Introduction: Besides producing food (or fiber) and wood, agroforestry systems may provide a variety of ecosystem services including climate change mitigation. Carbon (C) is stored in both the tree aboveground and belowground biomass, and organic inputs from the trees could increase soil organic carbon (SOC) stocks. However, few studies have assessed the impact of agroforestry systems on carbon storage in soils under temperate climates, as most of them have been performed in tropical regions. Methods: This study was conducted in five silvoarable agroforestry systems and in one silvopastoral system in France. All sites included an agroforestry system and an adjacent agricultural control plot. In all cases, crop and soil management in the agroforestry inter-rows and in the control plot were strictly the same. The ages of the study sites ranged from 6 to 41 years since the tree planting. Sampling depth ranged from 20 to 100 cm and SOC stocks were measured on an equivalent soil mass basis. Tree aboveground biomass was also measured at all sites. Results: In silvoarable systems, the mean SOC accumulation rate was 0.24 (0.09-0.46) Mg C ha-1 yr-1 at 0-30 cm depth. Additional SOC storage was also found in deeper soil layers at the oldest sites (Cardinael et al. 2015). Young plantations also stored SOC but mainly in the tree rows, and we suggested that the herbaceous vegetation growing in the tree rows was a key factor. In the silvopastoral system, additional storage was only found below 40 cm depth. The mean carbon stocks in the aboveground biomass was about 16 (0.02-36.69) Mg C ha-1 for all sites. Additional SOC between the agroforestry and the control plot was related to the age since the tree planting and to soil clay content. Discussion: All together our study demonstrated the potential of agroforestry systems to store SOC in temperate regions. It also pleads for implementation of long-term and diachronic agroforestry trials in order to estimate more accurately SOC stor