Floristic variation in plant communities on metalliferous mining residues in the northern and southern Pennines, England

Vegetation and soil surveys were conducted on metalliferous mine wastes in the northern and southern Pennines of England. Analyses of vegetation composition in relation to soil chemical variation were performed. Ordination analysis facilitated the detection of groups of co-occurring species which are characteristic of types of metal-contaminated soil. The results of regression analysis implied the importance of soil pH and concentration of available lead or zinc, depending upon region, in determining species distributions. A strong interactive effect was evident between soil phosphorus and zinc content in influencing species distributions in the southern Pennines sample. Regional similarities in the vegetation of apparently similar metalliferous soils existed. The unusually high species richness of some soils was associated with relatively low concentrations of heavy metals. Many species of relatively floristically-rich wastes were also colonists of surrounding grasslands or woodland. This indicated the potential importance of propagule availability and capability for rapid establishment on bare or unstable ground. Mechanisms of physiological stress avoidance, rather than heavy-metai tolerance, may explain the occurrence of non-metallophytes on soils contaminated with lead and zinc.