We quantified the effect of a two-year change in climate on the composition, temperature response, and temperature sensitivity of soil microbial communities from California grassland and from a mixed conifer ecosystem. We transplanted soil cores between two temperate ecosystems and incubated them in situ for two years. We found that microbial community composition changed little in this time period. However, there was some indication of increased abundance of thermotolerant organisms in the transplanted conifer soil. Despite minor compositional changes within the community, temperature response and temperature sensitivity of the two microbial communities were affected by the transplant. The conifer soil microbial community appeared to be more affected by the transplant than the grassland soil community. Carbon utilization was temperature-dependent, and was affected by the transplant in conifer soil. Microbial adaptation to antecedent climatic regimes may be an important factor to consider in predicting the impacts of global climate and land use changes on soil quality and carbon cycling.