Table 2.
Principle components analysis of climate and soil variables across all sites
| Variables | Description | PC1 | PC2 |
|---|---|---|---|
| Climate | |||
| AMT | Annual mean temperature | -0.265 | 0.109 |
| TDR | Mean diurnal range (Mean of monthly (max temp - min temp)) | 0.236 | 0.196 |
| Isoth | Isothermality | 0.017 | 0.485 |
| Tseason | Temperature seasonality (standard deviation ×100) | 0.179 | -0.386 |
| TWM | Max temperature of warmest month | -0.215 | -0.093 |
| TCM | Min temperature of coldest month | -0.262 | 0.197 |
| TAR | Temperature annual range | 0.222 | -0.293 |
| TWEQ | Mean temperature of wettest quarter | -0.231 | -0.180 |
| TDQ | Mean temperature of driest quarter | -0.255 | 0.225 |
| TWQ | Mean temperature of warmest quarter | -0.236 | -0.100 |
| TCQ | Mean temperature of coldest quarter | -0.254 | 0.227 |
| AP | Annual precipitation | -0.265 | -0.125 |
| PWM | Precipitation of wettest month | -0.209 | -0.294 |
| PDM | Precipitation of driest month | -0.253 | -0.034 |
| Pseason | Precipitation seasonality (coefficient of variation) | 0.195 | -0.214 |
| PWeQ | Precipitation of wettest quarter | -0.225 | -0.252 |
| PDQ | Precipitation of driest quarter | -0.252 | -0.027 |
| PWQ | Precipitation of warmest quarter | -0.213 | -0.273 |
| PCQ | Precipitation of coldest quarter | -0.252 | -0.027 |
| Soil | |||
| BULK | Bulk density of the fine earth fraction | 0.366 | -0.363 |
| CEC | Cation exchange capacity of the soil | -0.374 | 0.038 |
| CLAYC | Proportion of clay particles (< 0.002 mm) in the fine earth fraction | -0.383 | -0.182 |
| ORGNC | Organic carbon content | -0.347 | -0.253 |
| pH | Soil pH | 0.392 | 0.047 |
| SANDC | Proportion of sand particles (> 0.05 mm) in the fine earth fraction | 0.398 | -0.160 |
| SILTC | Proportion of silt particles (≥ 0.002 mm and ≤ 0.05 mm) in the fine earth fraction | -0.330 | 0.358 |
| AVWAC | Available water capacity (%) | 0.196 | 0.783 |
The first two PC axes were shown for the 19 climate variables and 8 soil variables