Abstract: Investigating C, N and P contents and the stoichiometric characteristics of various organs of oak trees under abandoned tailings is of great significance for elucidating biomass production and health status under adverse environment. With a pot experiment, seedlings of Quercus phellos, Quercus rubra, Quercus velutina, Quercus pagoda, Quercus michauxii, Quercus macrocarpa, Quercus virginiana and Quercus fabri were grown in red soil (control) and mine tailings for three years. The biomass and carbon (C), nitrogen (N) and phosphorus (P) contents of leaves, stems, and roots were measured, and the stoichiometric characteristics were analyzed. The results showed that the seedlings of all the eight species could survive in the tailings. The biomass of all species decreased in different degrees compared with the control, with Q. velutina, Q. michauxii and Q. macrocarpa performing well. There was no significant difference in C content in different organs of seedlings in tailing environment compared with the control, but the N and P contents decreased significantly. The N and P contents in roots of Quercus section Lobatae were significantly higher than that of Quercus section Quercus, but different sections did not significantly influence the N and P contents in leaves and stems. The contents of N and P in different organs were leaf > root > stem. The C∶N and C∶P values in different organs of each species in the tailing treatment was significantly higher than that in the control, with higher N and P use efficiency. Moreover, N and P use efficiency in the Quercus section Quercus was higher than that in the Quercus section Lobatae. The N∶P of each species in the control and tailing environment was 6.66-11.74 and 9.96-13.22, respectively. Biomass of seedlings across different species was closely correlated with N and P contents and stoichiometric ratio. N and P contents in each organ were significantly positively correlated each other. Different responses in biomass, C, N and P contents and their stoichiometric ratios in different organs, species and sections were observed under different substrate environments, which resulted in different adaptability of oak trees to mine tailing environment. Oak trees could efficiently obtain nutrient resources, and preferentially allocate N and P to leaves while root system was less affected by tailing. Oak trees could adjust nutrient allocation by improving nutrient use efficiency to adapt to heavy metal environment. The growth of oak trees was co-limited by N and P. Appropriate fertilizer application can improve the tolerance performance of oak in Pb-Zn tailing soil. Q. macrocarpa may be the preferred species for tailing pond management.

Key words: abandoned tailing, Quercus spp., carbon, nitrogen and phosphorus, stoichiometric characteristic