Table 1. Characteristics of study sites and mean values of basic sample trees attributes.
Lp. Site Location Soil types Age [yrs] dbh [mm] h [m] BGB [kg/tree]
1 Dobieszyn1 51°35ʹN, 21°10ʹE Podzols & luvisols 2 0.2 1.03 0.015
2 Dobieszyn1 51°35ʹN, 21°10ʹE Podzols & luvisols 5 7.0 2.20 0.027
3 Dobieszyn1 51°35ʹN, 21°10ʹE Podzols & luvisols 9 28.2 4.97 0.499
4 Dobieszyn1 51°35ʹN, 21°10ʹE Podzols & luvisols 13 58.2 8.61 1.771
5 Dobieszyn2 51°33ʹN, 21°09ʹE Podzols & luvisols 4 0.0 0.64 0.003
6 Dobieszyn2 51°33ʹN, 21°09ʹE Podzols & luvisols 6 13.9 3.26 0.073
7 Dobieszyn2 51°33ʹN, 21°09ʹE Podzols & luvisols 7 29.1 5.15 0.241
8 Dobieszyn2 51°33ʹN, 21°09ʹE Podzols & luvisols 12 64.1 10.24 2.141
9 Kozienice 51°24ʹN, 21°26ʹE Podzols & luvisols 4 0.0 0.73 0.004
10 Kozienice 51°24ʹN, 21°26ʹE Podzols & luvisols 3 20.6 3.10 0.322
11 Kozienice 51°24ʹN, 21°26ʹE Podzols & luvisols 12 36.8 5.95 0.326
12 Kozienice 51°24ʹN, 21°26ʹE Podzols & luvisols 13 56.3 9.33 1.038
13 KPN1 52°21ʹN, 20°43ʹE Luvisols & cambisols 3 0.0 0.44 0.002
14 KPN1 52°21ʹN, 20°43ʹE Luvisols & cambisols 6 16.7 3.64 0.093
15 KPN1 52°21ʹN, 20°43ʹE Luvisols & cambisols 11 35.1 5.75 0.533
16 KPN1 52°21ʹN, 20°43ʹE Luvisols & cambisols 12 60.9 8.30 1.510
17 KPN2 52°20ʹN, 20°41ʹE Luvisols & cambisols 4 1.0 1.37 0.014
18 KPN2 52°19ʹN, 20°40ʹE Luvisols & cambisols 5 16.0 3.08 0.110
19 KPN2 52°19ʹN, 20°39ʹE Luvisols & cambisols 7 25.5 4.98 0.181
20 KPN2 52°19ʹN, 20°39ʹE Luvisols & cambisols 12 46.2 8.28 0.556
dbh – diameter at breast height, h – height, BGB – dry biomass of coarse roots
Table 2. Basic descriptive statistics of coarse roots biomass (BGB) and root-to-shoot (R/S) ratio for analysed young birches growing on post-agricultural lands in central Poland (n = 181).
  min m me max sd cv
BGB [kg/tree] 0.0007 0.4226 0.1234 4.3055 0.7829 185
R/S 0.091 0.245 0.193 1.015 0.154 63
min – minimum, m – mean, me – median, max – maximum, sd – standard deviation, cv – coefficient of variation [%].
1

Fig. 1. Relationship between coarse root biomass and dbh (A), height (B) and age (C) of a tree in young successional silver birch stands on post-agricultural lands in central Poland

Table 3. Goodness-of-fit measures for analysed allometric equations.
Eq. R2 RMSE MSE m PEall sd PEall cv PEall m PEnd0 sd PEnd0 cv PEnd0
1 0.943 0.188 0.002 202 546 270 31 267 854
2 0.943 0.189 0.016 –40 50 123 –22 43 191
3 0.849 0.308 0.039 –39 56 141 –23 54 231
4 0.938 0.197 0.024 –44 49 113 –27 44 164
5 0.939 0.195 0.002 321 833 259 54 406 751
6 0.929 0.211 0.002 390 997 256 68 486 715
7 0.943 0.189 0.011 4 52 1201 –6 35 558
8 0.943 0.188 0.001 108 247 229 23 109 466
Eq. – number of analysed equation, R2 – coefficient of determination, RMSE – root mean square error, MSE – mean square error, PEall – whole range of dbh included in percent error calculation, PEnd0 – only trees with dbh > 0 included in percent error calculation; m – mean, sd – standard deviation, cv – coefficient of variation [%].
2

Fig. 2. Relationship between R/S ratio values and dbh (A), height (B) and age (C) of a tree in young successional silver birch stands on post-agricultural lands in central Poland.