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Survival and growth of juvenile Virola surinamensis in Panama: effects of herbivory and canopy closure

Published online by Cambridge University Press:  10 July 2009

Henry F. Howe
Henry F. Howe
Affiliation:
Department of Biological Sciences, University of Illinois, Box 4348, Chicago, Illinois 60680, USA
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Abstract

Effects of mammalian herbivory and seasonal drought were studied for Virola surinamensis (Myristicaceae) juveniles on Barro Colorado Island, Panama. Seedlings were planted at three months of age and the juveniles were monitored for two years; Treatments included: intact plants protected from mammals by cages, defoliated plants similarly protected, and unprotected plants, each planted in treefall gaps, on gap edges, and in the shaded understorey.

Juveniles planted in treefall gaps survived seasonal drought far better than those planted on gap edges or in shaded understorey. Two years after establishment, juveniles protected from mammalian herbivory showed a 78% survival in gaps (mean 6.8% skylight), 50% survival on gap edges (mean 3.0% skylight), and 33% survival in shaded understorey (1.4% skylight). This advantage was due to accelerated growth in gaps. Juveniles in gaps increased 616% in height, 1075% in leaf number, and 1800% in total leaf area. Comparable numbers in edges were 247%, 378% and 690%; in understorey 33%, 222% and 289%. Accelerated growth in gaps permitted yearlings to survive drought that killed suppressed yearlings in understorey. Mean light differentials as small as 0.6% and 0.3% skylight significantly influenced survival on edges and in shaded understorey, respectively.

Mammalian herbivory killed juveniles directly, and defoliation by mammals strongly accentuated drought mortality by suppressing root development. Natural defoliation was not attributable to gap conditions. Demographic projections from experimental data suggest that mammalian herbivory kills at least 48% of the juveniles of this species over two years, and contributes to the death of 32% more that actually die of drought stress. These projections suggest that 14% of the juveniles of this species die of drought mortality, independent of herbivory, during the first two years. Herbivory most strongly affects plants < 0.5 m in height, and is a continuing source of mortality among suppressed juveniles in the understorey. Steep slopes and large seed size each enhanced juvenile growth and survival in the intermediate conditions of gap edges, but not under the extreme conditions of gaps or shaded understorey.

The context of establishment determines the ‘shade tolerance’ of this conspicuous canopy tree. Without serious mammalian herbivory or extreme dry seasons, V. surinamensis can easily recruit as a shade tolerant plant in the understorey. Under present conditions on Barro Colorado Island, it cannot. Persistence involves both the chances of arrival in different microhabitats, and survival therein. Projections that include both the forest area represented by gaps, gap edges, and understorey and the experimental results from this study indicate that juvenile V. surinamensis can survive for two years in gaps, edges, and understorey, but that the higher proportions of vigorous individuals survive in edges, gaps and understorey, respectively.

Keywords

climate changegap dynamicsherbivoryMyristicaceaePanamaseasonalityseed sizetree recruitmenttropical ecologyVirola surinamensis
Type
Research Article
Information
Journal of Tropical Ecology , Volume 6 , Issue 3 , August 1990 , pp. 259 - 280
Copyright
Copyright © Cambridge University Press 1990

