Effects of Si on N and P stoichiometry in degraded grassland of northern China

Abstract

AbstractEcological stoichiometry could provide scientific references for restoring degraded grassland. However, most of the research studies conducted on grasslands emphasise the main biogenic elements and ignore silicon (Si) changes, although Si has been considered to affect the nitrogen (N) and phosphorus (P) accumulation in plants. In this study, we aimed to explore the N, P and Si relationships in plants and soil in grasslands of different degradation statuses of northern China. This study conducted intensive sampling, including samples of eight plant species, the aboveground parts of plant communities and corresponding soil profiles from 69 sites. In addition to the N, P and Si concentrations, multiple soil (e.g., grain size) and vegetation (e.g., coverage) parameters were measured or calculated. Our results showed that the N, P and dissolved Si (DSi) in soil profiles were mainly determined by soil properties, such as the soil water content and pH, whereas plant elemental concentrations were determined by plant families and species. The N concentrations within the same plant species were also significantly influenced by mean annual temperature. Additionally, we used the soil and vegetation parameters to indicate the degradation level and found that grassland degradation could decrease soil elemental concentrations, soil N/P and the N or P concentrations of plant species. The DSi in soil had significantly positive correlation with the plant N and P concentrations (p < 0.05) and showed high independent effect on them. Given the benefits of Si on plants, future management practices relating to grassland restoration should consider the Si cycle.