We evaluated the impact of litter-fall on soil respiration under a Liquidambar formosana forest and a nearby Cinnamomum camphora forest in Tianjiling National Forestry Park of Changsha, Hunan, using a field study with litter removal and exclusion and litter addition in a full factorial design. Soil respiration was measured using an infrared gas exchange analyzer (LI_COR -6400-09) from January to December 2007. Soil temperature and moisture at 5 cm depth in the experimental plots were also recorded at the same time. On average, soil respiration was significantly decreased by litter exclusion, about 18.6% and 26.5% lower relative to controls in Liquidambar formosana and Cinnamomum camphora forests, respectively. On the other hand, litter addition significantly increased soil respiration by 71.3% and 39.2% in these two forests compared with the controls. Significant relationships were found between soil respiration and soil temperatures at 5 cm soil depth in litter addition and exclusion plots, which could be best described by exponential equations. However, not significant relationships were found between soil respiration and soil moistures at 5 cm depth in all study plots. Soil temperature and moisture together could explain changes in soil respiration of 75.2% and 93.7%, and 90.0% and 92.8% in litter exclusion and addition plots in the Liquidambar formosana and Cinnamomum camphora forests, respectively. The Q10 values were increased in litter exclusion and litter addition plots (3.01, 3.29 and 3.02, 4.37) relative to controls (2.98 and 2.94) in the Liquidambar formosana and Cinnamomum camphora forests, respectively. The results indicated that above-ground litter-fall is an important factor in affecting soil CO2 efflux in forests.