Red wood ants build their nests as above-ground mounds by collecting organic materials from the forest floor. The effects of ant nest to the soil carbon and nitrogen along with the soil pH, were measured. There was an increase in pH with distance from the nests while there was a decrease in C and N concentration with the distance from the nest increases. The carbon content at the mound and nests center was differ, with carbon percentage more than double at the nests mound than in the center of the nest. In contrast the nitrogen percentage was higher at the nest center but with no significant difference. The pH was increased at the nests center while the soil was more acidic at greater ratio. Red wood ants’ mounds do not significantly alter the C and N concentrations in the forest ecosystem, but they increase spatial heterogeneity of the forest floor by storing organic matter and nutrients.