Vegetation indices variability in the Pampa grasslands in Brazil and Uruguay

Resumo

The Pampa Biome is one of the largest and richest grasslands in the world, with a vast diversity of species and an unique coexistence of several C3 and C4 plants in time and space. The object of this study was to characterize the annual and seasonal variability of NDVI and EVI vegetation indices over grassland types and to identify the possible difference between ecological regions. The study area focuses on 13 ecological regions into the Pampa Biome in Brazil (Rio Grande do Sul State), and Uruguay. The temporal and spatial variability of the vegetation vigor was analyzed through NDVI and EVI vegetation indices for a period from 2000 to 2011. The results showed that NDVI and EVI temporal average patterns are similar and reflect, for each region, the vegetation vigor associated to the soil type, and the rainfall. For both vegetation indices, the high values occur during summer and lower values in winter. However, the intra-annual variability of the vegetation indices are higher during summer, when EVI shows more potential to detect changes in vegetation vigor.