Abstract: Grazing is a major mode of grassland use. Plants are likely to respond positively to grazing disturbance through changes in their functional traits. The researches of plant traits mainly focus on different responses of ecological traits of aboveground functional components, such as stem and leaf, to grazing disturbance. The changes of plant traits reflect the adaptive strategy of maximum resources gain rate, and even are specific manifestation about their own unique survival strategy under grazing pressures. This research method, based on individual ecological characteristics, makes up for some deficiencies of the traditional classification method and is an important tool to study grazing disturbance ecology, and even has the important significance of ecology and evolutionary biology. This paper introduces the definition of plant functional trait and its assembly pattern, summarizes the phenotypic plasticity of plant functional traits, sums up their tradeoff strategy under different grazing intensities, emphasizes the unique value of individual plant functional traits to grassland use, and ultimately puts forward the existing problems and development direction in the future.

Key words: water potential, gas exchange, chlorophyll fluorescence, stomatal limitation, non-stomatal limitation.