The age structure of Bromus inermis populations in two habitats in Yili of Xinjiang

In order to evaluate the reproduction potential of natural populations of Bromus inermis in Yili of Xinjiang,the age structure of tillers,rhizomes,winterness tillers and buds of B.inermis sampled from the fields by an unit area sampling method in two habitats(meadow or arid habitat) were analyzed in August 2010.The results showed that in two habitats,the dominance level of tillers,rhizomes,winterness tillers and buds of B.inermis populations at the lowest two age classes was significantly higher than those in other age classes.Reproductive tillers had three age classes,while vegetative tillers,rhizomes,winterness tillers and buds all had four age classes.The tiller nodes of rhizome could reproduce a maximum of four generations and survive for up to five growing seasons.The number of tillers and buds,and the length of rhizomes of populations in the meadow habitat were larger than those in the arid habitat;while the number of winterness tillers was opposite.The ranking of the number of vegetative tillers and winterness tillers were 1-year-old2-year-sold3-year-old4-year-old,the number of buds was 0-year-old1-year-old2-year-old3-year-old.The components of tillers,rhizomes,winterness tillers and buds of B.inermis natural populations showed expansive age structures in toth habitats.