Evaluating the response of a plant community to Zn polluted soil as a basis for the revegetation/remediation of polluted sites

2 páginasFEW studies have assessed the response shown by a plant community to soil poliution in comparison to the number of investigations based on applying recent theoretical knowledge to the ecological restoration of terrestrial ecosystems. This study was designed to contribute to this line of research and to evalúate results ¡n view of possible applications for the revegetation and/or remediation of metal-polluted sites. Based on the fact that Zn is the main metal contaminant of the soil of central Spain, essentially because of previous industrial and mining activities and the presence of -now sealed- mixed urban-industrial waste landfills, we set out to examine the effects of Zn on the process that starts with germination from the existing seed bank and finishes with the development of a plant community. Particular attention was paid to species that were resistant to this type of poliution or had the capacity to accumulate Zn. The procedures used were: (i) recording 66 phytoecological releves as 1 m2plots randomly distributed ¡n oligotrophic pastures on cambisol and distric leptosol soils overlying granite and gneiss; (ii) undertaking a 6-month greenhouse bioassay using soil from the field (mean soil sample from the 66 releves taken in the pastures). This soil was polluted with increasing concentrations of ZnCI2 (300, 500 and 700 ppm) at the start of the experiment. The experimental design mimics one of the most common situations in the real setting: the production of surface leachates by rain falling on soil polluted through industrial or mining activities and on soil comprising the layer used to seal waste landfills; (iii) monitoring the implanting of species in the community and the development of populations by evaluating ecological variables (population density, soil cover, biodiversity); (iiii) determining the Zn contents of plañís able to grow on this soil. Our results, analysed by one-way analysis of variance (ANOVA) and a post-hoc test (LSD), are discussed in terms of: the time needed for a herbaceous community to become implanted in a metal-polluted soil; native species resistant to high Zn concentrations that might be suitable for revegetation measures; and species able to accumulate the metal, as possible candidates for phytoremediation.Peer reviewe