Hostname: page-component-586b7cd67f-2plfb Total loading time: 0 Render date: 2024-11-22T16:33:27.100Z Has data issue: false hasContentIssue false
  • English
  • Français

Leaf-cutting ants and forest groves in a tropical parkland savanna of Venezuela: facilitated succession?

Published online by Cambridge University Press:  10 July 2009

Alejandro G. Farji Brener  and
Juan F. Silva
Alejandro G. Farji Brener*
Affiliation:
Postgrado en Ecologia Tropical, Centra de Investigaciones Ecológicas de los Andes Tropicales, Fac. Ciencias, Universidad de los Andes, Mérida 5101, Venezuela
Juan F. Silva
Affiliation:
Postgrado en Ecologia Tropical, Centra de Investigaciones Ecológicas de los Andes Tropicales, Fac. Ciencias, Universidad de los Andes, Mérida 5101, Venezuela
*
1Laboratorio ECOTONO, Depto. de Ecologia, C.C. 1336, Universidad del Comahue, (8400) Bariloche, Argentina.
Get access Rights & Permissions [Opens in a new window]

Abstract

Some savanna areas in the Orinoco Llanos region in Venezuela are characterized by the abundance of small forest groves, resulting in a parkland landscape. We hypothesized that forest groves are the result of colonization of the open savanna by forest species, facilitated by the activity of leaf-cutting ants. In this paper we present results from a field study conducted on an ecotonal belt between a deciduous gallery forest and an open savanna in the western Llanos of Venezuela. In seven transects, trees, groves and leaf-cutting ant nests were counted, size parameters evaluated and distance from grove to forest measured. Soil chemical analysis and microclimatic measurements were performed in the forest, grassland and groves. Floristic composition of the woodland component of the savanna (scattered trees) was very dissimilar from that of the forest, but the composition of the groves was essentially a mixture of both woodland and forest species. Woodland trees were present in all groves, whereas forest trees were present only in larger groves. The size structures of populations of the two types of trees differed significandy according to the size of the grove; also, woodland tree population structure differed significantly between open savanna and groves. The frequency of groves with Atta laevigata nests increased with the size of the grove, and groves with forest trees were positively associated with the presence of nests. A. laevigata nests improved the soil of groves, increasing N, Mg, Ca and organic carbon, but other soil properties were not modified. Temperatures at ground level in the dry season were ameliorated in the groves compared with the grassland, and this effect increased with the size of the grove. We concluded that a dynamic process of grove formation is facilitated by the aggregation of a few woodland trees, followed by the successful invasion of forest trees and a leaf-cutting ant nest. The results did not show any clear sequence of arrival of the ants or the forest trees, but it seems clear that these two would act synergistically, improving conditions for each other.

Keywords

Atta laevigatagrove dynamicsinvasionsleaf-cutter nestplant successionwoodland savanna
Type
Research Article
Information
Journal of Tropical Ecology , Volume 11 , Issue 4 , November 1995 , pp. 651 - 669
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

