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Competition effects and responses to variable numbers of neighbours in two tropical savanna grasses in Venezuela

Published online by Cambridge University Press:  10 July 2009

José Raventós  and
Juan F. Silva
José Raventós
Affiliation:
Postgrado de Ecología Tropical, Centro de Investigations Ecológicas de los Andes Tropicales (CIELAT), Facultad de Ciencias, Universidad de los Andes, Mérida, Venezuela
Juan F. Silva
Affiliation:
Postgrado de Ecología Tropical, Centro de Investigations Ecológicas de los Andes Tropicales (CIELAT), Facultad de Ciencias, Universidad de los Andes, Mérida, Venezuela
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Abstract

In a garden experiment we monitored tillering and flowering for target plants of two grass species, surrounded by one to five neighbours and compared them with control plants growing alone. We analysed the results using a non-linear regression. The species differed markedly in their seasonal patterns of growth but these differences faded when growing with two or more neighbours. The presence of neighbours had a significant depressing effect on both tillering and flowering in both species. Effects and responses were strongly asymmetrical concerning species and mode of growth. Andropogon semiberbis is in disadvantage against Trachypogon plumosus concerning vegetative growth. However, T. plumosus is strongly affected in its reproductive growth by competition not only from A. semiberbis but also from conspecific neighbours. We conclude that the complexity of interactions between effects and responses as well as vegetative and reproductive growth could have a net result of competitive equivalence or compensating competitive abilities of these two species.

Keywords

Andropogon semiberbiscoexistencecompetitive abilitygrowthneighbourhoodphenologypopulationreproductionTrachypogon plumosus
Type
Research Article
Information
Journal of Tropical Ecology , Volume 11 , Issue 1 , February 1995 , pp. 39 - 52
Copyright
Copyright © Cambridge University Press 1995

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