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References

LITERATURE CITED

Anderson, M. C. 1964. Studies of the woodland light climate. 1. The photographic computation of light conditions. Journal of Ecology 52:27–41.CrossRefGoogle Scholar
Augspurger, C. K. 1984a. Seedling survival of tropical tree species: interactions of dispersal distance, light-gaps, and pathogens. Ecology 65:1705–1712.CrossRefGoogle Scholar
Augspurger, C. K. 1984b. Light requirements of neotropical tree seedlings: a comparative study of growth and survival. Journal of Ecology 72:777–795.CrossRefGoogle Scholar
Becker, P. 1983. Effects of insect herbivory and artificial defoliation on survival of Shorea seedlings. Pp. 241–252 in Sutton, S. L., Whitmore, T. C. & Chadwick, A. C. (eds). Tropical rain forest: ecology and management. Blackwell Scientific Publications, London.Google Scholar
Becker, P., Rabenold, P. E., Idol, J. R. & Smith, A. P. 1988. Water potential gradients for gaps and slopes in a Panamanian tropical moist forest's dry season. Journal of Tropical Ecology 4:173–184.CrossRefGoogle Scholar
Brokaw, N. 1982. Treefalls. Frequency, timing, and consequences. Pp. 101–108 in Leigh, E. G., Rand, A. S. & Windsor, D. M. (eds). The ecology of a tropical rain forest: seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington.Google Scholar
Brokaw, N. 1985a. Gap-phase regeneration in a tropical forest. Ecology 66:682–687.CrossRefGoogle Scholar
Brokaw, N. 1985b. Treefalls, regrowth, and community structure in tropical forests. Pp. 53–69 in Pickett, S. T. A. & WhiteP, S. P, S. (eds). The ecology of natural disturbance and patch dynamics. Academic Press, New York.Google Scholar
Brokaw, N. 1987. Gap-phase regeneration of three pioneer tree species in a tropical forest. Journal of Ecology 75:9–19.CrossRefGoogle Scholar
Brokaw, N. & Schiener, S. M. 1989. Species composition in gaps and structure of a tropical forest. Ecology 70:538–541.CrossRefGoogle Scholar
Clark, D. B. & Clark, D. A. 1985. Seedling dynamics of a tropical tree: impacts of herbivory and meristem damage. Ecology 66:1884–1892.CrossRefGoogle Scholar
Croat, T. B. 1978. Flora of Barro Colorado Island. Stanford University Press, Stanford.Google Scholar
De Steven, D. & Putz, F. E. 1984. Impact of mammals on early recruitment of a tropical canopy tree, Dipteryx panamensis, in Panama. Oikos 43:207–216.CrossRefGoogle Scholar
Dietrich, W. E., Windsor, D. M. & Dunn, T. 1982. Geology, climate, and hydrology of Barro Colorado Island. Pp. 21–46 in Leigh, E. G., Rand, A. S. & Windsor, D. M. (eds). The ecology of a tropical forest: seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington.Google Scholar
Fisher, B., Howe, H. F. & Wright, S. J. Juvenile growth of shade-tolerant Virola surinamensis in Panama: Water augmentation in gap nd understorey. Manuscript.Google Scholar
Foster, R. B. 1982. The seasonal rhythm of fruitfall on Barro Colorado Island. Pp. 151–172 in Leigh, E. G., Rand, A. S. & Windsor, D. M. (eds). The ecology of a tropical forest: seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington.Google Scholar
Garwood, N. C. 1983. Seed germination in a seasonal tropical forest in Panama: a community study. Ecological Monographs 53:158–181.CrossRefGoogle Scholar
Howe, H. F. 1983. Annual variation in a neotropical seed dispersal system. Pp. 211–217 in Sutton, S. L., Whitmore, T. C. & Chadwick, A. C. (eds). Tropical rain forest: ecology and management. Blackwell Scientific Publications, Oxford.Google Scholar
Howe, H. F. 1984. Implications of seed dispersal by animals for tropical reserve management. Biological Conservation 30:261–281.CrossRefGoogle Scholar
Howe, H. F. 1986a. Consequences of seed dispersal by birds: a case study from Central America. Journal of the Bombay Natural History Society (Supplement) 83:19–42.Google Scholar
Howe, H. F. 1986b. Seed dispersal by fruit-eating birds and mammals. Pp. 123–189 in Murray, D. R. (ed.). Seed dispersal Academic Press, Sydney.CrossRefGoogle Scholar
Howe, H. F. & Estabrook, G. F. 1977. On intraspecific competition for avian dispersers in tropical trees. American Naturalist 111:817–832.CrossRefGoogle Scholar
Howe, H. F. & Richter, W. 1982. Effects of seed size on seedling size in Virola surinamensis: a within and between tree analysis. Oecologia 53:347–351.CrossRefGoogle ScholarPubMed
Howe, H. F., Schupp, E. W. & Westley, L. C. 1985. Early consequences of seed dispersal for a neo tropical tree (Virola surinamensis). Ecology 66:781–791.CrossRefGoogle Scholar
