Abstract: The reproductive characteristics and resource allocation strategy of plant population are one of the important contents in the plant life history. It is very important to understand and predict the vegetation structure and adaptation strategies in the process of global change. With Saueeurea wellbyi, a common plant distributing in the southern margin of the Qinghai-tibet Plateau, ANOVA was used to analyze the flowering characteristics and resource allocation of 18 populations in 6 altitudes, and the size-dependent relationship between resource input and resource allocation was analyzed by allometric growth model. The results showed that:(1)The size of the individual, the reproductive organs, the biomass of the vegetative organs, tubular loret number, the weight of stamen, the length of anther and the number of pollen were negatively correlated with the altitude. However, tubular loret mass, the weight of pistil, the length of filament and the length of style were positively correlated with the altitude. (2)There was a negative correlation between vegetative allocation and altitude, and reproductive allocation was positively correlated with altitude. (3)There is a trade-off between the number and mass of tubular loret, the weight of pistil and stamen,the length of filament and anther, the length of filament and the number of pollen. (4)There was a significant positive correlation between individual size of S.wellbyi and resource input and resource allocation at different altitudes. The intercepts are significantly different at altitude. Comprehensively, this series of results was the result of long-term evolution and adaptation to the stressful environment of alpine.

Key words: Saussurea wellbyi, Qinghai-tibet Plateau, altitude, resource allocation, allometry