INVESTIGADORES
JOBBAGY GAMPEL Esteban Gabriel
artículos
Título:
Two decades of normalized difference vegetation index changes in South America: identifying the imprint of global change
Autor/es:
PARUELO, JM; GARBULSKY, MF; GUERSCHMAN, JP; JOBBAGY, EG
Revista:
INTERNATIONAL JOURNAL OF REMOTE SENSING
Editorial:
Taylor and Francis
Referencias:
Lugar: Abingdon; Año: 2004 vol. 25 p. 2793 - 2806
ISSN:
0143-1161
Resumen:
Estimates of carbon
uptake at the continental scale become urgently needed as the role of countries
as net sinks or sources of carbon gains political and economic importance.
Despite uncertainties related to radiation use efficiency, the amount of
photosynthetically active radiation (PAR) intercepted by the canopy is a
reliable estimator of primary production. Theoretical and empirical data
support the relationship between the Normalized Difference Vegetation Index
(NDVI) derived from the Advanced Very High Resolution Radiometer sensor on National
Oceanic & Atmospheric Administration satellites and the fraction of PAR
intercepted by green canopies. It is shown, for the period
19812000, that there is an overall increase in the radiation intercepted by
the canopy over South America by 1.3%, with rainforests making the largest
absolute contribution (45%), followed by savannas (23%). Under conditions of
minimal agricultural use, disturbance and anthropogenic N deposition, humid
temperate forests showed the highest proportional increase in NDVI during the
last two decades (4.9%). Deserts showed a net reduction in NDVI relative to the
19811985 average (24.4%).
The expansion of agriculture over the last two decades was associated with NDVI
reductions over subtropical forests. NDVI trends in South American region
highlight a biome-dependent imprint of major global change noticeable in only
two decades.