Hostname: page-component-77c89778f8-vpsfw Total loading time: 0 Render date: 2024-07-17T15:48:46.209Z Has data issue: false hasContentIssue false
  • English
  • Français

Seed, seedling and sub-canopy survival in monodominant and mixed forests of the Ituri Forest, Africa

Published online by Cambridge University Press:  10 July 2009

Terese B. Hart
Terese B. Hart
Affiliation:
Wildlife Conservation Society, International Programs, 185th St and Southern Blvd, Bronx, N.Y. 10460, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

The central Ituri Forest of Zaïre is characterized by monodominant stands of Gilbert-iodendron dewevrei (mbau forest) within a matrix of mixed forest where Julbernardia seretii is subdominant. Both species produce supra-annual, synchronous (mast) seed crops. The relationship of mast seed production to monodominance for the two tree species was evaluated by investigating: (1) the relationship between seed density and seed survival, (2) the relative impact of mammal versus insect seed predators in high and low seed density areas, and (3) post-germination survival in the understorey. For the latter, tagged seedlings were monitored over 10 years and both species were censused in different understorey size classes. Percentage seed survival was significantly greater for Julbernardia (but not for Gilbertiodendron) in areas of high conspecific seed density. Generalist fruit- and seed-eating mammals were the principal predators on seeds of both species when removed to areas without seed-fall. In mast areas high seed densities appeared to satiate mammalian seed predators but not the specialized beetle seed predators that were the major cause of seed destruction. Gilbertiodendron seedlings survived longer in the forest understorey than did seedlings of Julbernardia. Furthermore, Gilbertiodendron made up a greater proportion of the larger subcanopy size classes in monodominant forest than did Julbernardia in mixed forests. These results suggest that, irrespective of mortality to seeds, the ability to persist in the understorey may confer on Gilbertiodendron a greater probability of reaching and dominating the canopy.

Keywords

Gilbertiodendron dewevreiJulbernardia seretiimonodominant forestpredator satiationseed predationseedling persistence
Type
Research Article
Information
Journal of Tropical Ecology , Volume 11 , Issue 3 , August 1995 , pp. 443 - 459
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

