Soil moisture dominated the temporal dynamics of litter moisture content in subtropical forests: a 7-year observation in south China

•The litter moisture in natural state increased along forest restoration in subtropical China.•Soil moisture in topsoil plays a major role in controlling the litter moisture content.•The litter moisture is more sensitive to changes in environmental conditions as compared to the soil moisture.•The litter moisture can be a useful tool in indicating the change in stand environment.