INVESTIGADORES
PIÑEIRO Gervasio
congresos y reuniones científicas
Título:
Land-use changes modified ecosystem functioning in west Uruguay
Autor/es:
SARLI, VERÓNICA.; PIÑEIRO, GERVASIO.; PARUELO, JOSÉ M.
Lugar:
Porto Alegre, Brasil
Reunión:
Congreso; Congress of the International Association of Vegetation Science (IAVS); 2002
Institución organizadora:
International Association of Vegetation Science (IAVS)
Resumen:
We characterized ecosystem functioning in northwest Uruguay (Paysandú and Río Negro) using the Normalized Difference Vegetation Index (NDVI), a spectral index linearly related to the fraction of the photosyntetically active radiation (PAR) intercepted by the canopy. We compared the NDVI seasonal dynamics among croplands, implanted forests, native forests and grasslands. For two growing seasons, we derived three attributes from the seasonal NDVI curve: the annual integral (NDVI-I), the annual relative range (the difference between the maximum and minimum NDVI divided by NDVI-I) and the date of the maximum value. We also analyzed the long-term (19 years) effects of afforestation on NDVI-I. NDVI was calculated from AVHRR/NOAA LAC data (spatial resolution1x1km) to compare the seasonal dynamics of the different land cover types and from PAL data (spatial resolution 8x8 km) for the long-term analysis. The seasonal NDVI curves showed significant differences among land covers (p<0.05, n=19). Cultivated forests presented the highest NDVI integral and the lowest relative range. Afforestation increases 9% the intercepted radiation. Increases in PAR interception over the region during the period 1981-2000 were positively associated to the rate of afforestation at the county level (Paysandú: r2= 0,55, n=12, p<0,05; Río Negro: r2= 0,34, n=11, p<0,05).