The nematode (Scottnema lindsayae) is one of the most common soil invertebrates in the soils of the McMurdo Dry Valleys, Antarctica. A stage-structured population model developed for S. lindsayae was modified to include the effects of anhydrobiosis resulting from soil moisture limitations. Model results indicated that anhydrobiosis lowered temperature requirements needed to establish stable populations by buffering mortality at low temperatures. Moisture conditions producing anyhdrobiosis in about 5% of the population had the lowest temperature requirements; fully active populations required 50% more cumulative annual degree-days to persist. Hence, transfer between active and anhydrobiotic states enhanced the persistence of S. lindsayae in these extreme cold desert soils.