Table 1.

Estimated surface SOC density and stocks (0–20 cm) for global urban greenspaces and major terrestrial biomes

Biome			SOC density (Mg C ha–1) (0-20 cm)	SOC stocks (Pg C) (0–20 cm)	Contribution to global SOC stocks (%)	References
All soilsa			43	543	—	14
Tropical/subtropical forestsa			38	140	25.78
Temperate forestsa			48	144	26.52
Boreal forestsa			93	121	22.28
Grasslands and shrublands a			26	79	14.55
Urban greenspaces			55.2 (51.9–58.6)	1.46 (1.37–1.54)	0.27	This study

Numbers in parentheses indicate 95% confidence intervals in this study. ^a SOC stocks in the 0–20 cm layer is estimated by assuming that this layer contains 73.56% of the SOC stocks in the 0–30 cm layer³¹. ‘All soils’ include SOC stocks of all terrestrial biomes.