CARACTERIZACIÓN FUNCIONAL DE LA VEGETACIÓN DEL URUGUAY MEDIANTE EL USO DE SENSORES REMOTOS

SUMMARY The Normalized Difference Vegetation Index (NDVI) is a spectral index derived from sensors on board of satellites that shows a positive and lineal relationship with the proportion of photosynthetic active radiation absorbed by the canopy. The NDVI is a good estimator of primary productivity, an important ecosystem attribute. In this article the ecosystems of Uruguay were characterized on the basis of three attributes derived of the seasonal curve of the NDVI using 20 years of images of the satellites NOAA/AVHRR (1981-2000). The annual integral of the NDVI (IVN-I), an estimate of the aboveground net primary production; the month of maximal NDVI (IVN-MDM); and the relative range of NDVI (IVN-RREL), attributes that account for the seasonal character of the primary production and reflect critical aspects of the ecosystem functioning, were the calculated attributes. Based on their behavior, each portion of the Uruguayan territory was classified as an ecosystem functional type (TFE), combining supervised and unsupervised classification methods, together with hierarchical analysis. Six TFE that differed significantly among them were identified. The spatial variation of the three attributes was associated mainly to the geomorphologic structure and land use patterns, and not to climatic variables.

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