Forest age is a crucial parameter on evaluating carbon sequestration potential of forest ecosystems at regional scale.In this study,a downscaling technique that combined the fifth countrywide forest inventories with satellite-based AVHRR-NDVI data at growing season were used to estimate the spatial patterns of forest age in China and,as a result,the provincial-level statistics of forest age derived from the dominant species were downscaled to a 8-km spatial-explicit dataset.The results indicated that forest ages in China were highly spatially heterogeneous.The southeast regions had the lowest mean forest ages with values ranging from 20 to 30 years; the central regions of Sichuan province and the northwest regions of Xinjiang had the highest forest ages with values higher than 120 years; the other regions of China,such as the southeast regions of Tibet,the northwest regions of Heilongjiang province,the northeast regions of Inner Mongolia,and the southern region of Yunnan province,had the moderate forest ages with values ranging from 70 to 120 years.For the whole China,the forest ages of most of spatial grids ranged from 10 to 80 years that accounted for 85.4% of total forest area,in which 35.3% forests have ages ranged from 20 to 40 years.The probability distribution of ages for all forest in China showed a single peak but non-normal distribution,with a total averaged age of 40.6 years and a standard deviation of 26.6 years.