5 CONCLUSIONS
Our study focuses on the phytolith and PhytOC contents of different plant communities and their constituent species on a climate gradient in the semi-arid steppe region of the Mongolian Plateau. Our results show that the phytolith and PhytOC contents differ among plant species, and that climatic factors affect phytolith and PhytOC production rates of steppe communities mainly through affecting plant production, whereas their effects on the phytolith and PhytOC contents in plants are relatively small. Our results also demonstrate that plant aboveground biomass (AGB) and PhytOC content are strongly associated with the current-year climate and bioavailable Si content in the soil, while the variation in plant belowground biomass (BGB) and PhytOC content across sites was more correlated with the long-term mean values of climatic and soil factors across the sites, reflecting the perenniality of the belowground part of steppe plants. More studies are warranted to quantify annual PhytOC production from plant belowground part with the effects of plant perenniality incorporated.