Table 3 Best models for aboveground biomass components considering all predictors and only dbh, where y is dry biomass (in kilograms per tree), d is dbh (in centimeters), h is tree height (in meters), cl is crown length (in meters), δ is the variance function coefficient, and RSE is the residual standard error

Syria

Needles

\( y={e}^{-2.905+7.582\cdot \frac{d}{d+19.782}+0.581\cdot cl} \)

0.945

0.369

19

Needles

\( y={e}^{-2.302+8.865\cdot \frac{d}{d+20.790}} \)

0.924

0.418

20

Branches

\( y={e}^{-1.794+10.665\cdot \frac{d}{d+21.660}+0.845\cdot \ln cl-0.824\cdot \ln h} \)

0.935

0.372

21

Branches

\( y={e}^{-1.652+10.395\cdot \frac{d}{d+26.816}} \)

0.916

0.455

22

Crown

\( y={e}^{-1.838+8.570\cdot \frac{d}{d+24.443}+0.593\cdot \ln cl} \)

0.943

0.394

23

Crown

\( y={e}^{-1.203+9.925\cdot \frac{d}{d+25.316}} \)

0.917

0.467

24

Stem

y = e ^{− 3.371 + 1.835 ⋅ ln d + 0.937 ⋅ ln h}

0.920

0.153

25

Stem

y = e ^{− 2.698 + 2.440 ⋅ ln d}

0.960

0.239

26

Total

\( y={e}^{-0.849+8.863\cdot \frac{d}{d+15.048}+0.042\cdot h} \)

0.893

0.225

27

Total

y = e ^{− 2.310 + 2.389 ⋅ ln d}

0.882

0.316

28

Lebanon

Needles

\( y={e}^{0.078+10.665\cdot \frac{d}{d+26.492}-0.855\cdot \ln h} \)

0.952

0.442

29

Needles

\( y={e}^{-0.820+8.279\cdot \frac{d}{d+26.854}} \)

0.801

0.752

30

Branches

\( y={e}^{0.625+12.203\cdot \frac{d}{d+30.900}-0.855\cdot \ln h} \)

0.953

0.455

31

Branches

\( y={e}^{-0.253+9.921\cdot \frac{d}{d+33.376}} \)

0.824

0.811

32

Crown

\( y={e}^{1.096+11.737\cdot \frac{d}{d+29.832}-0.855\cdot \ln h} \)

0.953

0.464

33

Crown

\( y={e}^{0.215+9.422\cdot \frac{d}{d+31.814}} \)

0.817

0.889

34

Stem

\( y={e}^{-1.372+8.100\cdot \frac{d}{d+25.960}+0.920\cdot \ln h} \)

0.917

0.185

35

Stem

\( y={e}^{-0.622+10.187\cdot \frac{d}{d+21.196}} \)

0.897

0.367

36

Total

\( y={e}^{0.406+8.991\cdot \frac{d}{d+24.021}+0.030\cdot h} \)

0.737

0.681

37

Total

\( y={e}^{0.474+9.791\cdot \frac{d}{d+25.177}} \)

0.793

0.547

38

Middle East

Needles

\( y={e}^{-0.572+11.470\frac{d}{d+18.745}-1.179\cdot \ln h} \)

0.863

0.593

39

Needles

\( y={e}^{-1.848+8.000\cdot \frac{d}{d+16.803}} \)

0.801

0.909

40

Branches

\( y={e}^{0.113+12.790\cdot \frac{d}{d+23.007}-1.166\cdot \ln h} \)

0.874

0.636

41

Branches

\( y={e}^{-1.149+9.277\cdot \frac{d}{d+22.206}} \)

0.821

0.991

42

Crown

\( y={e}^{0.554+12.372\cdot \frac{d}{d+21.933}-1.168\cdot \ln h} \)

0.870

0.675

43

Crown

\( y={e}^{-0.708+8.866\cdot \frac{d}{d+20.838}} \)

0.815

1.085

44

Stem

\( y={e}^{-1.734+8.090\cdot \frac{d}{d+20.731}+0.886\cdot \ln h} \)

0.861

0.227

45

Stem

y = e ^{− 2.779 + 2.427 ⋅ ln d}

0.959

0.305

46

Total

\( y={e}^{0.119+10.122\cdot \frac{d}{d+23.225}} \)

0.768

0.614

47