Afforestation of a trace-element polluted area in SW Spain: woody plant performance and trace element accumulation

Trace element soil pollution can have ecotoxic eVects on plants, which could negatively aVect the restoration of a degraded area. In this work, we studied the revegetation success in diVerent sites within a trace elementpolluted area (Guadiamar River Valley, SW Spain). We analysed the survival and growth patterns of aVorested plants of seven Mediterranean woody species, and their relation to soil pollution, over 3 years. We also analysed the trace element accumulation in the leaves of these species. The area was polluted mainly by As, Cd, Cu, Pb and Zn (soil total concentrations up to 250, 3.6, 236, 385 and 510 mg kg ¡1 , respectively). The woody plant performance was very diVerent between sites and between species; in the riparian sites, plant survival rates were nearly 100%, while in the upland terrace sites species such as Quercus ilex and Ceratonia siliqua showed the lowest survival rates (less than 30%) and also the lowest relative growth rates. There were no signiWcant relationships between plant performance and soil pollution in the riparian sites, while in the upland sites mortality, but not growth, was related to soil pollution, although that could be an indirect eVect of diVerent substrate alteration between sites. The accumulation of soil pollutants in the studied plants was low, with the exception of Salicaceae species, which accumulated Cd and Zn in the leaves above 1 and 200 mg kg ¡1 , respectively. We discuss the results with regard to the aVorestation of trace-element polluted areas.