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A nested age within stage-structured model was developed to simulate Scottnema lindsayae population dynamics in soils of the McMurdo Dry Valleys, and used to evaluate responses of this species to a range of annual temperature regimes. Simulations predicted that many sites are unlikely to support S. lindsayae, consistent with field observations showing that many soils in the dry valleys lack nematodes. The simulated coefficient of population growth (lambda) varied as a roughly linear function of cumulative annual degree-days (>0degreesC). providing a possible index to site suitability for S. lindsayae that could be used in conjunction with remotely sensed energy data to estimate species distributions. Low temperatures, coupled with long lifespan and slow development of this species, may make dry-valley soil systems sensitive to perturbations that disrupt population dynamics. Indeed, sensitivity analysis indicated that factors affecting adult longevity were the most important determinants of model behavior, further emphasizing the potential impacts of disturbance on local populations.