Alvarado, A., Berish, C. W. & Peralta, F. 1981. Leaf-cutter ant (Atta cephalotes) influence on the morphology of andepts in Costa Rica. Soil Science Society of America Journal 45:790–794.CrossRefGoogle Scholar
Archer, S. 1989. Have Southern Texas savannas been converted to woodlands in recent history? American Naturalist 134;545–561.CrossRefGoogle Scholar
Archer, S., Scifres, C., Bassham, C. R. & Maggio, R. 1988. Autogenic succession in a subtropical savanna: conversion of grassland to thorn woodland. Ecological Monographs 58:111–127.CrossRefGoogle Scholar
Belsky, A. J., Amundson, R. G., Duxbury, J. M., Riha, S. J., Ali, A. R. & Mwonga, S. M. 1989. The effects of trees on their physical, chemical, and biological environments in a semi-arid savanna in Kenya. Journal of Applied Ecology 26:1005–1024.CrossRefGoogle Scholar
Black, C. E. 1967. Methods of soil analysis. American Society of Agronomy Monograph 9. Madison, Wisconsin.Google Scholar
Bucher, E. H. 1982. Chaco and caatinga – South American arid savannas, woodlands and thickets. Pp. 48–59 in Huntley, B. & Walker, B. (eds). Ecology of tropical savannas. Springer-Verlag, Berlin.CrossRefGoogle Scholar
Bucher, E. H. 1987. Herbivory in arid and semi-arid regions of Argentina. Revista Chilena de Historia Natural 60:265–273.Google Scholar
Cherrett, J. M. 1968. The foraging behavior of Atta cephalotes (Hymenoptera, Formicidae). Foraging patterns and plant species attacked in tropical rain forest. Journal of Animal Ecology 37:387–403.CrossRefGoogle Scholar
Cherrett, J. M. 1989. Leaf-cutting ants. Pp. 473–487 in Lieth, H. & Werger, M. J. (eds). Tropical rain forest ecosystems, biogeographical and ecological studies. Ecosystems of the world 14b. Elsevier, New York.CrossRefGoogle Scholar
Connell, J. H. & Slatyer, R. O. 1977. Mechanisms of succession in natural communities and their role in community stability and organization. American Naturalist 111:1119–1144.CrossRefGoogle Scholar
Connor, E. F. & McCoy, E. 1979. The statistics and biology of the species-area relationship. American Naturalist 6:791–833.CrossRefGoogle Scholar
Coutinho, L. M. 1982. Aspectos ecológicos da sauva no cerrado. Os murundus de terra, as caracsteristicas psamofiticas das especies de sua vegetacao e a sua invasao pelo Capim gordura. Revista Brasileira de Biologia 42:147–153.Google Scholar
Emanuel, W. R., Shugart, H. H. & Stevenson, M. 1985. Climate change and the broad-scale distribution of terrestrial ecosystem complexes. Climatic Change 7:457–460.CrossRefGoogle Scholar
Etter, A. & Botero, P. J. 1990. La actividad edáfica de hormigas (Atta laevigata) y su relatión con la dinámica sabana/bosque en los Llanos Orientales de Colombia. Colombia Amazonica 4:77–95.Google Scholar
Fowler, H. G. 1977. Some factors influencing colony spacing and survival in the grass-cutting ant Acromyrmex landolti fracticomis (Forel) (Formicidae; Attini) in Paraguay. Revista de Biologia Tropical 25:88–99.Google Scholar
Fowler, H. G. & Haines, B. L. 1983. Diversidad de especies de hormigas cortadoras de hojas y termitas de túmulo en cuanto a la sucesión vegetal en praderas paraguayas. Pp. 187–201 in Jaisson, P. (ed.). Social insects in the tropics. Université Paris-Nord.Google Scholar
Fowler, H. G., Pereira-Da Silva, V., Forti, C. & Saes, N. B. 1986. Population dynamics of leaf-cutting ants: a brief review. Pp. 123–145 in Logfren, C. S. & Vander Meer, R. K. (eds). Fire ants and leaf-cutting ants: biology and management. Westview Press, Boulder and London.Google Scholar
Glover, P. E., Trump, E. C. & Wateridge, C. 1964. Termitaria and vegetation patterns on the Loita Plains of Kenya. Journal of Ecology 52:367–377.CrossRefGoogle Scholar
Haines, B. 1975. Impact of leaf-cutting ants on vegetation development at Barro Colorado Island. Pp. 99–111 in Golley, F. B. & Medina, E. (eds). Tropical ecological systems. Springer-Verlag, Berlin.CrossRefGoogle Scholar
Haines, B. 1978. Element and energy flows through colonies of the leaf-cutting ant Atta colombica in Pamama. Biotropica 10:270–277.CrossRefGoogle Scholar
