Abstract: Biomass and its allocation, as ecological adaptation strategy of plants, affect plant growth and reproduction. By using large sample method, we analyzed the biomass allocation of ramets of Phragmites australis in two growth stages at different habitats of Zhalong wetland. The results showed that the ramet height, leaf weight, leaf sheath weight, stem weight and ramet weight of P. australis at different habitats were different in the two growth stages, and that the growth of the ramets and modules of P. australis showed great plasticity. The ranges of average proportion of biomass allocation of ramet modules in P. australis were 31.72%-35.29% and between 12.77%-67.51% respectively. There was no significant difference among modules in June (P>0.05), but significant difference among modules in August (P<0.05), with stem being the largest, leaf the second, and leaf sheath the smallest. There was an allometric growth relationship by power function between remat height and ramet weight and the weight of different modules, and also between the weight of different modules and ramet weight. With the increases of ramet weight, the contribution rates of leaves, leaf sheaths and stems were 29.8%-46.6%, 14.9%-31.5% and 20.6%-55.2%, respectively. Our results suggested that the strategies of biomass allocation of ramet in different growth periods and habitats were different, and that there was a stable cooperative growth relationship between the photosynthetic module and the supporting module of the ramet. Moreover， the relative growth between ramet and module was controlled by both genetic and environmental factors.

Key words: Phragmites australis population, ramet, module, biomass, allometry.