Data/hora: 03/06/2024 05:26:13

Provedor de dados: | 61
País: | Brazil
Título: | Seasonal variation in the maximum rate of leaf gas exchange of canopy and understory tree species in an Amazonian semi-deciduous forest
Autores: | Sendall,Kerrie M.; Vourlitis,George L.; Lobo,Francisco A.
Data: | 2009-01-01
Ano: | 2009
Palavras-chave: | Brazil; Brosimum lactescens; Climate change; Ecotone; Photosynthetic response; Tovomita schomburgkii; Tropical transitional forest.
Resumo: | Leaf gas exchange, water potential, and specific leaf area of two tropical semi-deciduous tree species, Brosimum lactescens S. Moore and Tovomita schomburgkii Planch &amp;amp; Triana, were quantified to establish how these properties were affected by seasonal variations in rainfall and leaf canopy position. The study was conducted at a site near Sinop Mato Grosso, Brazil, which is located within the ecotone of savanna and tropical rain forest. Both species exhibited significant declines in leaf water potential (ΨL), specific leaf area, area- and mass-based light saturated photosynthesis and dark respiration, and maximum stomatal conductance during the dry-season, suggesting that leaf structural properties and gas exchange are significantly altered by drought that develops during the 4-month dry season. Internal leaf CO2 concentrations (Ci) were consistently lower during the dry season suggesting that the decline in maximum photosynthesis was due in part to a decline in stomatal conductance. However, seasonal variations in leaf gas exchange were larger for upper-canopy leaves, indicating an important interaction between drought stress and canopy position. The seasonal variation in leaf gas exchange and morphology was presumably due to a combination of drought stress and leaf lifespan. The results of this study suggest that drought has important implications for the leaf physiology and morphology of semi-deciduous Amazonian forest trees.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202009000100008
Editor: | Brazilian Journal of Plant Physiology
Relação: | 10.1590/S1677-04202009000100008
Formato: | text/html
Fonte: | Brazilian Journal of Plant Physiology  v.21 n.1 2009
Fonte: | info:eu-repo/semantics/openAccess