Spatial pattern of different component carbon in varied grasslands of northern China

•Carbon storage in northern China's grassland was estimated to be 29.9 Pg.•Alpine grassland contributed the highest, while desert grassland was the lowest.•The BGB still had a proportion of 15.8% under the 60 cm layer.•The SOCD in 0-20 cm layer has a large variation among different grasslands.•The total carbon density in China's grasslands was lower than the global level.

As one of the major terrestrial ecosystems, grasslands play a vital role in the global carbon cycle. However, the estimation of carbon stock in China's grasslands still remains controversial. Using the measured data from spatial stratified sampling (including 200 sites; 400 soil profiles, 2400 soil samples in the depth of 0-100 cm, 400 above-ground biomass carbon data, and 2400 below-ground biomass carbon data), together with the EVI (enhanced vegetation index), the estimation of total carbon stock was calculated at 29.9 Pg, with an area of 2.63 × 106 km2 and the storage of SOC was larger than that of biomass carbon regardless of grassland types. The carbon density of grasslands showed a tendency of decreasing from the southeast to the northwest. Alpine grassland contributed the most (74.2%) of the total carbon storage, while the Desert grassland contributed the least (4.3%). The vertical distribution of carbon density varied strongly among different grassland types and a proportion of 15.8% of total carbon still stored at the layer of 60-100 cm. Since this study combined spatial stratified sampling (based on grassland type and community level, sampled belowground samples to a depth of 0-100 cm) with remote sensing data, it is believed that this estimation of the stock and spatial pattern of carbon in grasslands of northern China is more accurate. Therefore, these results will be conducive for understanding the contribution of different grassland types to the global carbon cycle and providing a reference for future measures taken for increasing carbon storage in grasslands.