Abstract: Iris tenuifolia Pall. is distributed in arid regions as an ornamental flower species. The germination rate of I. tenuifolia seeds in nature is extremely low and the perennating rhizomes play an important role in its propagation. The purpose of this study was to understand the characteristics of phenotypic plasticity and ecological adaptation of I. tenuifolia. Three populations (populations 1, 2 and 3 represented severely dry, dry, and relatively humid habitats, respectively) in Xinjiang, China were chose to investigate the biological characteristics, above and underground biomass of I. tenuifolia. The results showed that the plant’s external morphology was significantly different among the three populations. The total root length and root/shoot ratio were significantly higher in population 1 than in the other two populations, but plant height was higher in population 3. Aboveground biomass of population 3 was significantly higher, but the underground biomass was lower. These findings indicated that, through adjusting the morphology and the allocation ratio of biomass, I. tenuifolia has better phenotypic plasticity to form adaptation strategies in favor of their growth and development at different soil moistures.

Key words: Changbai Mountains, litter decomposition, litter mixing effect, benthic macroinvertebrate., early frost period