Hobbs, R. J. & Mooney, H. A. 1986. Community changes following shrub invasion of grassland. Oecologia 70:508–513.CrossRefGoogle ScholarPubMed
Jackson, M. L. 1964. Soil chemical analysis. Constable, London.Google Scholar
Jonkman, J. C. M. 1976. Biology and ecology of the leaf-cutting ant Atta vollenweideri. Zeitschrift für Angewandte Entomologie 81:140–148.CrossRefGoogle Scholar
Jonkman, J. C. M. 1978. Nests of the leaf-cutting ant Atta vollenweideri as accelerators of succession in pastures. Zeitschrift für Angewandte Entomologie 86:25–34.CrossRefGoogle Scholar
Kellman, M. 1979. Soil enrichment by neotropical savanna trees. Journal of Ecology 67:565–577.CrossRefGoogle Scholar
Lewis, T. G., Pollard, V. & Dibley, C. 1974. Micro-environmental factors affecting diet patterns of foraging in the leaf-cutting ant Atta cephalotes. Journal of Animal Ecology 43:143–152.CrossRefGoogle Scholar
MacArthur, R. H. & Wilson, E. O. 1967. The theory of island biogeography. Princeton University Press.Google Scholar
Madany, M. H. & West, N. E. 1983. Livestock grazing-fire regime interactions within montane forest of Zion National Park, Utah. Ecology 64:661–667.CrossRefGoogle Scholar
Medina, E. & Silva, J. F. 1990. The savannas of northern South America: a steady state regulated by water-fire interactions on a background of low nutrient availability. Journal of Biogeography 17:403–413.CrossRefGoogle Scholar
Neilson, R. P. 1987. Biotic regionalization and climatic controls in western North America. Vegetatio 70:135–147.CrossRefGoogle Scholar
Oliveira-Filho, A. T. 1992. Floodplain ‘murundus’ of Central Brazil: evidence for the termite-origin hypothesis. Journal of Tropical Ecology 8:1–19.CrossRefGoogle Scholar
Ponce, V. T. & Da Cunha, C. N. 1993. Vegetated earthmounds in tropical savannas of central Brazil: a synthesis. Journal of Biogeography 20:219–225.CrossRefGoogle Scholar
Preston, F. W. 1962. The canonical distribution of commonness and rarity. Ecology 43:185–215, 410–432.CrossRefGoogle Scholar
San José, J. J. & Farinas, M. 1983. Changes in tree density and species composition in a protected Trachypogon savanna, Venezuela. Ecology 64:447–435.CrossRefGoogle Scholar
San José, J. J. & Farinas, M. 1991. Temporal changes in the structure of a Trachypogon savanna protected for 25 years. Acta Oecotogica 12:237–247.Google Scholar
San José, J. J., Farinas, M. & Rosales, J. 1991. Spatial patterns of trees and structure factors in a Trachypogon savanna of the Orinoco Llanos. Biotropica 23:114–123.CrossRefGoogle Scholar
Sarmiento, G. 1983. The savannas of tropical America. Pp. 245–288 in Bourliere, F. (ed.). Tropical savannas. Elsevier Scientific Publishing Company, Amsterdam, Netherlands.Google Scholar
Sarmiento, G. 1984. The ecology of Neotropical savannas. Harvard University Press.CrossRefGoogle Scholar
Sarmiento, G. & Monasterio, M. 1975. A critical consideration of the environmental conditions associated with the occurrence of savanna ecosystems in tropical America. Pp. 223–249 in Golley, F. B. & Medina, E. (eds). Tropical ecological systems. Springer-Verlag, Berlin.CrossRefGoogle Scholar
Schofield, C. & Bucher, E. H. 1986. Industrial contributions to desertification in South America. Trends in Ecology and Evolution 1:78–80.CrossRefGoogle ScholarPubMed
Silva, J. F. 1993. Ecologia de poblaciones de plantas de las sabanas del Orinoco. In Herrera, A. & Medina, E. (eds). Ecologia de las Sabanas Neotropicales. Fondo Editorial Acta Cientifica Venezolana, Caracas (en prensa).Google Scholar
Sokal, R. R. & Rohlf, F. 1981. Biometry. W. Freeman, New York, USA.Google Scholar
Troll, C. 1936. ‘Termitensavannen’. Pp. 275–313 in Louis, H. & Panzer, W. (eds). Länderkundliche Forschung Festschrift Norbert Krebs, J. Engelhorns Nachf., Stuttgart.Google Scholar
Vareschi, W. 1960. La Estación Biológica de Los Llanos de la Sociedad Venezolana de Ciencias Naturales y su Tarea. Publication 1, Estación Biológica de los Llanos.Google Scholar
Weber, N. A. 1966. Fungus-growing ants and soil nutrition. Pp. 221–256 in Rapoport, E. (ed.). Progresos en Biologia del Suelo. Actas del Primer Coloquio Latinoamericano. Unesco, Montevideo.Google Scholar