Navegando por Autor "DANTAS, Vanessa de Almeida"

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Acesso aberto (Open Access)
Fluxos de calor no dossel vegetativo e infiltração de água no solo, em floresta tropical
(2011-12) DANTAS, Vanessa de Almeida; SILVA, Vicente de Paulo Rodrigues da; COSTA, Antonio Carlos Lôla da; CHAGAS, Glayson Francisco Bezerra das
This study assessed the seasonal and annual variations in both sensible and latent heat storage fluxes in the canopy air-space of tropical rainforest, as well as the infiltration rate in soil in two experimental plots one with exclusion of rainfall and other under actual rainfall. The data used in this study were obtained during the ''Long-term drought impact on water and carbon dioxide fluxes in Amazonian Tropical Rainforest Experiment'' (ESECAFLOR) which is subproject of Large Scale Biosphere Atmosphere Experiment in Amazon forest (LBA), carried out in Caxiuaná National Forest, Pará, Brazil. The air temperature and relative humidity data were collected in a forest profile for each 8 m height layer throughout the 2008 year in order to determine the sensible and latent heat storage fluxes during the rainy season (February, March and April) and less rainy season (September, October and November). The results indicated that sensible heat stored flux in rainforest canopy during the 2008 year was 167.93 W m-2, while the latent heat stored was 5184.38 W m-2. The infiltration rate in the forest was dramatically reduced in the first minutes of the experiment, regardless of soil moisture conditions, and then it presented almost constant behavior throughout the time.
Acesso aberto (Open Access)
Impactos da redução da pluviometria na biomassa aérea da Floresta Amazônica
(2012-01) CHAGAS, Glayson Francisco Bezerra das; SILVA, Vicente de Paulo Rodrigues da; COSTA, Antonio Carlos Lôla da; DANTAS, Vanessa de Almeida
This study was conducted in Caxiuanã National Forest, Pará, Brazil, to analyze the effects of decrease in rainfall on biomass, tree mortality and basal area of tropical rainforest within ESECAFLOR Project (LBA). Two experimental sectors with one hectare each of natural forest were utilized. Plot A was maintained under natural conditions of climate and Plot B with rainfall exclusion of about 90%. The growth parameters presented in this study refer to monthly data during the experimental period from 2005 to 2009 for the two experimental plots. Results showed that a decrease in rainfall affected significantly all tree growth parameters over forest. The main evidence for this is that rainfall exclusion provides a reduction in basal area especially with Diameter at Breast Height more than 10 cm. Also, an increase in both tree mortality rate and consequently loss in plant biomass are larger in forest area with rainfall exclusion than under natural conditions of climate.