Plant community productivity is associated with multiple ecological stoichiometry in restoration grasslands

Ecological stoichiometry links the growth of living organisms at the organ level through the strict elemental ratio (carbon [C], nitrogen [N] as well as phosphorus [P]). And this is conducive to maintaining plant productivity in terrestrial ecosystems. Yet, the identification about the significance of multiple ecological stoichiometry (including leaves, roots, soil and microbial biomass) in shaping plant productivity remains unknown. Here, we evaluated the ecological stoichiometry contributions to plant productivity in restoration grasslands on the Loess Plateau (1-, 5-, 10-, 15-, 25-, 30-years restoration grasslands). We found that grassland restoration for 30 years enhanced plant community productivity by 67.34%, which showed the synchronous increase trend with C and N contents in leaves, roots, soil as well as microbial biomass. However, leaves, roots, soil and microbial biomass P contents displayed the opposite change trend with no significant difference in these restoration grasslands (p > 0.05). Microbial biomass C/N/P ratios exhibited thesignificant correlations with leaves, roots, soil C/N/P ratios, as well as plant community productivity (p < 0.01), indicating that stoichiometry of soil microbial biomass is greatly restricted, with the potential to influence plant community productivity. These findings emphasized the crucial role of microbial biomass stoichiometry as a primary regulator on plant community productivity, providing the important data to improve the parameterization of plant growth models in natural grassland of China.