The impact of grazing intensity on the allelopathic effect of Artemisia frigida in a temperate grassland in northern China

Abstract

Allelopathy is an important factor affecting plant community structure. However, few studies have focused on the mechanisms of allelopathy in the process of community succession driven by different grazing intensities. Therefore, field sampling, indoor experiments and field control experiments were conducted in a temperate grassland in northern China. We aimed to detect the impact of different grazing intensities on the chemical components and allelopathic effect of aqueous extracts of Artemisia frigida. The seed germination rate, radicle length, plant height and biomass of the four tested plant species were used to quantify the allelopathic effect of A. frigida. Grazing intensity altered the composition and concentration of chemical components contained in aqueous extracts of A. frigida. The maximum relative contents of 1,8-cineole and β-terpineol both occurred under heavy grazing. The allelopathic effect of A. frigida varied significantly among different grazing intensities and tested species, and the interaction effects between grazing intensity and tested species were also significant. The allelopathic effects of A. frigida significantly influenced the seed germination rate and radicle length of all the test species except Medicago sativa. The aqueous extracts of A. frigida also significantly affected the aboveground, belowground and total biomass of M. sativa and Melilotus officinalis. The allelopathic effect of A. frigida significantly promoted its own plant biomass and inhibited the plant biomass of Stipa krylovii. Our results confirmed that the allelopathic effects of A. frigida partly regulated the process of species composition in degraded rangelands.