Abstract: This study was conducted in hillside in a typical grassland enclosed for many years in Inner Mongolia,and six transects with 96 sample plots in total were evenly designed along the slope.The purposes of the study were to explore the effects of slope position on species diversity and functional diversity of a typical grassland community,and to discuss the effects of environmental factors and interspecific competition in two different dimensions of diversity.The results showed that: ① The trend of species diversity and functional diversity of the community was consistent with the change of slope position.With the increase of slope position,the species richness and functional richness of the community decreased monotonically; while the species evenness,species dominance,functional evenness and functional dispersion increased at first and then decreased; ② The total phosphorus content on the whole slope was the main factor affecting the species richness of the community and correlated with the functional richness significantly.Interspecific competition was the key factor affecting the species evenness,species dominance,functional dispersion and functional evenness and correlated with the functional evenness significantly; ③ The species diversity and functional diversity of the community were mainly affected by the interspecific competition and environmental factors in the uphill position,but mainly affected by interspecific competition in the downhill position.Therefore,the joint effects of environmental factors and biological factors should be taken into account in exploring the change of community biodiversity pattern.

Key words: slope position, species diversity, functional diversity, interspecific competition, Inner Mongolia