Table 1.
Current best estimates of (oven-dry) above- and belowground vegetation mass and C pools of vegetation and soils in terrestrial biomes, and of the land C sink, derived from C inventories (Saugier et al. 2001; Grace 2004; Grace et al. 2006).
| biome | area (106 km2) | plant mass (g m−2) | plant Ca (Pg) | soil Cc (Pg) | biome Cd (Pg) | C sinke (Pg yr−1) | |||
|---|---|---|---|---|---|---|---|---|---|
| above | below | above | below | totalb | |||||
| CA | CR | CV | CS | CB | S | ||||
| tropical forest | 17.5 | 30 400 | 8400 | 266 | 74 | 340 | 214 | 553 | 0.66 |
| temperate forest | 10.4 | 21 000 | 5700 | 109 | 30 | 139 | 153 | 292 | 0.35 |
| Boreal forest | 13.7 | 6100 | 2200 | 42 | 15 | 57 | 338 | 395 | 0.47 |
| Mediterranean shrubland | 2.8 | 6000 | 6000 | 8 | 8 | 17 | 71 | 88 | 0.11 |
| tropical savanna and grassland | 27.6 | 4000 | 1700 | 55 | 23 | 79 | 247 | 326 | 0.39 |
| temperate grassland | 15.0 | 250 | 500 | 2 | 4 | 6 | 176 | 182 | 0.22 |
| deserts | 27.7 | 350 | 350 | 5 | 5 | 10 | 159 | 169 | 0.20 |
| tundra | 5.6 | 250 | 400 | 1 | 1 | 2 | 115 | 117 | 0.14 |
| crops | 13.5 | 530 | 80 | 4 | 1 | 4 | 11 | 15 | 0.02 |
| ice | 15.5 | ||||||||
| total | 149.3 | 492 | 160 | 652 | 1485 | 2137 | 2.56 | ||
a
Plant C is assumed to be 50% of dry mass (Saugier et al. 2001).
b
Total plant C (CV)=aboveground C content (CA)+root C content (CR).
c
Soil C is calculated for a depth of 1 m (Saugier et al. 2001).
d
Biome C content (CB)=vegetation C content (CV)+soil C content (CS).
e
C sink (S)=CBa, where a=0.0012 yr−1 (§2 and table 1 of Grace (2004), but corrected to remove errors in that table (cf. table 4 of Grace et al. (2006)).