Howe, H. F. & Vande Kerckhove, G. A. 1980. Nutmeg dispersal by tropical birds. Science 210:925–927.CrossRefGoogle ScholarPubMed
Howe, H. F. & Vande Kerckhove, G. A. 1981. Removal of wild nutmeg (Virola surinamensis) crops by birds. Ecology 62:1093–1106.CrossRefGoogle Scholar
Hubbell, S. P. 1979. Tree dispersion, abundance, and diversity in a tropical dry forest. Science 203:1299–1309.CrossRefGoogle Scholar
Hubbell, S. P. & Foster, R. B. 1983. Diversity of canopy trees in a neotropical forest and implications for conservation. Pp. 25–41 in Sutton, S. L., Whitmore, T. C. & Chadwick, A. C. (eds). Tropical rain forest: ecology and management. Blackwell Scientific Publications, Oxford.Google Scholar
Hubbell, S. P. & Foster, R. B. 1986a. Canopy gaps and the dynamics of a tropical forest. Pp. 77–96 in Crawley, M. J. (ed.). Plant ecology. Blackwell Scientific Publications, Oxford.Google Scholar
Hubbell, S. P. & Foster, R. B. 1986b. Biology, chance, and history and the structure of tropical rain forest tree communities. Pp. 314–329 in Diamond, J. & Case, T. J. (eds). Community ecology. Harper & Row, New York.Google Scholar
Hubbell, S. P. & Foster, R. B. 1987. The spatial context of regeneration in a neotropical forest. Pp. 395–412 in Gray, A. J., Crawley, M. J. & Edwards, P. J. (eds). Colonization, succession and stability. Blackwell Scientific Publications, OxfordGoogle Scholar
Hubbell, S. P. & Foster, R. B. 1989. Short term population dynamics of trees and shrubs in a neotropical forest: El Niño effects and successional change. Manuscript.Google Scholar
Lieberman, D. & Lieberman, M. 1987. Forest tree growth and dynamics at La Selva, Costa Rica (1969–1982). Journal of Tropical Ecology 3:347–358.CrossRefGoogle Scholar
Leigh, E. G.Rand, A. S. & Windsor, D. M. (eds). 1982. The ecology of a tropical forest: seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington.Google Scholar
Marquis, R. J. 1984. Leaf herbivores decrease fitness of a tropical plant. Science 226:537–539.CrossRefGoogle ScholarPubMed
Martinez-Ramos, M., Alvarez-Buylla, E. & Sarukhan, J. 1989. Tree demography and gap dynamics in a tropical rain forest. Ecology 70:555–557.CrossRefGoogle Scholar
Martinez-Ramos, M., Sarukhan, J. & Pinero, D. 1988. The demography of tropical trees in the context of forest gap dyanmics: The case of Astrocarym mexicanum at Los Tuxtlas tropical rain forest. Pp. 293–313 in Davy, A. J., Hutchings, M. J. & Watkinson, A. R. (eds). Plant population biology. Blackwell Scientific Publications, London.Google Scholar
Putz, F. E., Coley, P. D., Lu, K., Montalvo, A. & Aiello, A. 1983. Uprooting and snapping of trees, structural causes and ecological consequences. Canadian Journal of Forest Research 13:1011–1020.CrossRefGoogle Scholar
Rand, A. S. & Rand, W. M. 1982. Variation in rainfall on Barro Colorado Island. Pp. 47–60 in Leigh, E. G., Rand, A. S. & Windsor, D. M. (eds). The ecology of a tropical forest: seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington.Google Scholar
Schupp, E. W. 1988a. Seed and early seedling predation in the forest understory and in treefall gaps. Oikos 51:71–78.CrossRefGoogle Scholar
Schupp, E. W. 1988b. Factors affecting post-dispersal seed survival in a tropical forest. Oecologia 76:525–530.CrossRefGoogle Scholar
Schupp, E. W., Howe, H. F., Augspurger, C. K. & Levey, D. 1989. Arrival and survival in tropical treefall gaps. Ecology 70:562–562.CrossRefGoogle Scholar
Sork, V. 1987. Effects of predation and light on seedling establishment in Gustavia superba. Ecology 68:1341–1350.CrossRefGoogle Scholar
Swaine, M. D., Lieberman, D. & Putz, F. E. 1987. The dynamics of tree populations in tropical forest: a review. Journal of Tropical Ecology (Special Issue) 3(4):359–369.CrossRefGoogle Scholar
Welden, C. W., Hewett, S. W., Hubbell, S. P. & Foster, R. B. 1989. Survival, growth, and recruitment of saplings in canopy gaps and understory shade on Barro Colorado Island, Panama. Manuscript.Google Scholar
Whitmore, T. C. 1988. The influence of tree population dynamics on forest species composition. Pp. 271–292 in Davy, A. J., Hutchings, M. J. & Watkinson, A. R. (eds). Plant population ecology. Blackwell Scientific Publications, Oxford.Google Scholar
Wright, S. J. & Cornejo, F. H. In press. Seasonal drought and the timing of flowering and leaf fall in a neotropical forest. In Bawa, K. (ed.). The reproductive biology of tropical forest plants. Cambridge University Press, Cambridge.Google Scholar