Comparison of Forest Carbon Changes in China and the Continental U.S.

Abstract:

Weimin Ju¹, Chunhua Zhang¹, Jing M. Chen², Fangmin Zhang³, Xiqun Wang⁴,

¹International Institute for Earth System Science, Nanjing University, Nanjing, 210023, China

² Department of Geography, University of Toronto, Toronto, Ontario, Canada

³Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China

⁴Planning and Design Institute of Forest Products Industry, State Forestry Administration of China, Beijing, 100010, China

Carbon changes of forests in China and the continental U.S. were investigated using national forest inventory datasets and the InTEC model, which integrates the effects of forest age, atmospheric CO₂concentration, nitrogen deposition, and climate. Pervious to simulations, the changes of net primary productivity (NPP) in the InTEC model was calibrated using field measured NPP and ages of forests.

Both forest inventory and model simulations indicated that carbon sequestration by forests in China increased significantly in recent decades. The forest inventory based estimates indicated that biomass carbon sinks of forest stands were 86.0 Tg C yr^-1 and 174.0 Tg C yr^-1 in China and 132.5 Tg C yr^-1and 147.0 Tg C yr^-1 in the continental U.S. during the periods from 1989 to 2008 and from 1999 to 2008, respectively. The InTEC model simulations indicated that the total carbon sinks of forests were 170.4 Tg C yr^-1, 200.2 Tg C yr^-1, 217.7 Tg C yr^-1 in China and 225.9 Tg C yr^-1, 222.7 Tg C yr^-1, and 230.5 Tg C yr^-1 in the continental U.S. during the periods from 1981 to 2010, from 1991 to 2010, and from 2001 to 2010, respectively. Forest carbon sink density was higher in China than that in the continental U.S., mainly due to a larger fraction of young forests in China. Total carbon sequestration by forests in China was close to that in the continental U.S. during the recent decade.