Afforestation is providing soil C sequestration of atmospheric CO₂ in both the plant biomass and soil. Tree growth on prairies can also sequester C. Its other effects such as those on the soil profile, microorganisms and nutrient cycling are not well established. The Nebraska National Forest at Halsey was sampled to explore the effects on amounts and distribution of SOM and associated microorganisms under cedars and pines planted on native sandy prairie approximately 75 years ago. Cedars contained the largest amount of soil C attributed to large input of fine roots and litter. Pine stands contained the largest amount of litter C but contained the least amount of total soil C. Results of field d¹³C analysis indicated there was very litter decomposition of prairie C under cedars pines accelerated decomposition. Litter was exchanged between all three sites to determine differences in decomposer communities. Stable isotope probing of FAME samples was used to determine community shifts in d¹³C values which indicated which groups of organisms are utilizing the transplanted litter. Chloroform fumigations measured changes in microbial biomass. The mycorrhizal fatty acids were dominant in the cedar. Our research suggests changes in soil C and nutrient content following land conversion from prairie to forest are dependent on the species planted. Overall, if ecosystems are to be used as sinks for atmospheric C, then we must know the relative impacts of different management strategies on soil C pools and microbial populations to prescribe the best management options.