Abstract: The study on the age structure of Leymus chinensis population modules in three habitats of Zhalong Nature Reserve showed that at the waxen maturity stage of the population (by the end of July), the tillers were composed of three age classes, with the 1st and 2nd age classes the dominant and the 3rd age class the least, and presented in an increasing age structure. There were 1 080 tillers·m^-2 in inter-forest sand soil, 1 290 tillers·m^-2 in sand soil, and 1 011 tillers·m^-2 in meadow soil. The rhizomes were composed of four age classes, with 8 000 cm·m^-2 of accumulative length in sand soil and 6 948 cm·m^-2 in meadow soil, and presented increasing age structure. The dry matter storage in rhizomes decreased with increasing age. There were four age classes of buds, with the largest number (2 279 buds·m^-2) in meadow soil, the second (2 113 buds·m^-2) in sand soil, and the least (1 410 buds·m^-2) in interforest sand soil. The buds were also of increasing age structure.

Key words: Pirata piraticus, Embryonic development, Temperature, Relative humidity, Photoperiod