Carbon storage in terrestrial ecosystems of China: Estimates at different spatial resolutions and their responses to climate change

The carbon storage of terrestrial ecosystems in China was estimated using a common carbon density method for vegetation and soils relating to the vegetation types. Using median density estimates, carbon storage of 35.23 Gt (1 Gt = 10(15) g) in biomass and 119.76 Gt in soils with total of 154.99 Gt were calculated based on the baseline distribution of 37 vegetation types. Total carbon storage of the median estimates at different spatial resolutions was 153.43, 158.08 and 158.54 Gt, respectively, for the fine (10'), median (20') and coarse (30') latitude x longitude grids. There were differences of -1.56, +3.09 and +3.55 Gt carbon storage between baseline vegetation and those at different spatial resolutions. Change in mapping resolution would change area estimates and hence carbon storage estimates. The finer the spatial resolution in mapping vegetation, the closer the carbon storage to the baseline estimation. Carbon storage in vegetation and soils for baseline vegetation is quite similar to that of biomes predicted by BIOME3 for the present climate and CO2 concentration of 340 ppmv. Climate change alone as well as climate change with elevated CO2 concentration will produce an increase in carbon stored by vegetation and soils, especially a larger increase in the soils. Total median carbon storage of terrestrial ecosystems in China will increase by 5.09 Gt and 15.91 Gt for the climate scenario at CO2 concentration of 340 ppmv and 500 ppmv, respectively. This is mainly due to changes in vegetation areas and the effects of changes in climate and CO2 concentration.