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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

  1. Shown correlation coefficients are significant with a p-value < 0.05