PHOTO INTERPRETIVE STUDY OF RECOVERY OF DAMAGED LANDS NEAR THE METAL SMELTERS OF SUDBURY, CANADA

Aerial photographs from 1970 and 1989 were used to assess the recovery of approximately 100000 ha of smelter-damaged lands near Sudbury, Can ada. Recent improvements in air quality enabled conifers to recolonize about 22% of the ''semi-barrens'', an area that consisted of a near m onoculture of coppiced and stunted white birch (Betula papyifera). The more heavily damaged ''barren'' areas, surrounding the three smelter sites, exhibited very little natural. recovery during the study period . A municipal land reclamation program was responsible for most of the observed revegetation within the barren area. Between 1978 and 1988 a pproximately 2000 ha of barrens were reclaimed through soil treatment, grassing and tree planting. An estimated 7400 ha of the most heavily damaged land is still in need of immediate remedial treatment. Increas ed rates of natural recovery are expected in the future as SO2 emissio ns are reduced. Continued municipal and expanded industrial reclamatio n programs in the 1990s will also greatly reduce the extent of bare la nd.