Many factors have been shown to affect species assemblages of a community,but studies using long-term spatial-temporal community data are still lacking.In this study,we have analysed population abundance data for 14 rodent species over 25 years for 21 sampling sites.We investigated the effects of taxonomic relationships,density dependency,species interaction and climate variation in determining spatial-temporal species assemblages of rodents in arid grasslands of Inner Mongolia of China.By the use of GAMM analysis,we found that intraspecific interactions were more common and more significant than interspecific interactions.Negative interactions between species of the same genus were more common than negative interactions between species of different genera.Dominant species show negative interactions on less abundant or rare species.Positive interactions often occur within rare or less abundant species.By using cluster analysis,we found species assemblages of rodent communities are well explained by assemblages of environmental variables,and species of the same genus do not tend to occur together as compared to species of a different genus of the same family.Our results indicate that arid grassland landscape patterns from eastern grassland to western desert processes,and their underlying resource partitioning and environmental filtering are important force mechanisms in shaping the spatial-temporal community structure and dynamics through effects of intra-or inter-specific interactions and environmental factors.