Vegetation carbon input moderates the effects of climate change on topsoil organic carbon in China

•Changes in topsoil SOC in China show a significant increasing trends.•The effect of vegetation carbon input on topsoil SOC is more important relative to climatic variables.•Climate change reduced topsoil SOC, while NPP increased topsoil SOC.•The net effect of climate change when vegetation carbon input is considered is an increase in topsoil SOC.