Effects of a copper smelter on a grassland community in the Puchuncaví Valley, Chile.

A grassland formation has been subjected to pollution generated by the Ventanas copper smelter since 1964 (Puchuncaví Valley, central zone of Chile) with extensive damage to local vegetation and important changes in soil characteristics. The aims of the study were (1) to detect soil parameters that best explain changes observed in plant species richness and abundance and (2) to determine if pollution-derived stresses have also affected regeneration capabilities of plant communities from the soil seed bank. The grassland was quantitatively analysed in terms of physicochemical soil characteristics, plant species diversity and abundance, and soil seed bank species composition and abundance. Results showed that a decrease in total soil nitrogen explained 13% of the changes detected in plant abundance while soil pH and 0.05 M EDTA extractable copper explained 10% and 7%, respectively, of the vegetation change. It was also found that the pollution has already affected plant species regeneration capabilities from the soil seed bank and the microsite distribution of the seeds in soils.