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Estimativa do stress h??drico da vegeta????o e an??lise de suas condicionantes geoambientais no Vale do Rio dos Sinos: uma aplica????o de sensoriamento remoto

By Luis Ernesto Pertovt

Abstract

A evapotranspira????o compreende trocas h??dricas no sistema solo - planta - atmosfera, as quais ocorrem como resposta ?? demanda evaporativa atmosf??rica. Neste processo, o solo atua como fonte de abastecimento de ??gua, a vegeta????o corresponde ao compartimento intermedi??rio, enquanto a atmosfera ?? o destino final da umidade liberada na forma de vapor. A eventual escassez h??drica do solo reflete-se nos processos ecofisiol??gicos das plantas, cuja resposta ?? o fechamento dos est??matos como forma de evitar o ressecamento e a morte do tecido vegetal. N??o havendo transpira????o foliar, parte da energia absorvida do sol ?? convertida para a forma de calor, elevando-se a temperatura das folhas. Este fen??meno permite detectar o stress h??drico (SH) atrav??s das varia????es de temperatura da vegeta????o (Tv), aqui utilizando-se para isto imagens AVHRR - NOAA (espectro termal) e sua correla????o com a cobertura vegetal (espectro vis??vel e infra-vermelho pr??ximo). Foram gerados um total de 10 mapas regionais de SH nos anos 2003 e 2005, nos quais cinco deles do ano 2005 est??o vinculados e validados com dados de 5 esta????es meteorol??gicas da rede do Centro de Previs??o do Tempo e Estudos Clim??ticos do Instituto Nacional de Pesquisas Espaciais (CPTEC - INPE). Al??m disso se geraram 10 mapas de SH da Bacia Hidrogr??fica do Rio dos Sinos (BHRS), relacionados com dados de precipita????o da Esta????o Meteorol??gica Campo Bom do Instituto Nacional de Meteorologia (INMET). Os resultados mostraram uma disparidade na distribui????o do SH tanto a n??vel regional (Rio Grande do Sul (RS)) como na BHRS, com zonas de stress h??drico permanentemente alto o baixo independente dos valores de precipita????o (PPT), e umbrais de m??ximos e m??nimos SH, o que indicaria a presen??a de condicionantes ambientais naturais na ??rea de estudo.The evapotranspiration includes hydrous interchanges between ground-plant-atmosphere, which is possible as a reply from a evaporative atmospheric demand. In this process, the ground is like a spring of water providing, the vegetation is an intermediate compartment, and the atmosphere is the place where an unit is liberated like vapor. The eventual scarcity of ground water is reflected in plant's physiologic process, which close its stomas to avoid getting dirty and the eventually vegetation tissue decease. Without foliage transpiration, some of the sun ??s energy is absorbed becoming heat, increasing the leaf?? s temperature. This phenomenon allows to detect the hydro stress through change of vegetation ??s temperature using AVHRR-NOAA satellite images (thermal spectrum) and its correlation with the vegetation cover (nearly visible and infrared spectrum). Between 2003 and 2005 10 hydro stress regional maps were made, which five ones were in 2005 and are entailed and validated with dates from five meteorological stations of Weather ??s Foresight Center & Climates Studies of Brazilian Space Investigation National Institute (CPTEC-INPE). Also, from the Hydrographic dos Sinos Basin 10 hydro stress maps were made relating to rain fall dates from Campo Bon Meteorological Station of Meteorology National Institute (INMET). Results show disparity on hydro stress distribution as many on regional level (Rio Grande do Sul (RS)) as on Hydrographic dos Sinos Basin, which permanent high or low levels zones of hydric stress, independent from rain fall values, and minimum and maximum hydro stress threshold, which indicate natural environment conditioning in the study area

Topics: Stress h??drico da vegeta????o, Condicionantes geoambientais, Sensoriamento remoto, Vegetation hydric stress, Geo-environmental conditioners, Remote sensing techniques, ACCNPQ::Ci??ncias Exatas e da Terra::Geologia
Publisher: Universidade do Vale do Rio dos Sinos
Year: 2008
OAI identifier: oai:agregador.ibict.br.BDTD_UNISINOS:oai:www.repositorio.jesuita.org.br:UNISINOS/3037
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