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, Canada. Recent improvements in air quality enabled conifers to recolonize about 22% of the semi-barrens, an area that consisted of a near monoculture of coppiced and stunted white birch (Betula papyrifera). 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 approximately 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. Increased rates of natural recovery are expected in the future as SO₂ emissions are reduced. Continued municipal and expanded industrial reclamation programs in the 1990s will also greatly reduce the extent of bare land.