Floristics, structure and dynamics of plant communities on acid, metal-contaminated soils in the Sudbury area

The present study examines the species composition and structure of the plant communities that occupy the acid, metal-contaminated soils of the Sudbury region, fifteen years after the first such study (Amiro 1979).;Both degraded sites and those that have been revegetated since 1978 were studied. Spatial comparisons were made amongst 68 sites within the damaged area. Forty-six of these sites had been sampled previously (Amiro 1979), before revegetation activities became common.;Species currently present on the acid, metal-contaminated soils of the Sudbury region include those which are relicts of a pre-industrial past, those related to revegetation activities, those with a tolerance for fire, and those that possess adaptations for heavy metal and acid tolerance. Multivariate analyses using cluster analysis, principal component analysis and detrended correspondence analysis have recognized the presence of six community types within the study area. The most significant change in the classification of these communities includes the absence of the Red Maple community that had been recognized by Amiro (1979).;The Birch/Pine community is dominated by white birch and pines. Jack pine and red pine in this community, planted in the early 1980's, have now reached reproductive maturity, and will provide a seed source for the future. The Trembling Aspen community contains many relict individuals and occupies sites where the soil is finely-textured. The Red Oak community seems to be maintaining dominance on the ridge sites it characterized in 1978 (Amiro 1979). At the Big-toothed Aspen dominated sites, this species occurs in the shrub and herb layer, as well as the tree canopy. White birch remains the most common tree species in the Sudbury area. The White Birch community is essentially a monoculture. The Treeless communities contain sites that support populations of Agrostis scabra and Deschampsia caespitosa. (Abstract shortened by UMI.).