Vegetation degradation in a permafrost region as seen from space: Noril'sk(1961-1999)

The presence and distribution of airborne and surface contaminants can ofte n be inferred from their effects on vegetation, and this is particularly tr ue in areas of frozen ground where the vegetation is especially vulnerable. In this paper, we take as a study area the region around the city of Noril 'sk in northern Siberia. Non-ferrous metal smelting has been carried out ex tensively in Noril'sk since the 1930s, and it is now one of the world's lar gest producers of nickel. The principal contaminants, which are extensive, are sulphur dioxide and heavy metals. Heat contamination from buildings and industrial activity is also significant in the immediate surroundings of t he city where it has led to degradation of permafrost. We describe two approaches to the use of satellite imagery to monitor veget ation degradation in the Noril'sk region. The first of these compares a pan chromatic spy satellite image from 1961 with a multispectral satellite imag e acquired 34 years later to quantify the gross changes in land cover aroun d Noril'sk. This analysis shows a decrease of approximately 80 km(2) in the vegetated area around the city. The second approach is a regional multitem poral study based on the use of the Normalised Difference Vegetation Index, to which we apply a new correction for phenological variation. This analys is is used to identify a previously unreported area of vegetation decrease to the southwest of Noril'sk. (C) 2001 Elsevier Science B.V. All rights res erved.