Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-24T00:10:09.590Z Has data issue: false hasContentIssue false
  • English
  • Français

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
Get access Rights & Permissions [Opens in a new window]

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

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

Aarssen, L. W. 1983. Ecological combining ability and competitive combining ability in plants: towards a general evolutionary theory of coexistence in systems of competition. American Naturalist 122:707–731.CrossRefGoogle Scholar
Aarssen, L. W. 1985. Interpretation of the evolutionary consequences of competition in plants: an experimental approach. Oikos 45:99–100.CrossRefGoogle Scholar
Connolly, J. 1986. On difficulties with replacement series methodology in mixture experiments. Journal of Applied Ecology 23:125–137.CrossRefGoogle Scholar
Coughenour, M. B., McNaughton, S. J. & Wallace, L. L. 1985a. Responses of an African tall grass (Hyparrenia filipendula Stapf.) to defoliation and limitations of water and nitrogen. Oecologia 68:80–86.Google Scholar
Coughenour, M. B., McNaughton, S. J. & Wallace, L. L. 1985b. Responses of an African graminoid (Themeda triandra Forsk.) to frequent defoliation, ntirogen and water. Oecologia 68:105–110.CrossRefGoogle Scholar
Frost, P., Medina, E., Solbrig, O. T., Swift, M. & Walker, B. H. 1986. Responses of savanna to stress and disturbance. Biology International, Special Issue 10. International Union of Biological Sciences, Paris. 82 pp.Google Scholar
Goldberg, D. E. 1990. Components of resource competition in plant communities. Pp. 27–49 in Grace, J. B. & Tilman, D. (eds). Perspectives on plant competition. Academic Press, San Diego, California.Google Scholar
Keddy, P. A. 1989. Competition. Chapman & Hall, London.CrossRefGoogle Scholar
McNaughton, S. J. 1985. Ecology of a grazing system: the Serengeti. Ecological Monograph 55:259–294.Google Scholar
McNaughton, S. J. 1992. Laboratory-simulated grazing: interactive effects of defoliation and canopy closure on Serengeti grasses. Ecology 73:170–182.CrossRefGoogle Scholar
Pacala, S. W. & Silander, J. A. 1987. Neighborhood interference among velvet leaf, Abutilon theophrasti and pigweed, Amaranthus retroflexus. Oikos 48:217–224.CrossRefGoogle Scholar
Raventós, J. & Silva, J. F. 1988. Architecture, seasonal growth and interference in three grass species with different flowering phenologies in a tropical savanna. Vegetatio 75:115–123.CrossRefGoogle Scholar
Ray, A. A. (ed.). 1982. SAS user's guide: statistics. SAS Institute Inc., Cary, NC.Google Scholar
Sarmiento, G. 1983a. The savannas of tropical America. Pp. 245–288 in Bourlière, F. (ed.). Tropical savannas. Elsevier, Amsterdam.Google Scholar
Sarmiento, G. 1983b. Patterns of specific and phenological diversity in the grass community of the Venezuelan tropical savannas. Journal of Biogeography. 10:373–391.Google Scholar
Silander, J. A. & Pacala, S. W. 1985. Neighborhood predictors of plant performance. Oecologia 66:256–263.CrossRefGoogle ScholarPubMed
Silva, J. F. 1987. Responses of savannas to stress and disturbances: species dynamics. Pp. 141–156 in Walker, B. H. (ed.). Determinants of tropical savannas. International Union of Biological Sciences, Monograph Series No. 3, Paris.Google Scholar
Silva, J. F. & Ataroff, M. 1985. Phenology, seed crop and germination of coexisting grass species from a tropical savanna in western Venezuela. Acta Oecologica, Oecologia Plantamm 6:41–51.Google Scholar
Silva, J. F. & Castro, F. 1989. Fire, growth and survivorship in a neotropical savanna grass (Andropogon semiberbis (Ness) Kunth) in Venezuela. Journal of Tropical Ecology 5:387–400.CrossRefGoogle Scholar
Silva, J. F., Monasterio, M. & Sarmiento, G. 1971. Reconocimiento ecológico de los Llanos Occidentales. II. El Norte del Estado Barinas. Acta Cientiífica Venezolana 22:61–72.Google Scholar
Silva, J. F., Raventós, J. & Caswell, H. 1990. Fire, fire exclusion and seasonal effects on the growth and survival of two savanna grasses. Acta Oecologica 11:783–800.Google Scholar
Silva, J. F., Raventós, J., Caswell, H. & Trevisan, M. C. 1991. Population responses to fire in a tropical savanna grass: a matrix model approach. Journal of Ecology 79:345–356.CrossRefGoogle Scholar
Silva, J. F. & Sarmiento, G. 1976. La compositión de las sabanas de Barinas en relatión con las unidades edáficas. Acta Científica Venezolana 27:68–78.Google Scholar
Weiner, J. 1982. A neighborhood model of annual-plant interference. Ecology 63:1237–1241.CrossRefGoogle Scholar
Weiner, J. 1984. Neighbourhood interference amongst Pinus rigida individuals. Journal of Ecology 72:183–195.Google Scholar