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Balanites wilsoniana: elephant dependent dispersal?

Published online by Cambridge University Press:  10 July 2009

Lauren J. Chapman
Affiliation:
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, 02138USA
Colin A. Chapman
Affiliation:
Department of Anthropology, Peabody Museum, Harvard University, Cambridge, Massachusetts, 02138USA
Richard W. Wrangham
Affiliation:
Department of Anthropology, Peabody Museum, Harvard University, Cambridge, Massachusetts, 02138USA

Abstract

This study demonstrates that forest elephants (Loxodonta africana) play a key role as seed dispersal agents for the upper canopy forest tree, Balanites wilsoniana. Seed that passed through elephants had a much greater probability of germinating (50.7%) than seeds from fruits eollected directly from the tree (3%). Of 515 seeds that were collected from under parent trees, 89.1% were rotten at the time of collection, 2.6% had been eaten by forest pigs, 2.8% had been killed by squirrels, and 0.7% had been killed by insect damage. The remaining 4.8% of the seeds were still alive. In 150 hours of focal observations on B. wilsoniana trees, two fruits were seen to be destroyed by squirrels, no fruits were seen to be consumed by potential dispersers, and no evidence of scatter hoarding was found. Experimental seedling stations placed out under parent trees and away from parent trees indicated no significant effect of dispersal on seedling survival. Although elephants are not essential for the successful germination of B. wilsoniana seeds, they do greatly increase probability of germination and play a vital role in their dispersal, suggesting that this is a highly interdependent plant-animal seed dispersal system.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1992

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