  48. Teague WR (1988) Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves in Acacia karroo Hayne. J Grassl Soc S Afr 5:223–226CrossRefGoogle Scholar
  49. Teague WR (1989) Effect of intensity and frequency of defoliation on aerial growth and carbohydrate reserve levels in Acacia karroo plants. J Grassl Soc S Afr 6:132–138CrossRefGoogle Scholar
  50. van Wyk B, van Oudtshoorn B, Gericke N (1997) Medicinal plants of South Africa. Briza Publications, PretoriaGoogle Scholar
  51. Ward D (2010) The effects of apical meristem damage on growth and defenses of two Acacia species in the Negev desert. Evol Ecol Res 12:589–602Google Scholar
  52. Ward D, Young TP (2002) Effects of large mammalian herbivores and ant symbionts on condensed tannins of Acacia drepanolobium in Kenya. J Chem Ecol 28:913–929Google Scholar
  53. Wessels DCJ, van der Waal C, de Boer WF (2007) Induced chemical defences in Colophospermum mopane trees. Afr J Range Forage Sci 24:141–147CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Peter F. Scogings
    • 1
  • Robert W. Taylor
    • 2
  • David Ward
    • 2
  1. 1.Department of AgricultureUniversity of ZululandKwaDlangezwaSouth Africa
  2. 2.School of Biological and Conservation SciencesUniversity of KwaZulu-NatalScottsvilleSouth Africa

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