Analysis of boreal forest dynamics using the global vegetation index

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Abstract
The objective of this research is to characterize the dynamics of the boreal forest as defined by the period, duration and intensity of photosynthetic activity of the vegetation cover using composite images of the global vegetation index (GVI) derived from NOAA‐AVHRR data. The relationship between GVI data and climatic factors, in particular growing degree‐days and evapotranspiration, is also analyzed. Visible and near infrared AVHRR channels in the global database were corrected for sensor drift and atmospheric effects using the simplified atmospheric correction method (SMAC) developed at LERTS (Rahman and Dedieu, 1994). These corrected data were used to calculate GVI data from April 1985 to December 1991. The results demonstrate the promising potential of GVI data for characterizing the global dynamics of the boreal forest in the regions considered in this study (Eastern Canada, Alaska, Siberia and Finland). Observed variations of vegetation growth parameters of each region can be interpreted in terms of differences between productivity and climate relationship. Corrected GVI data may thus prove to be useful for refining estimates of CO2 fluxes in the boreal latitudes.