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Title: Effects of light acclimation and water stress on Amazon tree seedlings of different ecological groups
Other Titles: Efeitos da aclimatação à luz e do stress hídrico em plântulas de árvores amazónicas de diferentes grupos ecológicos
Author: Silva, André Pestana
Advisor: Chaves, Maria Manuela
Keywords: tropical seedlings
light acclimation
plântulas tropicais
aclimatação à luz
Defense Date: 2009
Abstract: Climate change scenarios predict increased drought to some tropical areas, representing a threat to rain-forest biomes. The seedling stage of tropical trees is probably the most sensitive tree life stage to drought. Consequently, differences in seedlings performance to drought may potentially influence biodiversity of the future rain-forest. We studied photosynthesis, stomatal conductance and leaf anatomy in tropical seedlings of Manilkara huberi, Vouacapoua americana and Tachigali paraensis, under natural conditions and water exclusion. Our data suggest that Tachigali was more vulnerable to drought than the other species. Under semi-controlled conditions, the effect of light was studied in three species of Eschweilera and the interaction between light and water availability on seedlings belonging to different ecological groups, the shade-tolerant Vouacapoua americana and the light-demanding Tachigali melinonii. We suggest that Eschweilera coriacea is the less shade-tolerant of the three Eschweilera species studied. Light-demanding species presented a higher plasticity than the shade-tolerant in response to light as far as photosynthesis and stomatal conductance is concerned and lower plasticity in relation to biomass allocation. In Vouacapoua there are independent impacts of shade and drought in photosynthesis, stomatal conductance and sunflecks utilization, contrastingly with Tachigali, where shade mitigates drought effects. Our study suggests that tropical tree seedlings will be differently affected by the increase in drought events and therefore climate change could have an important effect on Amazon rain-forest tree diversity in the future.
Description: Doutoramento em Biologia - Instituto Superior de Agronomia
Appears in Collections:BISA - Teses de Doutoramento / Doctoral Thesis

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