Abstract: With marking-recapture, hair dyeing, and field observation, this paper studied the social hierarchy and its seasonal changes of Lasiopodomys brandtii in Xilinguole district of Inner Mongolia. The results revealed that in reproductive season, an obvious social hierarchy existed in the family groups of L. bramdtii. The social status from high to low was over-wintering males, over-wintering females, adult newborn females, adult newborn males,and sub-adults and juveniles. Since the newborn males had a lower social status, there was little chance for an adult newborn male to mate within an over-wintering male’s territory. Over-wintering males played a critical role in the population reproduction. By the end of reproductive season, the social status of over-wintering males began to fall down, while that of the newborn males promoted gradually. The present study supported the hypothesis about the polygynous mating system of L. bramdtii.

Key words: Anaerobic degradation, Granular sludge, Pentachlorophenol, Solid-Liquid phase, Slurry