Alexander, I. 1989. Mycorrhizas in tropical forests. Pp. 169–188 in Proctor, J. (ed.). Mineral nutrition in tropical forest and savanna ecosystems. Special Publication No. 9. The British Ecological Society. Blackwell Scientific Publications, Oxford.Google Scholar
Anderson, A. N. 1987. Effects of seed predation by ants on seedling densities at a woodland site in SE Australia. Oikos 48:171–174.CrossRefGoogle Scholar
Augspurger, C. K. 1981. Reproductive synchrony of a tropical shrub: experimental studies on effects of pollinators and seed predators on Hybanthus prunifolius (Violaceae). Ecology 62:755–788.CrossRefGoogle Scholar
Augspurger, C. K. 1984. Seedling survival of tropical tree species: interactions of dispersal distance, light-gaps, and pathogens. Ecology 65:1705–1712.CrossRefGoogle Scholar
Ballardie, R. T. & Whelan, R. J. 1986. Masting, seed dispersal and seed predation in cycad Macrozamia communis. Oecologia 70:100–105.CrossRefGoogle ScholarPubMed
Boucher, D. H. 1981. Seed predation by mammals and forest dominance by Quercus oleoides, a tropical lowland oak. Oecologia 49:409–414.CrossRefGoogle ScholarPubMed
Burgess, P. F. 1969. Preliminary observations on the autecology of Shorea curtisii Dyer ex King in the Malay Peninsula. The Malaysian Forester 32:438.Google Scholar
Chim, L. T. & On, W. F. 1973. Density, recruitment, mortality and growth of dipterocarp seedlings in virgin and logged-over forests in Sabah. The Malaysian Forester 36:3–15.Google Scholar
Clark, D. A. & Clark, D. B. 1984. Spacing dynamics of a tropical rain forest tree: evaluation of the Janzen-Connell model. American Naturalist 124:769–788.CrossRefGoogle Scholar
Connell, J. H. 1971. On the role of natural enemies in preventing competitive exclusion in some marine animals and in rain forest trees. Pp. 298–312 in den Boer, P. J. and Gradwell, G. R. (eds). Dynamics of populations. Centre for Agricultural Publishing and Documentation, Wageningen.Google Scholar
Connell, J. H. & Lowman, M. D. 1989. Low-diversity tropical rain forests: some possible mechanisms for their existence. American Naturalist 134:88–119.CrossRefGoogle Scholar
DeSteven, D. 1982. Seed production and seed mortality in a temperate forest shrub (witch-hazel, Homamelis virginiana). Journal of Ecology 70:437–443.CrossRefGoogle Scholar
Devred, R. 1958. La végétation forestière du Congo Beige et du Ruanda-Urundi. Bulletin de la Société Royale Forestière de Belgique 6:408–468.Google Scholar
Eggeling, W. J. 1974. Observations on the ecology of the Budongo rain forest, Uganda. Journal of Ecology 34:20–87.CrossRefGoogle Scholar
Ernst, W. H. O., Decelle, J. E. & Tolsma, D. J. 1990. Predispersal seed predation in native leguminous shrubs and trees in savannas of southern Botswana. African Journal of Ecology 28:45–54.CrossRefGoogle Scholar
Fassi, B. & Moser, M. 1991. Mycorrhizae in the natural forests of tropical Africa and the Neotropics. Torino 125:157–202.Google Scholar
Gérard, P. 1960. Etude écologique de la forêt dense à Gilbertodendron dewevrei dans la région de I'Uele. INEAC (Institut National pour l'Etude Agronomique du Congo) Série scientifique no. 87, Brussels.Google Scholar
Germain, R. & Evrard, C. 1956. Etude écologique et phytosociologique de la forêt à Brachystegia laurentii. INEAC (Institut National pour l'Etude Agronomique du Congo) Série scientifique no. 67, Brussels.Google Scholar
Harper, J. L. 1977. Population biology of plants. Academic Press, London.Google Scholar
Hart, J. 1986. Comparative dietary ecology of a community of frugivorous forest ungulates in Zaïre. Dissertation. Michigan State University, East Lansing.Google Scholar
Hart, J. & Hart, T. 1990. Status and distribution of antelope in the Ituri Forest. Gnusletter 5:16–18.Google Scholar
Hart, T. 1985. The ecology of a single-species-dominant forest and of a mixed forest in Zaïre, Africa. Dissertation. Michigan State University, East Lansing.Google Scholar
Hart, T. 1990. Monospecific dominance in tropical rain forests. Trends in Ecology and Evolution 5:6–11.CrossRefGoogle ScholarPubMed
Hart, T. B., Hart, J. A. & Murphy, P. G. 1989. Monodominant and species-rich forests of the humid tropics: causes for their co-occurrence. American Naturalist 133:613–633.CrossRefGoogle Scholar
Janzen, D. H. 1971. Seed predation by animals. Annual Review of Ecology and Systemalics 2:465–492.CrossRefGoogle Scholar
Janzen, D. H. 1976. Why bamboos wait so long to flower. Annual Review of Ecology and Systematics 7:347–391.CrossRefGoogle Scholar
Janzen, D. H. 1977. Promising directions of study in tropical animal-plant interactions. Annals of the Missouri Botanical Garden 64:706–736.CrossRefGoogle Scholar
Letouzey, R. 1970. Manuel de botanique forestière: Afrique tropicale, Vol. 2A. Centre Technique Forestier Tropical, Nogent-sur-Marne, France.Google Scholar
Lorimer, C. 1980. Age structure and disturbance history of a southern Appalachian virgin forest. Ecology 61:1169–1184.CrossRefGoogle Scholar
Louis, J. 1947. Contribution à l'étude des forêts équatoriales congolaises. Pp. 902–915 in Comptes Rendus de la Semaine Agricole de Yangambi. INEAC (Institut National pour l'Etude Agronomique du Congo), Brussels.Google Scholar
Meester, J. & Setzer, H. W. 1971. The mammals of Africa. Smithsonian Institution Press, Washington, D.C.Google Scholar
O'dowd, D. J. & Gill, A. M. 1984. Predator satiation and site alteration following fire: mass reproduction of alpine ash (Eucalyptus delegatensis) in southeastern Australia. Ecology 65:1052–1066.CrossRefGoogle Scholar
Rankin, J. M. 1978. The influence of seed predation and plant competition on tree species abundances in two adjacent tropical rain forests. Dissertation. University of Michigan, Ann Arbor.Google Scholar
Silvertown, J. W. 1980. The evolutionary ecology of mast seeding in trees. Biological Journal of the Linnean Society 14:235–250.CrossRefGoogle Scholar
Smith, T. J. III. 1987. Seed predation in relation to tree dominance and distribution in mangrove forests. Ecology 68:266–273.CrossRefGoogle Scholar
Smith, T. J. III, Chan, H. T., McIvor, C. C. & Robblee, M. B. 1989. Comparisons of seed predation in tropical tidal forests from three continents. Ecology 70:146–151.CrossRefGoogle Scholar
Stanley, H. 1980. In Darkest Africa. Charles Scribner's Sons, New York.Google Scholar
Sweeney, B. W. & Vannote, R. L. 1982. Population synchrony in mayflies: a predator satiation hypothesis. Evolution 36:810–821.CrossRefGoogle ScholarPubMed
White, F. 1983. Vegetation map of Africa south of the Sahara (2nd edition). UNESCO/AETFAT/UNSO, Paris.Google Scholar
Wilson, C. G. 1989. Post-dispersal seed predation of an exotic weed, Mimosa pigra L. in the Northern Territory. Australian Journal of Ecology 14:236–240.CrossRefGoogle Scholar