Title: Survival and ecophysiology of tree seedlings during El Nino drought in a tropical moist forest in Panama
Author: Engelbrecht, Betinna M.J.; Wright, S. Joseph; De Steven, Diane;
Source: Journal of Tropical Ecology, 18: 569-579
Publication Series: Miscellaneous Publication
Description: In tropical forests, severe droughts caused by El Nino events may strongly influence the water relations of tree seedlings and thereby increase their mortality. Data on known-aged seedlings of three common shade-tolerant canopy tree species (Trichilia tuberculata, Tetragastris panamensis and Quararibea asterolepis) in a Panamanian moist forest are presented. Seedling survival during a severe El Nino dry season (1997–98) was compared with prior long-term survival data, and levels of drought stress were assessed by measuring plant water potentials and gas exchange characteristics. Contrary to prediction, dry-season seedling survival was not dramatically reduced in any species compared with that expected in ‘normal’ years. In Trichilia and Quararibea, pre-dawn water potentials averaged -2 MPa and midday water potentials about -3 MPa. Stomatal conductances were very low, averaging 26 mmol m-2 s-1 for Tetragastris and 11–13 mmol m-2 s-1 for Trichilia nd Quararibea. Photosynthetic rates also were very low but consistently positive, averaging 0.8–1.1 mol m-2 s-1. The findings suggest that, once established, seedlings of common tree species in this semi-deciduous forest may be tolerant of drought events.
Keywords: El Nino Southern Oscillation, tropical forest, Panama, Quararibea asterolepis, seedling survival, stomatal conductance, Tetragastris panamensis, Trichilia tuberculata, water relations
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Engelbrecht, Betinna M.J.; Wright, S. Joseph; De Steven, Diane 2002. Survival and ecophysiology of tree seedlings during El Nino drought in a tropical moist forest in Panama. Journal of Tropical Ecology, 18: 569-579
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