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Population dynamics of Hyperiodrilus africanus (Oligochaeta, Eudrilidae) in Ivory Coast

Published online by Cambridge University Press:  25 July 2005

Jérôme Ebagnerin Tondoh
Affiliation:
UFR des Sciences de la Nature/Centre de Recherche en Ecologie, Université d'Abobo-Adjamé, 23 BP 4727 Abidjan 23, Côte d'Ivoire
Patrick Lavelle
Affiliation:
Laboratoire d'Ecologie des Sols Tropicaux, IRD/Université Paris 6, 32, avenue Henri Varagnat, 93143 Bondy Cedex, France

Abstract

The population dynamics of the exotic earthworm Hyperiodrilus africanus was investigated in a secondary forest of the Natural Reserve of Lamto (Ivory Coast) over a period of 19 mo. The objectives were to assess seasonal abundance patterns and to determine the adaptive strategies of this species. Each month, 10 soil samples of 100×100×40 cm and 20 monolith samples of 25×25×30 cm were randomly excavated in a plot of 50×95 m and earthworms were extracted by both hand-sorting and wash-sieving methods. The results show significant inter-annual and seasonal fluctuations in population size. Three factors are likely to control population dynamics: (1) rainfall, (2) soil water content and (3) seasonality. The dry season appears to be the most important environmental factor that regulates population abundance when predation, density-dependent regulation and competition phenomena are ignored. Hyperiodrilus africanus exhibited an r strategy, suggesting a high ability to recover populations affected by drought.

Type
Research Article
Copyright
2005 Cambridge University Press

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