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Instituto Nacional de Pesquisas Espaciais – INPE (2016)

Componentes do ciclo hidrológico e ciclagem de nutrientes na interface atmosfera-planta-solo no semiárido brasileiro

Leal Karinne Reis Deusdará

Titre : Componentes do ciclo hidrológico e ciclagem de nutrientes na interface atmosfera-planta-solo no semiárido brasileiro

Auteur : Leal Karinne Reis Deusdará

Université de soutenance : Instituto Nacional de Pesquisas Espaciais – INPE

Grade : Doutorado em Ciência do Sistema Terrestre 2016

Résumé
This study was conducted in order to characterize and quantify the water and nutrients transfers between the atmosphere, plant and soil compartments considering two environments, one covered with typical vegetation of Caatinga and another covered with pasture. It was also considered the influence of rainfall on these transfers. Water samples were collected to measure the precipitation, throughfall, stemflow, runoff and percolation, during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). Samples were analyzed in order to determine the main inorganic ions (H+, Na+, NH4+, K+, Ca2+, Mg2+, Cl-, NO3-, e SO42-). According to the measurements, interception was 29% and 22%, throughfall was 70% and 76% and stemflow was 1,0% and 1,1% of the incident rainfall during the wet season of 2012 and 2013, respectively. Runoff was lower than 1% of the incident rainfall for both periods and environments and no differences were observed between the pasture runoff and the caatinga covered environment runoff. Percolation was lower at the caatinga covered environment than the pasture environment, although both represented lower than 5% of the incident rainfall. The total ionic rainwater composition suggested a high marine contribution. In the throughfall it was observed the enrichment of Na+ and Cl- and the depletion of Ca2+, Mg2+, SO42- and H+ compared to rainfall. For nitrogenous species no significant differences were observed in throughfall compared to rainfall (except for NH4+ in 2012). For stemflow it was observed the enrichment of most nutrients compared to rainfall, except of SO42- and H+. Although it was observed high concentrations in the stemflow, deposition was low due to its low flow. In this sense, it is possible to infer that changes in land use and occupation can change the productivity of the ecosystem by disrupting the nutrient conservation mechanisms through the canopy. The results are important for the understanding of the precipitation partition by the caatinga canopy, and the influence of this coverage in the soil hydrological components and in the nutrient cycling for this poorly studied area.

Mots Clés  : Caatinga. Effective rainfall. Nitrogen. Atmospheric deposition. Nutrient transfer.

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Page publiée le 25 avril 2019