Response of Nutrient Release of Periploca sepium Litter to Soil Petroleum Contamination

The alteration of soil biological and chemical properties caused by petroleum contamination might result in limitations in the nutrient release from plant litter and thus threaten the stability of plant communities. In this study, the foliar litter of Periploca sepium was buried into lightly (petroleum concentration was 15 g kg(-1)), moderately (30 g kg(-1)), and seriously (45 g kg(-1)) contaminated soil for a 1 year decomposition experiment. The dynamics of nutrient release and the final nutrient release rates were determined, and the impacts of petroleum contamination on the release of C, N, P, K, Cu, Zn, Fe, Mn, Ca, and Mg from the litter were assessed. The results indicated that the release of all nutrients was significantly accelerated in the slightly and moderately contaminated soil. In contrast, the release of C, N, P, and K was significantly inhibited in the seriously contaminated soil, while only the Cu release from litter was significantly and simultaneously accelerated. Generally, serious soil petroleum contamination would significantly hinder the overall nutrient release from P. sepium litter; thus, P. sepium could only be utilized in the ecological restoration of contaminated soils with a petroleum concentration lower than 45 g kg(-1).