Table 11 The correlation coefficients of variables with the first three principal components (PC1, PC2, PC3) of the PCA analysis of environmental variables
From: Tree regeneration characteristics in limestone forests of the Cat Ba National Park, Vietnam
| Principal components | Variables | Acronym | Correlation coefficient |
|---|---|---|---|
| PC1 | Total site factor | L_TSF | 0.974 |
| Gap fraction | L_GF | 0.960 | |
| Openness | L_OPN | 0.959 | |
| Indirect site factor | L_ISF | 0.922 | |
| Direct site factor | L_DSF | 0.910 | |
| pH | S_pH | − 0.279 | |
| Ellipsoidal leaf area distribution | L_ELAD | − 0.421 | |
| Leaf area index | L_LAI | − 0.794 | |
| PC2 | Cation exchange capacity | S_CEC | 0.852 |
| Rock surface | T_RS | 0.822 | |
| pH | S_pH | 0.785 | |
| Soil moisture | S_SM | 0.733 | |
| Soil humus content | S_SH | 0.727 | |
| Base saturation | S_BS | 0.649 | |
| Slope | T_Sl | 0.596 | |
| Elevation | T_Ele | 0.262 | |
| Clay | S_Clay | 0.245 | |
| Footpaths | H_FP | − 0.214 | |
| Silt | S_Silt | − 0.285 | |
| Hydrolytic acidity | S_HA | − 0.329 | |
| Soil depth | S_SD | − 0.642 | |
| PC3 | Clay | S_Clay | 0.722 |
| Silt | S_Silt | 0.542 | |
| Soil depth | S_SD | 0.482 | |
| Soil moisture | S_SM | 0.439 | |
| Animal traps | H_AT | 0.362 | |
| Cation exchange capacity | S_CEC | 0.280 | |
| Leaf area index | L_LAI | 0.256 | |
| Rock surface | T_RS | − 0.223 | |
| Elevation | T_Ele | − 0.235 | |
| Rock in soil | S_SR | − 0.312 | |
| Slope | T_Sl | − 0.369 | |
| Sand | S_Sand | − 0.837 |