Responses of biomass, nutrient allocation of Leymus chinensis along N, P and water gradients

Three pot experiments, which included two fertilization experiments (N or P fertilizer) with 10 levels of 0，0.5，1，2，4，8，16，32，64,128 gm-2 and a water supply experiment at 11.5，12.7，14.3，16.4，19.1，22.9，28.7，38.2，57.3,114.6 mLcm-2, were conducted to evaluate effects of N or P fertilizer and watering on biomass and nutrient allocation of Leymus chinensis in this study. The results showed that with increase of N and P application, biomass and nutrient contents of both aboveground and underground of L.chinensis tended to increase firstly and then decrease, while rootshoot ratios showed decreasing trends. The responses of biomass and nutrient contents of both aboveground and underground to water gradients were similar as those to the nutrient gradients, but the rootshoot ratios did not show significant change in the water supply experiment. The biomass and nutrient contents of aboveground were higher than those of underground during growth season (in August), whereas there was a contrary trend at the end of growth season (in October). These results indicate that changes in N, P and water availabilities in soil could affect the accumulation of biomass and nutrients both in aboveground and underground of L.chinensis substantially; more biomass and nutrients were allocated to abovegroud in August and then transferred to underground at the end of growth season. Therefore, global climate change changed growth and nutrient use of plant, which will further influence structure and function of the plantsoil system in Inner Mongolia temperate steppes.