Vegetation recovery following pollution control at Trail, British Columbia

Sulphur dioxide emissions from the heavy metal smelter at Trail, British Columbia, reached a peak in the late 1920's. By this date serious destruction of the natural vegetation had occurred. The recommendations of a tribunal set up to investigate the problem of air pollution were implemented in 1941. Hence air qualities suitable for the reestablishment of the vegetation have prevailed for some 30 years. Apart from a decrease in precipitation as one moves south through the study area, environmental conditions appear to be of minor importance in controlling recovery patterns with regrowth being limited principally by a shortage of viable propagules. The degree of destruction of the former vegetation cover is considered to be the major factor underlying the patterns of vegetation recovery. Much of the birch and aspen cover appears to have developed initially from remnant rootstocks, with coniferous regrowth restricted to areas where seed is available from mature trees which survived the fumigations.