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Understanding impacts of changed precipitation regimes on plant primary production at species level is critical for predicting ecosystem responses to climate change. We examined the responses of two dominant species of Inner Mongolia grassland to altered seasonal precipitation regimes by a manipulated rainout shelter experiment. With the increase of precipitation amount, the perennial rhizomatous grass Leymus chinensis increased below-ground biomass while the perennial bunchgrass Stipa grandis increased above-ground biomass. With the increase of the interval between rainfall events, biomass production of L chinensis reduced significantly while S. grandis was not affected. Soil moisture and inorganic nitrogen are two dominant environmental factors affecting plant responses in biomass production. Plant functional traits, such as leaf area, leaf number, leaf photosynthetic rate and water use efficiency, also played important roles in affecting species responses to altered precipitation regimes. Our results clearly showed that two species differed significantly in their responses to altered intra-seasonal precipitation regimes, suggesting that the structure and functioning of grassland ecosystem may be significantly altered by specific species responses to future climate change. (C) 2012 Elsevier Masson SAS. All rights reserved.