Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-27T18:15:47.411Z Has data issue: false hasContentIssue false

The fate of mature African Acacia pods and seeds during their passage from the tree to the soil

Published online by Cambridge University Press:  10 July 2009

Maxine F. Miller
Affiliation:
NERC Centre for Population Biology, Imperial College, Silwood Park, Ascot, Berkshire SL5 7PY, UK and Mammal Research Institute, Zoology Department, Pretoria University, Pretoria, 0001, S. Africa

Abstract

The fate of mature Acacia tortilis pods on the tree and ground and A. nilotica pods on the ground were investigated at a site in South Africa. Pods on Acacia trees were browsed only by giraffe whereas pods on the ground were browsed by kudu, impala, steenbok and duiker. In the absence of giraffe most A. tortilis pods fell from the tree to the ground. When giraffe were present they consumed most A. tortilis pods at tree level. Bruchids infested 21.6–54.0% of seeds within pods on the tree. Once fallen, in the absence of browsing ungulates, A. tortilis and A. nilotica pod and seed disappearance could be attributed to burial by termites and ants, seed consumption by rodents and to decomposition; when browsing ungulates were present they consumed most pods on the ground. Between 20.0–47.6% of A. tortilis and 31.0–58.0% of A. nilotica seeds on the ground were infested by bruchids. Ungulate browsing had no effect on bruchid infestation of seeds. This study exemplifies the importance of browsing ungulates as consumers of Acacia pods. Although survival of A. tortilis and A. nilotica seeds was greatest in the absence of browsing ungulates the survival of seeds following pod consumption by ungulates is unknown.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

