Table 1. Average SOC stocks, prediction error, and total predicted SOC stocks for different depth intervals and permafrost regions.
Values in parentheses are the 95% confidence interval of predictions. RMSE, root mean square error.
|
Northern circumpolar permafrost region (17.7 × 106 km2) |
Tibetan permafrost region (1.1 x 106 km2) | |||||||||
| Depth interval (m) |
Sample number |
Average SOC stock (kg m−2) |
RMSE (kg m−2) |
Coefficient of variation (%) |
Total SOC stock (Pg C) |
Sample number |
Average SOC stock (kg m−2) |
RMSE (kg m−2) |
Coefficient of variation (%) |
Total SOC stock (Pg C) |
| 0–0.3 | 2530 | 13 (10–25) | 6.5 | 37 | 232 (183–447) |
173 | 6 (3.5–9) | 3 | 105 | 7 (4–10) |
| 0–1 | 2530 | 29 (24.5–33.5) |
13.5 | 48 | 510 (432–589) |
114 | 8 (6–9.5) | 5.5 | 119 | 9.2 (7–11) |
| 1–2 | 875 | 15 (12–18) | 18 | 86 | 315 (256–377) |
114 | 2 (0.3–5) | 6 | 65 | 2.5 (0.4–6) |
| 2–3 | 538 | 8 (6–10) | 17.5 | 100 | 175 (142–220) |
114 | 2 (1–3.5) | 6 | 42 | 2.7 (1–4.3) |
| Total | 1000 (830–1186) |
14.4 (9–22) | ||||||||