The relative importance of abiotic conditions and subsequent land use on the boreal primary succession of acidogenic mine tailings

Abstract

Many former mine sites have substrates that are very infertile and stressful and must rely on natural primary succession in order to recover a natural plant formation. It is often assumed that these stressful abiotic conditions alone are responsible for the speed of succession, but theory predicts that abiotic stress interacts strongly with levels of anthropic biomass disturbance. We conducted vegetation surveys on a long-term (∼50 years) tailings storage area on a gold mine site, and measured substrate properties (elemental composition, water content, pH), vegetation cover and species composition, as well as levels of human disturbance. Although the substrate was extremely infertile, vegetation cover on these substrates varied from completely denuded areas to forested areas. The main determinant of the amount of vegetation cover was the level of human disturbance, not abiotic conditions. Both abiotic conditions and levels of human disturbance determined the composition of the vegetation. These results highlight the fact that even low levels of human disturbance can have large impacts on the speed of primary succession on these sites.