Seasonal Biophysical Dynamics along an Amazon Eco-climatic Gradient Using Modis Vegetation Indices

We utilized the TerraMODIS Vegetation Index (VI) products to characterize the variability in seasonal and spatial patterns of photosynthetic vegetation activity along an eco-climatic gradient extending from the diverse Brazilian cerrado to the seasonal tropical forest at Tapajos National Forest, including transitional biomes at Santana do Araguaia and land conversion areas. The NDVI and EVI at 500-m and 1-km were used to generate the seasonal profile curves with the aid of quality assurance (QA) parameters for noise removal and data filtering. The seasonal patterns of the cerrado were pronounced with distinct dry and wet seasonal trends. We observed decreasing dry -wet seasonal patterns northward along the transect and in the transitional areas near Santana do Araguaia. However, we observed a reversed seasonal pattern at Tapajos National Forest in which vegetation activity increased during the shorter dry season. This was attributed to the flush of new leaf growth in the dry season and the influence of epiphyll-covered, older leaves in the wetter periods.