Changes in biomass carbon stocks in China’s forests from 1977 to 2050
Forests play a leading role in alleviating atmospheric CO2elevation and stabilizing the global climate. Located in the eastern margin of Eurasia, China ranks fifth in its forest area and has the largest area of plantation in the world. With the implementation of national afforestation and reforestation programs since the late 1970s, forests in China not only have significantly contributed to the regional and global carbon (C) sinks in the past several decades, but also will be large and persistent C sinks in the future. Detailed assessment of the temporal changes in C sinks/sources of China’s forests is critical to the estimation of the national C budget and can help to constitute sustainable forest management policies for climate change. In this study, we used six periods of the existing national forest inventory data to explore changes in forest biomass C stocks in China between 1977 and 2008. Additionally, we developed a stage-classified matrix models to predict biomass C stocks of China’s forests until 2050 by using data of provincial forest area and biomass C density by the stage class from China’s forest inventories between 1994 and 2008 and the planned forest coverage of the country by 2050.
Total forest biomass C stock increased by 36.3% from 4.72 Pg C (1 Pg = 1015 g) in the early 1980s (1977-1981) to 6.43 Pg C in the late 2000s (2004-2008), with a net accumulation of 1.71 Pg C and an overall biomass C sink rate of 63.3 Tg C a-1. Net C gain was found between two sequential inventory periods, except a slight decrease of 8 Tg C (1 Tg=1012 g) in 1994-1998 probably due to the statistical error on the forest area, and the maximum biomass C sink was found in 2004-2008 with the value of 112.9 Tg C a-1. Furthermore, the predictions showed that total forest biomass C stock will increase from 6.43 Pg C in 2004-2008 to 9.97 Pg C (95% confidence interval: 8.98 ~ 11.07 Pg C) in 2050, with an overall net C gain of 78.8 Tg C yr-1 (56.7~103.3 Tg C yr-1). Our findings suggest that China’s forests have been and will be a large and persistent biomass C sink through 2050.