Abstract -Contamination of the southern taiga forests (Middle Urals) by from cooper smelters (heavy metals combined with SO 2 ) not only decreases the mean rate of decomposition of pure cellulose, but also radically changes the spatial structure of the destruction process. Heterogeneity of distribution of the destruction rate is sharply increased near the source of emission due to differentiation of the space into microsites with high and low destruction rates. The range of spatial heterogeneity amounts to several tens of centimeters and the distribution of microsites with a high rate is random within several tens of meters. A hypothesis has been put forward that the described changes in the spatial structure of the destruction process are related, above all, to disturbed colonization of the substrate by soil microfungi. ECOLOG