Effects of shell sand burial on seedling emergence, growth and stoichiometry of Periploca sepium Bunge

BACKGROUND: Sand burial plays an irreplaceable and unique role in the growth and distribution of vegetation on the Shell Dike Island in the Yellow River Delta. There are still some unknown on the effects of sand burial on the morphology, biomass, and especially the stoichiometry of Periploca sepium, as well as the relationship between these factors. RESULTS: Shell sand burial depth had a significant influence on seedling emergence, growth, and biomass of P. sepium. Shallow sand burial shortened the emergence time and improved the emergence rate, morphological and biomass of P. sepium compared to deep burial and the control. Burial depth significantly affected the nitrogen (N) and phosphorus (P) contents of the leaves. With deep burial, the carbon/nitrogen (C/N) and carbon/phosphorus (C/P) ratios decreased firstly and then increased with depth, while the nitrogen/phosphorus ratio (N/P) presented the contrary trend. Correlation analysis showed that the stoichiometry of N/P was positively correlated to morphology and biomass of P. sepium at different burial depths. Structural equation model analysis revealed that N was the largest contributor to P. sepium biomass. CONCLUSIONS: Optimal burial depth is beneficial to the seedling emergence, growth and nutritional accumulation of P. sepium. Stoichiometry has an important influence on the morphological formation and biomass accumulation.