Characterization of Biophysical Vegetation - Soil Dynamics along an Eco-climatic Brazilian Transect with Modis Vegetation Indices

Field measurements were conducted on 10 June through 21 July 2002 to collect biophysical data in support of MODIS validation studies. Leaf Area Index (LAI), Plant Area Index (PAI), Absorbed Photosynthetically Active Radiation (fAPAR), biomass, cover components, site characterization and soil characterization were measured. The study areas extended over an eco-climatic transect, from the cerrado in Brasilia National Park through the transition zone in Palmas into the tropical forest near Santarém. We found high relationships between PAI and fAPAR. Furthermore, along the land-cover gradients the biophysical properties as well as soil characteristics significantly varied over the different biome types. The Terra -Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, the normalized different vegetation index (NDVI) and enhanced vegetation index (EVI) products were analyzed for seasonal and spatial patterns of photosynthetic vegetation activity over the same transect. The spatial patterns and relationships of the various landcover types between MODIS VIs and field data during the same period of measurements were investigated, especially in the cerrado biome. This yielded useful insights of the utility of the MODIS VIs.