Variabilidade temporal da concentração atmosférica de CO2, fluorescência da clorofila induzida pelo sol e NDVI em áreas com diferentes usos agrícolas no centro-sul do brasil
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Data
2018-08-01
Autores
Morais Filho, Luiz Fernando Favacho
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Universidade Estadual Paulista (Unesp)
Resumo
O Brasil é um país que apresenta grande parte do seu território destinado a atividades agrícolas. Os cultivos de cana-de-açúcar, soja e milho têm grande importância na economia nacional. As práticas de manejo de cultivos e do solo estão intimamente ligadas à emissão de CO2 e a produtividade dos cultivos. Essas práticas também interferem no potencial de fotossíntese, que pode ser medido remotamente por satélites pela fluorescência da clorofila induzida pelo sol (SIF), e pelo Índice de Vegetação pela Diferença Normalizada (NDVI). O monitoramento do CO2 atmosférico via satélite vem sendo amplamente utilizado na compreensão dos fluxos de carbono. Neste estudo investigamos a variabilidade temporal do XCO2, o SIF e o NDVI em áreas com os principais cultivos do centro sul do Brasil, cana-de-açúcar, rotação soja-milho e pastagens. O estudo foi realizado em áreas correspondentes à três usos agrícolas, sendo cana-de-açúcar (Pradópolis – SP), rotação soja-milho (Santo Antônio do Paraíso – PR) e pastagens (Águas Claras – MS). As variáveis analisadas foram Temperatura do ar, Pluviosidade, NDVI, SIF e XCO2. Todos os dados foram ajustados em escalas mensais. A Temperatura do ar foi obtida através da plataforma NASAPOWER, a Pluviosidade através da plataforma NASA GIOVANNI, NDVI via SATveg EMBRAPA e SIF e XCO2 a partir da plataforma OCO-2 da NASA. O período de estudo foi de outubro/2014 a outubro/2016, totalizando uma série temporal de dois anos e todos os dados foram estratificados em escala mensal. Nas séries temporais de NDVI, SIF e XCO2 foram removidas as tendências pelo método da regressão. A SIF variou de 0.141 a 0.6 W m-2 sr-1 μm-1 na cana-de-açúcar, 0.01 a 0.724 W m-2 sr-1 μm-1 em grãos e 0.02 a 2.24 W m-2 sr-1 μm-1 na pastagem. O XCO2 oscilou de 397.9 a 400.5 ppm na cana-de-açúcar, de 396.8 a 404.201 ppm em grãos, e de 400.4 a 407.3 ppm na pastagem. A SIF apresentou correlação linear positiva significativa com o NDVI na cana-de-açúcar e nas pastagens, ao passo que apresentou correlação linear negativa com o XCO2 nas três áreas de estudo. O NDVI e a SIF acompanharam a fenologia dos cultivos nas regiões. O pasto apresentou o maior pico de SIF entre as três áreas de estudo.
Brazil’s territory is covered, mostly, by agricultural activities. Sugarcane, soybean and corn cultivation and livestock plays a major role in the national economy. Management practices in the agricultural activity are correlated to CO2 emission. These practices can affect the crop biomass production and photosynthesis activity. Solar-induced Chlorophyll Fluorescence (SIF) can be used to estimate photosynthesis in cultivation areas. Normalized Difference Vegetation Index (NDVI) has been used to estimate biomass production, soil coverage and crops phenology. Recently, atmospheric CO2 monitored using remote sensing has been widely used in the understanding of carbon fluxes, correlating it to other parameter such as gross and net primary production or even the SIF. The aim of this study was to understand the temporal variability of XCO2, SIF and NDVI in areas under sugarcane cultivation, soybean-corn rotation and grassland to livestock production in the South-Central region of Brazil. This research was conducted in three localities, each one corresponding to one agricultural use: Pradópolis – SP (sugarcane cultivation), Santo Antônio do Paraíso (soybean-corn) and Águas Claras – MS (grassland and pasture to livestock). We analyzed temperature, pluviosity, NDVI, SIF and XCO2. Temperature and pluviosity data were obtained using the NASAPOWER and NASA GIOVANNI platform, respectively. NDVI was obtained in the SATveg project (EMBRAPA). SIF and XCO2 data were obtained in the OCO-2 program. We collected data of a 2-year time series (from October/2014 to October/2016). All these data were transformed to monthly scale. The SIF values of sugarcane varied from 0.141 to 0.6 W m-2 sr-1 µm-1 , from 0.01 to 0.724 W m-2 sr-1 µm-1 in cropland (soybean-corn), and 0.02 a 2.24 W m-2 sr-1 µm-1 in the pasture. The XCO2 varied from 397.9 to 400.5 ppm in the sugarcane cultivation, from 396.8 to 404.201 ppm in the cropland and 400.4 to 407.3 ppm in the pasture. SIF showed a significative positive linear correlation to NDVI in sugarcane and pasture, and a significative negative linear correlation to XCO2 in all áreas. The NDVI and SIF parameters were sensible to the plants phenology.
Brazil’s territory is covered, mostly, by agricultural activities. Sugarcane, soybean and corn cultivation and livestock plays a major role in the national economy. Management practices in the agricultural activity are correlated to CO2 emission. These practices can affect the crop biomass production and photosynthesis activity. Solar-induced Chlorophyll Fluorescence (SIF) can be used to estimate photosynthesis in cultivation areas. Normalized Difference Vegetation Index (NDVI) has been used to estimate biomass production, soil coverage and crops phenology. Recently, atmospheric CO2 monitored using remote sensing has been widely used in the understanding of carbon fluxes, correlating it to other parameter such as gross and net primary production or even the SIF. The aim of this study was to understand the temporal variability of XCO2, SIF and NDVI in areas under sugarcane cultivation, soybean-corn rotation and grassland to livestock production in the South-Central region of Brazil. This research was conducted in three localities, each one corresponding to one agricultural use: Pradópolis – SP (sugarcane cultivation), Santo Antônio do Paraíso (soybean-corn) and Águas Claras – MS (grassland and pasture to livestock). We analyzed temperature, pluviosity, NDVI, SIF and XCO2. Temperature and pluviosity data were obtained using the NASAPOWER and NASA GIOVANNI platform, respectively. NDVI was obtained in the SATveg project (EMBRAPA). SIF and XCO2 data were obtained in the OCO-2 program. We collected data of a 2-year time series (from October/2014 to October/2016). All these data were transformed to monthly scale. The SIF values of sugarcane varied from 0.141 to 0.6 W m-2 sr-1 µm-1 , from 0.01 to 0.724 W m-2 sr-1 µm-1 in cropland (soybean-corn), and 0.02 a 2.24 W m-2 sr-1 µm-1 in the pasture. The XCO2 varied from 397.9 to 400.5 ppm in the sugarcane cultivation, from 396.8 to 404.201 ppm in the cropland and 400.4 to 407.3 ppm in the pasture. SIF showed a significative positive linear correlation to NDVI in sugarcane and pasture, and a significative negative linear correlation to XCO2 in all áreas. The NDVI and SIF parameters were sensible to the plants phenology.
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Palavras-chave
Sensoriamento Remoto, Mudanças Climáticas, Greenhouse Gas, Climate Change