Technical Abstract: We investigated the effects of climate on C fractionation and storage over a 500m elevation transect. The transect parent material, loess, was deposited at the same time, the climate has been stable for the last 3,000 y, and the vegetation is similar. Thus, the variables over the transect are mean maximum temperature ranging from 30 degrees C at the lower slope to 24 degrees C at the upper slope, and precipitation ranging from 180 mm at the lower slope to 270 mm at the upper slope (see graph at left). Soil, sampled under grass and in bare areas, was analyzed for C in the POM (particulate organic matter) fraction and in the fine mineral fraction. In both soil types there was a significant increase in POM-C with elevation, more so in soil associated with grass. The trends for POM-N follow the POM- C with highly significant differences across the transect and between the soil type. The difference in climate from 300 m and 800 m elevation has influenced the C and N content of the soil, both in bare areas and under grass. The increase in plant biomass and decrease in decomposition is the cause of the increase in soil C and N over the transect.