Abstract: The biomass and allocation of modules, as well as their variation of four Asteraceae species including two invasive alien species Bidens pilosa and Conyza canadensis, and two native species Gnaphalium adnatum and Vernonia cinerea at the flowering stage were studied, and the correlation models on plant height and each module of four species under three habitats, and on reproductive and nutritional modules were built to reveal the strategy of reproductive allocation of these species in different habitats, and to determine whether the phenotypic plasticity of invasive species is greater than that of noninvasive ones. The result showed that the biomass of stems of B. pilosa in the nutrientpoor and dry habitat exhibited an increasing tendency, and that of leaves and capitulums decreased. The biomass values of stems, leaves, capitulums, and total biomass of C. canadensis in the nutrientrich and moist habitat were significantly greater than in the other two habitats (P<0.01). The biomass of roots of G. adnatum and V. cinerea in the nutrientpoor and dry habitat had an increasing tendency, and that of stems, capitulums decreased. It is indicated that the invasive plants can regulate their growth and biomass allocation to adapt to the heterogeneous environment. In addition, the coefficients of variation of modules of B. pilosa, C. canadensis, V. cinerea were greater than that of G. adnatum. The correlation of reproductive and nutritional modules of those species displayed a tendency of allometry, indicating that these three species may have a high phenotypic plasticity to enhance the tolerance and adaptability to diverse environments.

Key words: soil fauna, nitrogen, diversity, red soil, intercropping