干旱区生态环境知识资源中心

This paper treats long-term changes in area of the "lichen desert),, i.e., the region characterized (especially in the winter period) by average daily SO 2 concentration exceeding 150 mu g/m(3) of air, the maximum allowable concentration (MAC) for populated regions. Comparison of results obtained in 1980/81 and 1991 indicates that the "lichen desert" expanded (from 12 to about 13 km(2)) as a consequence of deterioration of the air quality in the Belgrade area. Comparing the results obtained in 1991 with investigations carried Out in 2007, we found that "lichen desert" shrank substantially in the Belgrade area to a current size of about 11 km(2). The new boundaries of the "lichen desert" are presented, together with the main reasons for its shrinkage in the Belgade area during the last 16 years and predictions of further alterations in the future.