Effects of short-term nitrogen and silicon addition on above-ground biomass and biodiversity of alpine meadow of the Qinghai-Tibetan Plateau, China

The nitrogen and phosphate is widely fertilized to meadow, but few silicon is involved. Silicon, a beneficial element, has been proved to encourage plant to grow well by enhancing the resistance to various environmental stresses. A field experiment was carried out to investigate the effects of different levels of nitrogen and silicon addition on above-ground biomass and biodiversity of alpine meadow in the Qinghai-Tibetan Plateau, China. This study indicated that nitrogen fertilizer and silicon fertilizer improved the above-ground biomass of plant community. However, the increase from silicon fertilizer for above-ground plant biomass was far lower than that from nitrogen fertilizer. Nitrogen fertilizer led to declines in species diversity, while silicon fertilizer alleviated the decreasing trend of species diversity. The biological function of silicon fertilizer had an optimal concentration effect at the plant community level. Meanwhile, we hypothesized that silicon fertilizer plays a positive role in maintaining the survival rate of weeds, and the results of this study supported this speculation, in which the proportion of the weed biomass to plant community biomass varied with different silicon fertilizer levels.