Objective It is very important and necessary to establish the national single tree volume biomass model. The research on forest carbon storage change and carbon sequestration capacity has great significance to the forest management policies of estimating regional carbon balance and addressing climate change.
Method With forest resource sampling population and the difference of climate zones, using the survey data from 22 main forest type biomass building models in national forest inventory, establishing regional individual tree regression models of biomass and stock volume, using 11 periods of forest inventory and statistics data from 1949 to 2018, the paper calculates forest carbon storage and carbon sequestration capacity in 70 forest regions to explore forest carbon storage change regulations, causes and contribution to carbon sequestration in 70 years.
Result From 1949 to 2018, forest carbon storage of forest stand and sparse forest increased from 4.509 × 1012 to 8.601 × 1012 kg, increased by 90.74%. Average annual increase was 3.09% during 2014 to 2019; carbon storage of forest storage increased from 4.38 × 1012 to 7.97 × 1012 kg, increased by 81.97%; the lowest carbon intensity of forest stand from 1973 to 1976 was 31.64 t/ha, and increased to 44.30 t/ha from 2014 to 2018, but it cannot reach 46.48 t/ha in 1949. Forest carbon storage in different regions increased differently. Forest carbon storage in north China and southeast coast regions increased by 145.91% and 116.63%, respectively. National and regional forest carbon storage and carbon intensity showed the trends of firstly decreased and secondly increased. The national forest showed the same trends. Before 1981, annual average of carbon accumulation was negative and it was carbon source. After 1981, carbon accumulation was positive. Annual average of biomass carbon sequestration was 0.122 × 1012 kg/year, and carbon accumulation increased gradually. Carbon storage of forest stand accounted for the main parts of forest resource, and its carbon storage was more than 80% of total forest carbon storage. As plantation forest area increased in large proportion and its carbon accumulation increased quickly, annual average biomass carbon sequestration had been 0.04 × 1012 kg/year since 1970s; before 1989, natural forest carbon accumulation was negative, but its carbon sequestration capacity had been increased continually since national forest protection program. It was the main contributor to annual forest carbon accumulation.
Conclusion With national forest protection, ecosystem restoration and protection, and the dominated middle and young age forest stand had entered into quick growing period. The potential of forest carbon sequestration in China will be great.