A 20-year study of NDVI variability over the Northeast Region of Brazil

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dc.contributor.author Barbosa, H en_US
dc.contributor.author Huete, Alfredo en_US
dc.contributor.author Baethgen, W en_US
dc.contributor.editor en_US
dc.date.accessioned 2010-05-28T09:43:52Z
dc.date.available 2010-05-28T09:43:52Z
dc.date.issued 2006 en_US
dc.identifier 2009001125 en_US
dc.identifier.citation Barbosa H, Huete Alfredo, and Baethgen W 2006, 'A 20-year study of NDVI variability over the Northeast Region of Brazil', Academic Press, vol. 67, no. NA, pp. 288-307. en_US
dc.identifier.issn 0140-1963 en_US
dc.identifier.other C1UNSUBMIT en_US
dc.identifier.uri http://hdl.handle.net/10453/8543
dc.description.abstract The natural ecosystems of the Northeast Region of Brazil (NEB) have experienced persistent drought episodes and environmental degradation during the past two decades. In this study, we examined the spatial heterogeneity and temporal dynamics of the NEB using a 20-year time series of Normalized Difference Vegetation Index (NDVI) observations, derived from the National Oceanographic and Atmospheric Administration (NOAA)-Advanced Very High Resolution Radiometer (AVHRR) instrument. A set of 12 000 spatially distributed NDVI values was analysed to investigate significant deviations from the mean-monthly values of the base period (1982?2001) in the study area. Various statistical analyses involving minimum, mean and maximum values, coefficient of variation (CV), standardized anomalies (Z-scores), and 36-month running mean were applied to monthly NDVI values to identify spatial and temporal variations in vegetation dynamics. We found strong seasonal oscillations in the vegetation-growing season (February?May) over the NEB study area, with maximum NDVI observed in April?May and seasonal variations, expressed by the CV, ranging from 14% to 32%. In addition, a consistent upward trend in vegetation greenness occurred over the period 1984?1990, and was strongly reversed in the subsequent period 1991?1998. These upward and downward trends in vegetation greenness followed an inter-annual oscillation of not, vert, similar7?8 years. We also found that dry season peak (September) latitudinal variations in NDVI were 20?25% greater in 1991?1999 than 1982?1990 across the study region. The results of this study suggest that patterns in NEB vegetation variability were a result of the impact of enhanced aridity occurring over the last decade of the 20th century. en_US
dc.language en_US
dc.publisher Academic Press en_US
dc.relation.isbasedon http://dx.doi.org/10.1016/j.jaridenv.2006.02.022 en_US
dc.title A 20-year study of NDVI variability over the Northeast Region of Brazil en_US
dc.parent Journal Of Arid Environments en_US
dc.journal.volume 67 en_US
dc.journal.number 2 en_US
dc.publocation United Kingdom en_US
dc.identifier.startpage 288 en_US
dc.identifier.endpage 307 en_US
dc.cauo.name SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 060200 en_US
dc.personcode 0000058669 en_US
dc.personcode 108636 en_US
dc.personcode 0000058670 en_US
dc.percentage 50 en_US
dc.classification.name Ecology en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US
dc.date.activity en_US
dc.location.activity en_US
dc.description.keywords Vegetation dynamics; Caatinga; El Ni?o; Drought; Degradation en_US


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