On the western edge of the city of Sudbury, Ontario, exists the largest sulphide tailings compound in
Canada. This compound, which is operated by Inca Ltd., has a total area of 5,500 acres (2,225 ha) and began operation in the 1930s. Oxidation of the 5-10% of residual sulphide originally present in the tailings, combined with trace amounts of nickel and copper, make the tailings acid-generating and phytotoxic. Since the mid-1940s, attempts have been made to revegetate the tailings, the main goal being to stabilize the surface and prevent wind erosion. Today, most of the inactive tailings surfaces have been revegetated to some degree, with the older sites showing a relatively well established tree cover. The oldest of the revegetated sections in this complex is the so-called CD area, on which a vegetation cover has been established for up to thirty years.
The CD area is dominated by stands of white birch (Betula papyrifera), trembling aspen (Populus
tremuloides), red pine (Pinus resinosa), and jack pine (Pinus banksiana). The deciduous species have invaded the area from the hilltops which protrude from the tailings surface, while the conifers were planted from the mid-1970s on. The other main plant assemblage on the CD area is herbaceous, predominantly of grasses and legumes, and is referred to here as the field community. This community has essentially developed from the grass-legume seeding carried out in the late 1950's. The present study examines the edaphic and vegetative properties of representative samples of the three main communities of the CD area - the field community, the jack pine community, and the white birch community.