| Table 2. Coefficients of correlation between dendrometric, understory and landscape variables and the significant axes (D) of each principal component analysis (PCA) carried out for six different buffer radii. The highest correlations are shown in bold type.
|
|
|
Variables
|
Buffer 100 m
|
Buffer 200 m
|
Buffer 300 m
|
Buffer 400 m
|
Buffer 500 m
|
Buffer 1000 m
|
|
D1
|
D2
|
D3
|
D4
|
D1
|
D2
|
D3
|
D1
|
D2
|
D3
|
D1
|
D2
|
D3
|
D1
|
D2
|
D3
|
D1
|
D2
|
D3
|
|
Dendrometric
|
Total height
|
0.957
|
–0.079
|
0.059
|
0.086
|
–0.055
|
–0.049
|
0.956
|
–0.135
|
–0.040
|
0.959
|
–0.155
|
–0.050
|
0.958
|
–0.168
|
–0.057
|
0.959
|
–0.075
|
–0.029
|
0.975
|
|
Basal area
|
0.964
|
–0.076
|
0.052
|
0.138
|
–0.108
|
–0.062
|
0.966
|
–0.193
|
–0.047
|
0.956
|
–0.222
|
–0.053
|
0.950
|
–0.248
|
–0.057
|
0.943
|
–0.147
|
–0.039
|
0.979
|
|
Canopy closure
|
0.959
|
–0.170
|
–0.034
|
0.119
|
–0.164
|
–0.116
|
0.962
|
–0.253
|
–0.100
|
0.951
|
–0.275
|
–0.112
|
0.942
|
–0.289
|
–0.117
|
0.938
|
–0.156
|
–0.108
|
0.963
|
|
Understory
|
Total understory cover (%)
|
0.043
|
0.674
|
–0.264
|
0.191
|
–0.324
|
0.695
|
–0.009
|
–0.225
|
0.763
|
–0.010
|
–0.188
|
0.768
|
0.015
|
–0.195
|
0.754
|
0.003
|
–0.171
|
0.601
|
0.018
|
|
Total richness understory
|
–0.170
|
0.893
|
–0.075
|
–0.167
|
–0.031
|
0.877
|
–0.247
|
0.095
|
0.852
|
–0.248
|
0.129
|
0.855
|
–0.246
|
0.146
|
0.857
|
–0.243
|
0.199
|
0.830
|
–0.233
|
|
Shannon understory
|
–0.115
|
0.940
|
0.157
|
–0.001
|
0.161
|
0.923
|
–0.099
|
0.228
|
0.891
|
–0.084
|
0.219
|
0.899
|
–0.088
|
0.209
|
0.906
|
–0.081
|
0.184
|
0.934
|
–0.110
|
|
Understory eveness
|
–0.030
|
0.584
|
0.429
|
0.146
|
0.408
|
0.594
|
0.108
|
0.374
|
0.554
|
0.139
|
0.312
|
0.562
|
0.132
|
0.273
|
0.569
|
0.141
|
0.145
|
0.648
|
0.058
|
|
Landscape
|
Stand area
|
–0.160
|
0.261
|
0.051
|
–0.840
|
0.264
|
0.241
|
–0.295
|
0.345
|
0.182
|
–0.268
|
0.409
|
0.185
|
–0.258
|
0.481
|
0.189
|
–0.216
|
0.278
|
0.265
|
–0.320
|
|
Distance river
|
0.117
|
–0.139
|
–0.511
|
0.401
|
–0.675
|
–0.122
|
0.074
|
–0.783
|
–0.020
|
–0.016
|
–0.803
|
–0.025
|
–0.042
|
–0.818
|
–0.037
|
–0.053
|
–0.869
|
–0.073
|
0.062
|
|
% Total poplar (Surroundings)
|
0.050
|
0.041
|
0.934
|
0.054
|
0.913
|
–0.126
|
–0.133
|
0.898
|
–0.092
|
–0.308
|
0.916
|
–0.009
|
–0.290
|
0.918
|
0.005
|
–0.284
|
0.936
|
–0.070
|
–0.102
|
|
% Adult poplar (Surroundings)
|
–0.033
|
–0.179
|
0.737
|
0.093
|
0.753
|
0.023
|
–0.076
|
0.790
|
0.038
|
–0.162
|
0.837
|
0.014
|
–0.120
|
0.859
|
–0.029
|
–0.142
|
0.873
|
0.066
|
–0.011
|
|
% Young poplar (Surroundings)
|
0.140
|
0.331
|
0.671
|
–0.033
|
0.658
|
–0.220
|
–0.192
|
0.626
|
–0.187
|
–0.328
|
0.656
|
–0.029
|
–0.366
|
0.695
|
0.043
|
–0.357
|
0.699
|
–0.196
|
–0.167
|
|
% Crop
|
0.426
|
0.174
|
–0.524
|
0.626
|
–0.825
|
–0.130
|
0.375
|
–0.882
|
–0.201
|
0.311
|
–0.890
|
–0.219
|
0.285
|
–0.895
|
–0.227
|
0.278
|
–0.867
|
–0.308
|
0.163
|
|
% Urban
|
–0.085
|
0.417
|
0.032
|
–0.300
|
–0.034
|
0.428
|
0.329
|
–0.070
|
0.486
|
0.320
|
–0.092
|
0.444
|
0.360
|
–0.122
|
0.405
|
0.350
|
–0.167
|
0.694
|
0.125
|
|
% Riparian
|
–0.583
|
–0.377
|
0.307
|
0.058
|
0.532
|
–0.055
|
–0.502
|
0.645
|
0.041
|
–0.468
|
0.738
|
–0.044
|
–0.474
|
0.745
|
–0.067
|
–0.488
|
0.766
|
–0.075
|
–0.440
|
|
% Hedgerow
|
0.697
|
0.023
|
–0.029
|
0.220
|
–0.195
|
–0.071
|
0.712
|
–0.426
|
–0.144
|
0.572
|
–0.594
|
–0.114
|
0.508
|
–0.687
|
–0.150
|
0.349
|
–0.628
|
–0.202
|
0.407
|
|
SHDI
|
0.171
|
0.130
|
0.286
|
0.819
|
0.777
|
0.354
|
–0.012
|
0.849
|
0.302
|
–0.163
|
0.847
|
0.282
|
–0.221
|
0.826
|
0.311
|
–0.260
|
0.823
|
0.347
|
–0.125
|