Abstract: This paper investigated species composition of 18 plots in mobile dune, semi-fixed dune and fixed dune, measured 3 kinds of plant functional traits-leaf area (LA), specific leaf area (SLA) and leaf dry matter content (LDMC) from 28 plant species. Then we analyzed the variations of 3 functional traits on the community level, decomposed the species' trait values by adopting the trait-gradient approach (TGA) and studied the correlations between plant functional traits and variations of habitats along the gradient of sand dune fixation. The results show that: (1) community mean leaf area tend to increase with the fixation of sand dune; community mean SLA and LDMC reach the minimum values on the semi-fixed dune. (2) The community niche breadth, calculated by community mean SLA, decreases along the sand dune stabilization gradient, which illustrates that mobile dune and semi-fixed dune plant communities have wider distribution than fixed dune's; (3) The variations of trait values of species are more relative to co-occurring species than the change of mean trait values of plots in which they occur. Following the stabilizing process of sand dune, LA and LDMC have relatively strong positive relationship, and the dependence of theses 2 traits among communities is stronger than that among symbiotic species. Within and among communities, species adopted different strategies to adapt to the change of habitats in the process of sand dune fixation.

Key words: trait-gradient analysis, community mean trait values, Horqin sandy land, leaf area, specific area, leaf dry matter content