Dados do Trabalho

Título

The Normalized Difference Vegetation Index in the evaluation of desertified areas in the Brazilian drylands

Resumo

NDVI helps determine areas at higher risk of desertification, enabling targeted environmental recovery measures. The NDVI analysis was conducted in the Desertification Nucleus of Irauçuba/CE, encompassing three sites with two management: grazing exclusion for 21 years (RE), areas undergoing desertification due to overgrazing (DE), and native Caatinga vegetation areas (NV) as controls. Using Landsat 8 satellite imagery from the United States Geological Survey, NDVI calculations were performed on images captured during the rainy and dry seasons with cloud cover below 10%. Bands near-infrared and red were employed for the NDVI calculation, and QGis software was used to generate the NDVI maps. The analysis during the rainy season revealed a higher presence of vegetation, with an index of around 0.5836. NV displayed the highest index of 0.7224, indicating dense vegetation cover. Conversely, DE exhibited a negative NDVI result of -0.0773, while RE had values ranging from 0.5836 to 0.7224. In the dry season, DE and RE demonstrated NDVI values between 0.0767 and 0.2712, respectively, suggesting a diminished presence of vegetation. NV exhibited the highest index of 0.4658, attributed to the dense native Caatinga vegetation. During the dry season, the absence of green coloration in Caatinga's NDVI results from the vegetation's adaptation mechanism to withstand drought. This adaptation leads to the loss of biomass resulting in a grayish appearance characteristic of the Caatinga biome. Consequently, vegetated areas like NV and RE may be misconstrued as devoid of vegetation. The Caatinga's high heterogeneity and the influence of rainfall distribution further complicate the differentiation of ground cover types. Hence, the lack of green coloration in the NDVI during the dry season does not imply the absence of vegetation but rather serves as evidence of the vegetation's adaptive strategy to endure prolonged drought periods

Palavras-chave

Brazilian semiarid, Caatinga, NDVI, Landsat 8, Grazing exclusion.

Instituição financiadora

FUNCAP - Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico

Agradecimentos

FUNCAP e SOHMA - Soil Health & Management Research Group