LITERATURE CITED

Aitkin, M., Anderson, D., Francis, B. & Hinde, J. 1990. Statistical modelling in GLIM. Clarendon Press, Oxford.Google Scholar
Caughley, G. 1976. Analysis of vertebrate populations. John Wiley & Sons.Google Scholar
Coe, M. & Coe, C. 1987. Large herbivores, acacia trees and bruchid beetles. South African Journal of Science 83:624635.Google Scholar
Crawley, M. 1989. The dynamics of animal-plant interactions. Blackwell Scientific Publications, Oxford.Google Scholar
David, J. H. M. 1980. Demography and population dynamics of the striped field mouse, Rhapdomys pumilo, in alien Acacia vegetation on the Cape Flats, Cape Peninsula, South Africa. PhD thesis, Zoology Department, University of Cape Town.Google Scholar
Douglas-Hamilton, I. 1972. On the ecology and behaviour of the African elephant – The elephants of Lake Manyara. DPhil. University of Oxford.Google Scholar
Ernst, W. H. O. 1992. Nutritional aspects in the development of Bruchidius sahlbergi (Coleoptera Bruchidae) in seeds of Acacia erioloba. Journal of Insect Physiology 38:831838.Google Scholar
Ernst, W. H. O., Tolsma, D. J. & Decelle, J. E. 1989. Predation of seeds of Acacia tortilis by insects. Oikos 54:294300.CrossRefGoogle Scholar
Ernst, W. H. O., Decelle, J. E. & Tolsma, D. J. 1990a. Predispersal seed predation in native leguminous shrubs and trees in savannas of Southern Botswana. African Journal of Ecology 28:4554.CrossRefGoogle Scholar
Ernst, W. H. O., Decelle, J. E., Tolsma, D. J. & Verweij, R. A. 1990b. Lifecycle of the bruchid beetle, Bruchidius uberatus and its predation of Acacia nilotica seeds in a tree savanna in Botswana. Entomological Experimental Applications 57:177190.Google Scholar
Fleming, T. H. 1975. Small mammals, their productivity and population dynamics. Pp. 269299 in Golley, F. B., Petrusewicz, K. & Ryszowski, L. (eds). Small mammals, their productivity and population dynamics. Cambridge University Press.Google Scholar
Green, D. S. 1983. The efficacy of dispersal in relation to safe site density. Oecologia 56:270280.CrossRefGoogle ScholarPubMed
Gwynne, M. D. 1969. The nutritive values of Acacia pods in relation to Acacia seed distribution by ungulates. East African Wildlife Journal 7:176178.Google Scholar
Halevy, G. 1974. Effects of gazelle and seed beetles (Bruchidae) on germination and establishment of Acacia species. Israel Journal of Botany 23:120126.Google Scholar
Harper, J. L., Clatworthy, J. N., McNaughton, I. H. & Sager, G. R. 1961. The evolution and ecology of closely related speciess living in the same area. Evolution 15:209227.CrossRefGoogle Scholar
Hoffmann, M. T., Cowling, R. M., Douie, C. & Pierce, S. M. 1989. Seed predation and germination of Acacia erioloba in the Kuiseb River Valley, Namib Desert. South African Journal of Botany 55:103106.CrossRefGoogle Scholar
Holmes, P. M. 1989. Decay rates in buried alien Acacia seed populations of different density. South African Journal of Botany 55:299303.CrossRefGoogle Scholar
Holmes, P. M. 1990. Dispersal and predation in alien Acacia. Oecologia 83:288290.CrossRefGoogle ScholarPubMed
Hulme, P. E. 1990. Small mammal herbivory and plant herbivory in grassland. DPhil. Imperial College at Silwood Park, London University.Google Scholar
Jarman, P. J. 1976. Damage to Acacia tortilis seeds eaten by impala. East African Wildlife Journal 14:223225.CrossRefGoogle Scholar
Kerley, G. H. I. & Erasmus, T. 1991. What do mice select for in seeds? Oecologia 86:261267.Google Scholar
Lamprey, H. F. 1967. Notes on the dispersal and germination of some tree seeds through the agency of mammals and birds. East African Wildlife Journal 5:179180.CrossRefGoogle Scholar
Lamprey, H. F., Halevy, G. & Makacha, S. 1974. Interactions between Acacia, Bruchid beetles and large herbivores. East African Wildlife Journal 12:8185.Google Scholar
McNaughton, S. J. & Georgiadis, N. J. 1986. Ecology of African grazing and browsing mammals. Annual Review of Ecology and Systemalics 1:3965.CrossRefGoogle Scholar
Miller, M. F. & Coe, M. 1993. Is it advantageous for Acacia seeds to be eaten by ungulates? Oikos 66:364368.CrossRefGoogle Scholar
Mwalyosi, R. B. B. 1990. The dynamic ecology of Acacia tortilis woodland in Lake Manyara National Park, Tanzania. African Journal of Ecology 28:189199.Google Scholar
Pellew, R. A. P. 1983. The giraffe and its food source in the Serengeti. II Composition, biomass and production of available browse. African Journal of Ecology 21:241267.CrossRefGoogle Scholar
Pellew, R. A. P. & Southgate, B. J. 1984. The parasitism of Acacia tortilis in the Serengeti. African Journal of Ecology 22:7375.Google Scholar
Smith, T. M. & Shackleton, S. E. 1987. The effects sof shading on the establishment and growth of Acacia tortilis seedlings. South African Journal of Botany 54:375379.Google Scholar
Southgate, B. J. 1981. Univoltine and multivoltine cycles: their significance. Pp. 1722 in Labeyrie, V. (ed.). The ecology of bruchids attacking legumes (pulses). W. Junk, The Hague.Google Scholar
Tolsma, D. J. 1989. On the ecology of savanna ecosystems in southern-eastern Botswana. DPhil Thesis. University of Amsterdam.Google Scholar
Van Tonder, S. J. 1985. Annotated records of South African Bruchidae (Coleoptera) associated with acacias, with a description of a new species. Phytophylactactica 17:143148.Google Scholar
Vesey-Fitzgerald, D. F. 1973. Animal impact on vegetation and plant succession in Lake Manyara National Park, Tanzania. Oikos 24:314325.Google Scholar
Vesey-Fitzgerald, D. F. 1974. The changing state of Acacia xanthophloea groves in Arusha National Park, Tanzania. Biological Conservation 6:4048.CrossRefGoogle Scholar