Table 2. Summary of main environmental variables in China and its three regions.
| Main environmental variables | Whole China | EMR | NAR | QTR | ||||
|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
| Mean annual precipitation (mm) | 921.3 | 488.0 | 1029.1 | 448.9 | 253.6 | 136.6 | 483.4 | 249.3 |
| Precipitation of the wettest quarter (mm) | 474.0 | 206.5 | 522.7 | 180.8 | 158.8 | 97.0 | 293.0 | 130.8 |
| Precipitation of the driest quarter (mm) | 60.7 | 58.6 | 70.4 | 59.1 | 9.1 | 7.7 | 11.0 | 9.2 |
| Mean annual dryness | 85.3 | 40.1 | 93.2 | 37.1 | 28.8 | 16.7 | 63.2 | 28.0 |
| Mean annual temperature (0.1 °C) | 123.5 | 61.9 | 140.5 | 49.6 | 54.5 | 32.3 | 10.0 | 35.7 |
| Max temperature of the warmest month (0.1 °C) | 287.6 | 45.4 | 299.5 | 28.1 | 274.9 | 29.8 | 162.8 | 30.4 |
| Min temperature of the coldest month (0.1 °C) | −58.9 | 102.7 | −34.9 | 92.7 | −189.8 | 39.6 | −178.5 | 48.6 |
| Annual potential evapotranspiration (mm) | 1055.8 | 157.4 | 1091.4 | 130.7 | 952.1 | 134.3 | 767.1 | 109.3 |
| Net primary productivity (gC·m−2·a−1) | 437.9 | 231.8 | 488.6 | 208.8 | 129.1 | 79.4 | 225.3 | 195.7 |
| Annual actual evapotranspiration (mm) | 713.1 | 274.8 | 780.5 | 232.3 | 258.8 | 137.8 | 485.9 | 194.9 |
| Normalized difference vegetation index | 494.7 | 135.0 | 527.6 | 98.5 | 303.8 | 163.2 | 346.0 | 167.3 |
| Temperature annual range (0.1 °C) | 346.5 | 86.4 | 334.4 | 83.9 | 464.7 | 31.3 | 341.3 | 38.2 |
| Mean diurnal range (0.1 °C) | 101.5 | 23.7 | 95.4 | 20.0 | 130.5 | 10.6 | 137.6 | 14.8 |
| Temperature seasonality | 8725.3 | 2635.6 | 8522.7 | 2573.9 | 11971.4 | 1243.9 | 7103.1 | 1154.4 |
| Precipitation seasonality | 81.3 | 23.5 | 78.7 | 23.0 | 90.6 | 22.6 | 100.5 | 17.9 |
| Elevational range (m) | 1247.3 | 1086.0 | 1024.8 | 812.1 | 1884.0 | 1533.8 | 3060.8 | 1211.3 |
| Mean elevation (m) | 860.5 | 1100.9 | 541.7 | 609.4 | 1308.9 | 515.4 | 4029.8 | 842.7 |
| Number of land cover types | 6.5 | 2.1 | 6.4 | 2.1 | 6.8 | 2.4 | 7.0 | 2.2 |
EMR: Eastern Monsoon Region, n = 1995; NAR: Northwestern Arid Region, n = 210; QTR: Qinghai-Tibet Plateau Region, n = 171. There are significant differences (one-way ANOVA analysis, p < 0.05) in means of these variables among the three regions.